Solar GreenhousesBarbara Bellows, updated by K. Adam NCAT Agriculture Specialists Published 2008© NCAT IP142

Abstract

This resource list discusses basic principles of solar greenhouse design, as

well as different construction material options. Books, articles and Web

sites, and computer software relevant to solar greenhouse design are all

provided in a resource list.

Table of Contents

• Introduction

• Basic Principles of Solar Greenhouse Design

• Solar Greenhouse Designs

• Solar Heat Absorption

• Solar Heat Storage

• Insulation

• Ventilation

• Putting It All Together

• References

• Resources

○ Books

○ Articles, Fact Sheets, and Web Sites

○ Computer Software

Introduction

Since 2000, U.S. greenhouse growers have increasingly adopted high tunnels as the preferred solar

greenhouse technology. Rigid frames and glazing are still common in parts of Europe, and in the

climate-controlled operations in Mexico and the Caribbean that produce acres of winter crops for North

American markets. (For more on climate-controlled technology, see Linda Calvin and Roberta Cook.

Kansas City Center for Urban Agriculture.Photo: NCAT

2005. "Greenhouse tomatoes change the dynamics of the North American fresh tomato industry."

AmberWaves. April. Vol. 3, No. 2.).

All greenhouses collect solar energy. Solar greenhouses are designed not only to collect solar energy

during sunny days but also to store heat for use at night or during periods when it is cloudy. They can

either stand alone or be attached to houses or barns. A solar greenhouse may be an underground pit,

a shed-type structure, or a hoophouse. Large-scale producers use free-standing solar greenhouses,

while attached structures are primarily used by home-scale growers.

Passive solar greenhouses are often good choices for small growers because they are a cost-efficient

way for farmers to extend the growing season. In colder climates or in areas with long periods of

cloudy weather, solar heating may need to be supplemented with a gas or electric heating system to

protect plants against extreme cold. Active solar greenhouses use supplemental energy to move solar

heated air or water from storage or collection areas to other regions of the greenhouse. Use of solar

electric (photovoltaic) heating systems for greenhouses is not cost-effective unless you are producing

high-value crops.

Hazards due to increased weather turbulence:

• Hail

• Tornados

• High straight-line winds

• Build-up of snow, ice

The majority of the books and articles about old-style solar greenhouses were published in the 1970s

and 1980s. Since then, much of this material has gone out of print, and some of the publishers are no

longer in business. While contact information for companies and organizations listed in these

publications is probably out of date, some of the technical information contained in them is still

relevant.

The newest form of solar greenhouse, widely adopted by U.S. producers, is high tunnels. The term

glazing, as used in this publication, includes reference to polyethylene coverings for hoop houses.

Out-of-print publications often can be found in used bookstores, libraries, and through the inter-library

loan program. Some publications are also available on the Internet. Bibliofind is an excellent,

searchable Web site where many used and out-of-print books can be located.

As you plan to construct or remodel a solar greenhouse, do not limit your research to books and

articles that specifically discuss "solar greenhouses." Since all greenhouses collect solar energy and

need to moderate temperature fluctuations for optimal plant growth, much of the information on

"standard" greenhouse management is just as relevant to solar greenhouses. Likewise, much

information on passive solar heating for homes is also pertinent to passive solar heating for

greenhouses. As you look through books and articles on general greenhouse design and construction,

you will find information relevant to solar greenhouses in chapters or under topic headings that

discuss:

• energy conservation

• glazing materials

• floor heating systems

• insulation materials

• ventilation methods

In books or articles on passive solar heating in homes or other buildings, you can find useful

information on solar greenhouses by looking for chapters or topic headings that examine:

• solar orientation

• heat absorption materials

• heat exchange through "phase-change" or "latent heat storage materials"

This updated resource list includes listings of books, articles, and Web sites that focus specifically on

solar greenhouses, as well as on the topics listed above.

Related ATTRA Publications

• Season Extension Techniques for Market Gardeners

• Organic Greenhouse Vegetable Production

• Greenhouse and Hydroponic Vegetable Production Resources on the Internet

• Potting Mixes for Certified Organic Production

• Integrated Pest Management for Greenhouse Crops

• Herbs: Organic Greenhouse Production

• Plug and Transplant Production for Organic Systems

• Compost Heated Greenhouses

• Root Zone Heating for Greenhouse Crops

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Basic Principles of Solar Greenhouse Design

Solar greenhouses differ from conventional greenhouses in the following four ways.(1) Solar

greenhouses:

• have glazing oriented to receive maximum solar heat during the winter.

• use heat storing materials to retain solar heat.

• have large amounts of insulation where there is little or no direct sunlight.

• use glazing material and glazing installation methods that minimize heat loss.

• rely primarily on natural ventilation for summer cooling.

Understanding these basic principles of solar greenhouse design will assist you in designing,

constructing, and maintaining an energy-efficient structure. You can also use these concepts to help

you search for additional information, either on the "Web," within journals, or in books at bookstores

and libraries.

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Solar Greenhouse Designs

Attached solar greenhouses are lean-to structures that form a room jutting out from a house or barn.

These structures provide space for transplants, herbs, or limited quantities of food plants. These

structures typically have a passive solar design.

Freestanding solar greenhouses are large enough for the commercial production of ornamentals,

vegetables, or herbs. There are two primary designs for freestanding solar greenhouses: the shed type

and the hoophouse. A shed-type solar greenhouse is oriented to have its long axis running from east to

west. The south-facing wall is glazed to collect the optimum amount of solar energy, while the north-

facing wall is well-insulated to prevent heat loss. This orientation is in contrast to that of a

conventional greenhouse, which has its roof running north-south to allow for uniform light distribution

on all sides of the plants. To reduce the effects of poor light distribution in an east-west oriented

greenhouse, the north wall is covered or painted with reflective material.(2)

Freestanding shed-type solar greenhouses(2)

For cold winters, northern latitudes, and year-round use:

• steep north roof pitched to the highest summer sun angle for maximum year-round light reflection onto plants;• vertical north wall for stashing heat storage.• 40-60° sloped south roof glazing.• vertical kneewall high enough to accommodate planting beds and snow sliding off roof.• end walls partially glazed for added light.• The Brace Institute design continues the north roof slope down to the ground (eliminating the north wall), allowing for more planting area in ground, but no heat storage against the north wall.

For cold winters, middle U.S. latitudes, and year-round use (similar to the design popularized by Domestic Technology Institute, see Resources for plans and address):

• 45-60° north roof slope.• vertical north wall for stacking heat storage.• 45° south roof glazing.• vertical kneewall.• part of end walls glazed for additional light.

For milder winters, southern U.S. latitudes, and year-round use where less heat storage is needed:

• 45-70° north roof slope—roof slope steeper and north wall shorter if less space is needed for stacking heat storage.• roof can extend down to ground, eliminating back kneewall if no storage is use.• 20-40° south roof glazing.• front kneewall as high as is needed for access to beds in front.• most of end walls glazed for additional light.

Freestanding hoophouses are rounded, symmetrical structures. Unlike the shed-type solar

greenhouses, these do not have an insulated north side. Solarization of these structures involves

practices that enhance the absorption and distribution of the solar heat entering them. This typically

involves the collection of solar heat in the soil beneath the floor, in a process called earth thermal

storage (ETS), as well as in other storage materials such as water or rocks. Insulation of the

greenhouse wall is important for minimizing heat loss. Heat absorption systems and insulation

methods are discussed in detail in the following sections.

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Solar Heat Absorption

The two most critical factors affecting the amount of solar heat a greenhouse is able to absorb are:

• The position or location of the greenhouse in relation to the sun

• The type of glazing material used

Solar Orientation

Since the sun's energy is strongest on the southern side of a building, glazing for solar greenhouses

should ideally face true south. However, if trees, mountains, or other buildings block the path of the

sun when the greenhouse is in a true south orientation, an orientation within 15° to 20° of true south

will provide about 90% of the solar capture of a true south orientation. The latitude of your location

and the location of potential obstructions may also require that you adjust the orientation of your

greenhouse slightly from true south to obtain optimal solar energy gain.(2) Some growers recommend

orienting the greenhouse somewhat to the southeast to get the best solar gain in the spring, especially

if the greenhouse is used primarily to grow transplants.(3) To determine the proper orientation for

solar buildings in your area, visit the sun chart program at the University of Oregon Solar Radiation

Monitoring Laboratory Web page. You need to know your latitude, longitude, and time zone to use this

program.

Solar path at 40° north latitude (2)

Slope of Glazing Material

In addition to north-south orientation, greenhouse glazing should be properly sloped to absorb the

greatest amount of the sun's heat. A good rule of thumb is to add 10° or 15° to the site latitude to get

the proper angle. For example, if you are in northern California or central Illinois at latitude 40° north,

the glazing should be sloped at a 50° to 55° angle (40° + 10° or 15°).(4)

Glazing

Glazing materials used in solar greenhouses should allow the greatest amount of solar energy to enter

into the greenhouse while minimizing energy loss. In addition, good plant growth requires that glazing

materials allow a natural spectrum of photosynthetically active radiation (PAR) to enter. Rough-surface

glass, double-layer rigid plastic, and fiberglass diffuse light, while clear glass transmits direct light.

Although plants grow well with both direct and diffuse light, direct light through glazing subdivided by

structural supports causes more shadows and uneven plant growth. Diffuse light passing through

glazing evens out the shadows caused by structural supports, resulting in more even plant growth.(5,

6)

Many new greenhouse glazing materials have emerged in recent decades. Plastics now are the

dominant type of glazing used in greenhouses, with the weatherability of these materials being

enhanced by ultraviolet radiation degradation inhibitors, infrared radiation (IR) absorbency, anti-

condensation drip surfaces, and unique radiation transmission properties.(7)

The method used for mounting the glazing material affects the amount of heat loss.(8) For example,

cracks or holes caused by the mounting will allow heat to escape, while differences in the width of the

air space between the two glazes will affect heat retention. Installation and framing for some glazing

materials, such as acrylics, need to account for their expansion and contraction with hot and cold

weather.(7) As a general rule, a solar greenhouse should have approximately 0.75 to 1.5 square feet of

glazing for each square foot of floor space.(1)

Table 1. Glazing Characteristics

Glass—single layerLight transmission*: 85-90%R-value**: 0.9

Advantages:• Lifespan indefinite if not broken• Tempered glass is stronger and requires fewer support bars

Disadvantages:• Fragile, easily broken• May not withstand weight of snow• Requires numerous supports• Clear glass does not diffuse light

Factory sealed double glassLight transmission*: 70-75%R-value**: double layer 1.5-2.0, low-e 2.5

Advantages:• Lifespan indefinite if not broken• Can be used in areas with freezing temperatures

Disadvantages:• Heavy• Clear glass does not diffuse light• Difficult to install, requires precise framing

Polyethylene—single layerLight transmission*: 80-90% - new materialR-value**: single film 0.87

Advantages:• IR films have treatment to reduce heat loss• No-drop films are treated to resist condensation• Treatment with ethyl vinyl acetate results in resistance to cracking in the cold and tearing• Easy to install, precise framing not required• Lowest cost glazing material

Disadvantages:• Easily torn• Cannot see through• UV-resistant polyethylene lasts only 1-2 years• Light transmission decreases over time• Expand and sag in warm weather, then shrink in cold weather

Polyethylene—double layerLight transmission*: 60-80%R-value** double films: 5ml film 1.5, 6ml film 1.7

Advantages:• Heat loss significantly reduced when a blower is used to provide an air space between the two layers• IR films have treatment to reduce heat loss• No-drop films are treated to resist condensation• Treatment with ethyl vinyl acetate results in resistance to cracking in the cold to tearing• Easy to install, precise framing not required• Lowest-cost glazing material

Disadvantages:• Easily torn• Cannot see through• UV-resistant polyethylene lasts only 1-2 years

• Light transmission decreases over time• Expand and sag in warm weather, then shrink in cold weather

Polyethylene—corrugated high densityLight transmission*: 70-75%R-value**: 2.5-3.0

Advantages:• Mildew, chemical, and water resistant• Does not yellow

Disadvantages:n/a

Laminated Acrylic/Polyester film—double layerLight transmission*: 87%R-value**: 180%

Advantages:• Combines weatherability of acrylic with high service temperature of polyester• Can last 10 years or more

Disadvantages:• Arcrylic glazings expand and contract considerably; framing needs to allow for this change in size• Not fire-resistant

Impact modified acrylic—double layerLight transmission*: 85%

Advantages:• Not degraded or discolored by UV light• High impact strength, good for locations with hail

Disadvantages:• Arcrylic glazings expand and contract considerably; framing needs to allow for this change in size• Not fire resistant

Fiber reinforced plastic (FRP)Light transmission*: 85-90% - new materialR-value**: single layer 0.83

Advantages:• The translucent nature of this material diffuses and distributes light evenly• Tedlar-treated panels are resistant to weather, sunlight, and acids• Can last 5 to 20 years

Disadvantages:• Light transmission decreases over time• Poor weather-resistance• Most flammable of the rigid glazing materials• Insulation ability does not cause snow to melt

Polycarbonate—double wall rigid plasticLight transmission*: 83%R-value**: 6mm 1.6, 8mm 1.7

Advantages:• Most fire-resistant of plastic glazing materials• UV-resistant• Very strong

Polycarbonate film—triple and quad wall rigid plasticLight transmission*: 75%R-value** triple walls: 8mm 2.0-2.1, 16mm 2.5R-value** quad wall: 6mm 1.8, 8 mm 2.1

Advantages:• Most fire-resistant of plastic glazing materials

• Lightweight• Easy to cut and install• Provides good performance for 7-10 years

Disadvantages:• Can be expensive• Not clear, translucent

• UV-resistant• Very strong• Lightweight• Easy to cut and install• Provides good performance for 7-10 years

Disadvantages:• Can be expensive• Not clear, translucent

Sources: (2, 6, 7, 13, 14)* note that framing decreases the amount of light that can pass through and be available as solar energy ** R-Value is a common measure of insulation (hr°Fsq.ft/BTU)

You need to understand four numbers when selecting glazing for solar greenhouses. Two numbers describe the heat efficiency of the glazing, and the other two numbers are important for productive plant growth. Many glazing materials include a National Fenestration Rating Council sticker that lists the following factors:

• The SHGC or solar heat gain coefficient is a measure of the amount of sunlight that passes through a glazing material. A number of 0.60 or higher is desired.

• The U-factor is a measure of heat that is lost to the outside through a glazing material. A number of 0.35 BTU/hr-ft2-F or less is desired.

• VT or visible transmittance refers to the amount of visible light that enters through a glazing material. A number of 0.70 or greater is desired.

• PAR or photosynthetically active radiation is the amount of sunlight in the wavelengths critical for photosynthesis and healthy plant growth. PAR wavelength range is 400-700 nanometers (a measure of wavelength).

Note: When choosing glazing, look at the total visual transmittance, not PAR transmittance, to see whether the material allows the spectrum of light necessary for healthy plant growth.

In addition to energy efficiency and light transmission, you should consider the following when choosing glazing materials for your greenhouse:

• Lifespan• Resistance to damage from hail and rocks• Ability to support snowload• Resistance to condensation• Sheet size and distance required between supports• Fire-resistance• Ease of installation

(Based on 6, 9, 10, 11, 12, 13, 14)

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Solar Heat Storage

For solar greenhouses to remain warm during cool nights or on cloudy days, solar heat that enters on

sunny days must be stored within the greenhouse for later use. The most common method for storing

solar energy is to place rocks, concrete, or water in direct line with the sunlight to absorb its heat.(1)

Brick or concrete-filled cinder block walls at the back (north side) of the greenhouse can also provide

heat storage. However, only the outer four inches of thickness of this storage material effectively

absorbs heat. Medium to dark-colored ceramic tile flooring can also provide some heat storage.(15)

Walls not used for heat absorption should be light colored or reflective to direct heat and light back

into the greenhouse and to provide a more even distribution of light for the plants.

Storage Materials

The amount of heat storage material required depends on your location. If you live in southern or mid-

latitude locations, you will need at least 2 gallons of water or 80 pounds of rocks to store the heat

transmitted through each square foot of glazing.(16) If you live in the northern states, you will need 5

gallons or more of water to absorb the heat that enters through each square foot of glazing.(1)

Approximately three square feet of four-inch thick brick or cinder block wall is required for each square

foot of south-facing glass.(15)

The amount of heat-storage material required also depends on whether you intend to use your solar

greenhouse for extending the growing season, or whether you want to grow plants in it year-round. For

season extension in cold climates, you will need 2 ½ gallons of water per square foot of glazing, or

about half of what you would need for year-round production.(2)

If you use water as heat-storage material, ordinary 55-gallon drums painted a dark, non-reflective

color work well. Smaller containers, such as milk jugs or glass bottles, are more effective than 55-

gallon drums in providing heat storage in areas that are frequently cloudy. The smaller container has a

higher ratio of surface area, resulting in more rapid absorption of heat when the sun does shine.(14)

Unfortunately, plastic containers degrade after two or three years in direct sunlight. Clear glass

containers provide the advantages of capturing heat better than dark metal containers and not

degrading, but they can be easily broken.(17)

Trombe walls are an innovative method for heat absorption and storage. These are low walls placed

inside the greenhouse near the south-facing windows. They absorb heat on the front (south-facing)

side of the wall and then radiate this heat into the greenhouse through the back (north-facing) side of

the wall. A Trombe wall consists of an 8- to 16-inch thick masonry wall coated with a dark, heat-

absorbing material and faced with a single or double layer of glass placed from 3/4" to 6" away from

the masonry wall to create a small airspace. Solar heat passes through the glass and is absorbed by

the dark surface. This heat is stored in the wall, where it is conducted slowly inward through the

masonry. If you apply a sheet of metal foil or other reflective surface to the outer face of the wall, you

can increase solar heat absorption by 30-60% (depending on your climate) while decreasing the

potential for heat loss through outward radiation.(10, 18)

Trombe wall.Photo: Australian Center for Renewable Energy

Water walls are a variation of the Trombe wall. Instead of a masonry wall, water-filled containers are

placed in line with the sun's rays between the glazing and the greenhouse working space. The water

can be in hard, plastic tubes or other sturdy containers, and the top of the wall can serve as a bench.

The Solviva solar greenhouse water wall consists of two 2x4 stud walls, with the studs placed two feet

on center. A one-foot spacer connects the two walls. Plastic-covered horse fence wire was then

fastened to each stud wall, and heavy-duty, dark-colored plastic water bags were inserted into the

space between the two walls. The stud walls were positioned vertically in line with the sun's rays prior

to the bags being filled with water.(19) Both the Solviva and Three Sisters Farm Web pages provide

designs for constructing solar greenhouses using water walls.

You can use rocks instead of water for heat storage. The rocks should be ½ to 1½ inches in diameter

to provide high surface area for heat absorption.(5) They can be piled in wire-mesh cages to keep

them contained. Since rocks have a much lower BTU storage value than water (35 BTU/sq.ft/°F for

rocks versus 63 for water) (13), you will need three times the volume of rocks to provide the same

amount of heat storage. Rocks also have more resistance to air flow than water, resulting in less

efficient heat transfer.(20)

Whichever material you choose to use for heat storage, it should be placed where it will collect and

absorb the most heat, while losing the least heat to the surrounding air. Do not place the thermal mass

so that it touches any exterior walls or glazing, since this will quickly draw the heat away.

Phase-change

Instead of water or rocks for heat storage, you can use phase-change materials. While phase-change

materials are usually more expensive than conventional materials, they are 5 to 14 times more

effective at storing heat than water or rocks. Thus, they are useful when space is limited. Phase-

change materials include:

• disodium phosphate dodecahydrate

• sodium thiosulfate pentahydrate

• paraffin

• Glauber's salt (sodium sulphate dcahydrate)

• calcium chloride hexahydrate and

• fatty acids (21, 22)

They absorb and store heat when they change from solid to liquid phase, and then release this heat

when they change back into a solid phase.(5) Calcium chloride hexahydrate has a heat storing

capacity 10 times that of water.(23) These materials are usually contained in sealed tubes, with

several tubes required to provide sufficient heat storage. Because of the ability of phase-change

materials to absorb high quantities of heat, they also are useful in moderating greenhouse

temperatures in the summer.

Most of the research on the use of phase-change materials for greenhouses has been conducted in

Europe, Israel, Japan, and Australia. In Israel, phase-change materials were incorporated into

greenhouse glazing, which increased heat capture and retention, but reduced the transparency of the

glazing on cloudy days when the phase change material did not become liquid.(24) At the time of

publication, two companies were identified—one in the U.S. and another in Australia—that sell

underfloor heating systems using phase-change materials.(25, 26) Phase-change drywall, currently

under research, incorporates phase-change materials inside common wallboard to increase its heat

storage capacity and could replace heavier, more expensive, conventional thermal masses used in

passive-solar space heating.(27) See the reference section for a listing of publications and Web sites

that provide additional information about phase change materials.

For more information, see the Phase Change Thermal Energy Storage Web site provides a detailed

discussion of this technology.

For many homeowners, building an attached solar greenhouse is very appealing. They believe that they can extend their garden's growing season while reducing their home heating bills. Unfortunately, there is a contradiction between the use of a greenhouse to grow plants and the use of it as a solar collector for heating the house.(9, 28)

• To provide heat for a home, a solar collector needs to be able to collect heat in excess of what plants can tolerate.

• Much of the heat that enters into a greenhouse is used for evaporating water from the soil and from plant leaves, resulting in little storage of heat for home use.

• A home heat collector should be sealed to minimize the amount of heat loss. Greenhouses, however, require some ventilation to maintain adequate levels of carbon dioxide for plant respiration and to prevent moisture build-up that favors plant diseases.

Bioshelters provide an exception to this rule. In bioshelters, the food-producing greenhouse is not an "add-on" to the house but is an integral part of the living space. Bioshelters often integrate fish or small animals with vegetable production to complete nutrient cycles. Biological control measures and plant diversity are used to manage pests in a way that is safe for people and pets in the living quarters. First pioneered by The New Alchemy Institute of East Falmouth, Massachusetts, in the 1970s, Solviva and the Three Sisters Farm carry on the bioshelter tradition.

Active Solar

An active method for solar heating greenhouses uses subterranean heating or earth thermal storage solar heating.

This method involves forcing solar-heated air, water, or phase-change materials through pipes buried

in the floor. If you use hot air for subsurface heating, inexpensive flexible drainage or sewage piping

about 10 centimeters (4 inches) in diameter can be used for the piping. Although more expensive,

corrugated drainage tubing provides more effective heating than smooth tubing, since it allows for

greater interaction between the heat in the tube and the ground. The surface area of the piping should

be equal to the surface area of the floor of the greenhouse. You can roughly calculate the number of

feet of four-inch tubing you will need by dividing the square feet of greenhouse floor area by two. Once

installed, these pipes should be covered with a porous flooring material that allows for water to enter

into the soil around them, since moist soil conducts heat more effectively than dry soil. The system

works by drawing hot air collected in the peak of the roof down through pipes and into the buried

tubing. The hot air in the tubes warms the soil during the day. At night, cool air from the greenhouse is

pumped through the same tubing, causing the warm soil to heat this air, which then heats the

greenhouse.(29, 30) For more information on this design, see Solar Greenhouses for Commercial

Growers (29), or visit the Web page of Going Concerns Unlimited, a solar energy company in Colorado.

Root-zone thermal heating with water is normally used in conjunction with gas-fired water heaters.

This system can be readily adapted to solar and works well with both floor or bench heat. Bench-top

heating with root-zone thermal tubing is widely practiced in modern greenhouse production and can

be installed easily. A permanent floor heating system consists of a series of parallel PVC pipes

embedded on 12" to 16" centers in porous concrete, gravel, or sand. Water is heated in an external

solar water heater then pumped into the greenhouse and circulated through the pipes, warming the

greenhouse floor. Containerized plants sitting directly on the greenhouse floor receive root-zone heat.

Additional information on root zone heating can be found in the ATTRA publication Root Zone Heating for

Greenhouse Crops.

The Solviva greenhouse uses a variation of active solar heating. The system in this greenhouse relies on

heat absorption by a coil of black polybutylene pipe set inside the peak of the greenhouse. The pipe

coil lays on a black background and is exposed to the sun through the glazing. A pump moves water

from a water tank, located on the floor of the greenhouse, to the coiled pipe, and back to the tank.

Water heated within the coils is capable of heating the water in the tank from 55°F to 100°F on a

sunny day. The heat contained in the water tank helps keep the greenhouse warm at night.(19)

Greenhouse management practices also can affect heat storage. For example, a full greenhouse

stores heat better than an empty one. However, almost half of the solar energy is used to evaporate

water from leaf and soil surfaces and cannot be stored for future use.(5, 31) Solar heat can be

complemented with heat from compost as described in the ATTRA publication Compost Heated Greenhouses.

Besides adding some heat to the greenhouse, increased carbon dioxide in the greenhouse

atmosphere, coming from the decomposition activities of the microorganisms in the compost, can

increase the efficiency of plant production.

While solar greenhouses can extend your growing season by providing relatively warm conditions, you should carefully select the types of plants that you intend to grow, unless you are willing to provide backup heating and lighting.

Vegetables and herbs that are suitable for production in a winter solar greenhouse include:

Cool temperature tolerant: Basil, celery, dill, fennel, kale, leaf lettuce, marjoram, mustard greens, oregano, parsley, spinach, Swiss chard, turnips, cabbage, collards, garlic, green onions, and leeks.

Require warmer temperatures: Cherry tomatoes, large tomatoes, cucumbers (European type), broccoli, edible pod peas, eggplant, and peppers.

(Based on 28)

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Insulation

Wall and Floor Insulation

Good insulation helps to retain the solar energy absorbed by thermal mass materials. Keeping heat in

requires you to insulate all areas of the greenhouse that are not glazed or used for heat absorption.

Seal doors and vents with weather stripping. Install glazing snugly within casements. Polyurethane

foams, polystyrene foams, and fiberglass batts are all good insulating materials. But these materials

need to be kept dry to function effectively. A vapor barrier of heavy-duty polyethylene film placed

between the greenhouse walls and the insulation will keep your greenhouse well insulated.(1)

Unglazed areas should be insulated to specifications of your region. For example, R-19 insulation is

specified for greenhouses in Illinois (1) and in Missouri (24), while R-21 is recommended for walls in

New Mexico.(10) The ZIP-Code Insulation Program Web site provides a free calculator for finding

recommended insulation R-values for houses based on your zip code.

Richard Nelson of SOLAROOF developed an innovative way to insulate greenhouse walls in a

hoophouse-style greenhouse. This system involves constructing a greenhouse with a double layer of

plastic sheeting as glazing. Bubble machines (such as are used to create bubbles at parties) are

installed in the peak of the greenhouse between the two layers of plastic. At least two generators

should be installed, at either end of the greenhouse. During the winter, the bubble machines face

north and blow bubbles into space between two sheets of plastic on the north side of the greenhouse

to provide R-20 or higher insulation for northern winters. During the summer, the bubble machines can

be turned to face south to provide shading against high heat.(33)

Bubble greenhouse design.

On greenhouse floors, brick, masonry, or flagstone serves as a good heat sink. However, they can

quickly lose heat to the ground if there is not an insulating barrier between the flooring and the soil. To

protect against heat loss, insulate footings and the foundation with 1- to 2-inch sheets of rigid

insulation or with a 4-inch-wide trench filled with pumice stone that extends to the bottom of the

footings. You also can insulate flooring with four inches of pumice rock. Besides insulating the floor,

this method also allows water to drain through. (16)

External Insulation

You also can insulate your greenhouse by burying part of the base in the ground or building it into the

side of a south-facing hill.(5) Straw bales or similar insulating material also can be placed along the

unglazed outside walls to reduce heat loss from the greenhouse.(34) Underground or bermed

greenhouses provide excellent insulation against both cold winter weather and the heat of summer.

They also provide good protection against windy conditions.(35) Potential problems with an

underground greenhouse are wet conditions from the water table seeping through the soil on the floor

and the entry of surface water through gaps in the walls at the ground level. To minimize the risk of

water rising through the floor, build the underground greenhouse in an area where the bottom is at

least five feet above the water table. To prevent water from entering the greenhouse from the outside,

dig drainage ditches around the greenhouse to direct water away from the walls. Also, seal the walls

with waterproof material such as plastic or a fine clay. An excellent description of how to build a simple

pit greenhouse is provided at the Web page for the Benson Institute, a division of the College of

Biology and Agriculture at Brigham Young University (BYU). This Institute has a campus in Bolivia

where students built an underground greenhouse based on local, traditional practices.(36)

The Walipini greenhouse, a traditional underground greenhouse from Bolivia.(36)

Glazing is what allows light and heat into a solar greenhouse. It can also be the greatest area for heat

loss. As mentioned previously, increasing the insulating value of glazing often decreases the amount of

sunlight entering the greenhouse. When selecting glazing for your greenhouse, look for materials that

provide both good light transmission and insulating value. For example, polyethylene films referred to

as "IR films" or "thermal films" have an additive that helps reduce heat loss.(37) Double or triple

glazing provides better insulation than single glazing. Some greenhouse growers apply an extra layer

of glazing—usually a type of film—to the interior of their greenhouses in winter to provide an extra

degree of insulation. Adding a single or double layer of polyethylene film over a glass house can

reduce heat loss by as much as 50%.(38) By using two layers of polyethylene film in plastic-film

greenhouses with a small fan blowing air between them to provide an insulating air layer, heat losses

can be reduced by 40% or more, as compared to a single layer of plastic.(39)

Greenhouse curtains limit the amount of heat lost through greenhouse glazing during the night and

on cloudy days. By installing greenhouse insulation sheets made from two-inch thick bats of

polystyrene, you can reduce by almost 90% the heat that would otherwise be lost through the glazing.

For a small greenhouse where labor is not a large constraint, you can manually install the polystyrene

sheets at night and remove them in the morning. Magnetic clips or Velcro fasteners will facilitate the

installation.(1) Alternatively, you can install thermal blankets made of polyethylene film, foam-backed

fiberglass, or foil-faced polyethylene bubble material. These blankets are supported on wire tracks and

can be raised or lowered using pulleys. While greenhouse curtains composed of thermal blankets are

usually opened and closed manually, a few manufactures have motorized roll-up systems that store

the blanket near the greenhouse peak.(5)

Solar greenhouse with solar curtains, water wall, and water heat storage on the north wall.(2)

Back to top

Ventilation

A building designed to collect heat when temperatures are cold also needs to be able to vent heat

when temperatures are warm. Air exchange also is critical in providing plants with adequate levels of

carbon dioxide and controlling humidity. Because of the concentrated air use by plants, greenhouses

require approximately two air exchanges per minute (in contrast to the one-half air exchange per

minute recommended for homes). To determine the flow requirements for your greenhouse, multiply

the volume of the greenhouse by two to get cubic feet of air exchange per minute, which is the rate

used in determining the capacity of commercial evaporative coolers.

Roof-ridge and sidewall vents provide natural ventilation. The sidewall vents allow cool air to flow into

the sides of the greenhouse, while ridge vents allow the rising hot air to escape. Some wind is

necessary for this type of ventilation system to function effectively. On still, windless days, fans are

necessary to move air through the greenhouse. The area of the venting should be equal to between

1/5 to 1/6 of the greenhouse floor area.(1)

Solar chimneys are

passive solar collectors

attached to the highest

point on the greenhouse

and are combined with

vents or openings on

either end of the

greenhouse. The

chimney has an inlet that

draws warm air from

inside the greenhouse

and an outlet that

discharges it to the

outdoors. To enhance

solar gain inside the

chimney and increase

airflow, the inner surface

of the chimney stack is glazed or painted black. A ventilator turbine added to the top of the chimney

provides an additional force to pull warm air up from inside the greenhouse.(40)

Thermal storage materials are effective in keeping a greenhouse cool in summer as well as keeping it

warm in winter. Since these materials absorb heat during the day, less heat radiates within the

greenhouse when the sun is shining. When the sun goes down, heat released from the thermal storage

materials can be vented out of the greenhouse.(2)

Removing external shading can also decrease heat build-up within the greenhouse. Shading provided

by mature trees is not recommended. Older books on solar greenhouse design (e.g., 2) argue that

deciduous trees can provide shade in the summer but allow for plenty of sunlight to enter through the

glazing in the winter after the leaves are gone. However, more recent literature notes that a mature,

well-formed deciduous tree will screen more than 40% of the winter sunlight passing through its

branches, even when it has no leaves.(31)

Active solar cooling systems include solar air-conditioning units and photovoltaics set up to run

standard evaporative cooling pads. Both are more complex and expensive to equip than passive

systems.

Putting It All Together

Designing and building a solar greenhouse can be an exciting and rewarding project. Feel free to rely

on the older literature to provide you with basic siting, design, and construction guidelines. However,

incorporating new glazing, heat storage, and insulating materials into your design can greatly enhance

the efficiency of your structure. Several consulting companies can provide you with blueprints and

A solar chimney. (2)

design assistance, often at a reasonable cost. See the Resources section for names and contact

information for these companies. Of course, you need to weigh the costs of these new technologies

against the value of your greenhouse-grown crops. As you become familiar with the principles of

passive solar design, you may want to experiment with ways of harnessing the power of the sun within

your greenhouse to produce better plants throughout the year.

Back to top

References

1. Illinois Solar Energy Association. 2002. Solar Greenhouse. ISEA Fact Sheet #9. Accessed at:

www.illinoissolar.org/

2. Alward, Ron, and Andy Shapiro. 1981. Low-Cost Passive Solar Greenhouses.

National Center for Appropriate Technology, Butte, MT. 173 p.

3. White, Joe. 1991. Growing it in a Sunpit. The Natural Farmer. Winter. p. 14.

4. Thomas, Stephen G., John R. McBride, James E. Masker, and Keith Kemble. 1984. Solar

Greenhouses and Sunspaces: Lessons Learned.

National Center for Appropriate Technology. Butte, MT. 36 p.

5. Bartok, Jr., John W. 2000. Greenhouses for Homeowners and Gardeners. NRAES-137. Cornell

University, Ithaca, NY. 214 p.

6. Giacomelli, Gene A. 1999. Greenhouse coversing systems—User considerations. Cook College.

Rutgers University. Accessed at: http://AESOP.RUTGERS.EDU/~ccea/publications.html

7. Giacomelli, Gene A. 1999. Greenhouse glazings: Alternatives under the sun. Department of

Bioresource Engineering. Cook College. Rutgers University. Accessed at:

http://AESOP.RUTGERS.EDU/~ccea/publications.html

8. Bartok, Jr., John W. 2001. Energy Conservation for Commercial Greenhouses. NRAES-3. Cornell

University, Ithaca, NY. 84 p.

9. BTS. 2001. Passive Solar Design. Technology Fact Sheet. U.S. Department of Energy. Office of

Building Technology, State and Community Programs. Accessed at:

apps1.eere.energy.gov/buildings/publications/pdfs/building_america/29236.pdf

[PDF/232K]

10.Luce, Ben. 2001. Passive Solar Design Guidelines for Northern New Mexico. New Mexico Solar

Energy Association. Accessed at:

www.nmsea.org/Curriculum/Courses/Passive_Solar_Design/Guidelines/Guidelines.htm

11.NREL. 2001. Passive Solar Design for the Home. Energy Efficiency and Renewable Energy

Clearinghouse. National Renewable Energy Laboratory. U.S. Department of Energy. Accessed

at: www.nrel.gov/docs/fy01osti/27954.pdf [PDF/216K]

12.BTS. 2001. Passive Solar Design. Technology Fact Sheet. U.S. Department of Energy. Office of

Building Technology, State and Community Programs. Accessed at:

www.nrel.gov/docs/fy01osti/29236.pdf [PDF/232K]

13.Smith, Shane. 2000. Greenhouse Gardener's Companion: Growing Food and Flowers in Your

Greenhouse or Sunspace. Fulcrum Publishers. 2nd edition. 544 pages. Excerpts accessed at:

www.greenhousegarden.com/energy.htm

14. Nuess, Mike. 1997. Designing and building a solar greenhouse or sunspace. Washington State

University Energy Program.

15.Williams, Sue E., Kenneth P. Larson, and Mildred K. Autrey. 1999. Sunspaces and Solar

Porches. The Energy Event. Oklahoma State Cooperative Extension Service. A hard copy can

be purchased via the following website www.osuums.com/ASPFiles/inventfind.asp?s=.

16.Anon. n.d. Solar Greenhouse Plans and Information. Sun Country Greenhouse Company.

Accessed at: www.hobby-greenhouse.com/FreeSolar.html

17.North Carolina Solar Center. 2000. Do It Yourself Solar Applications: For Water and Space

Heating. North Carolina Solar Center. Energy Division North Carolina Department of

Commerce. Accessed at: www.ncsc.ncsu.edu/information_resources/factsheets/23lowcst.pdf

[PDF/713K]

18. NREL. 1999. Building a Better Trombe Wall. National Renewable Energy Laboratory.

19. Edey, Anna. 1998. Solviva: How to Grow $500,000 on One Acre and Peace on Earth. Trailblazer

Press, Vineyard Haven, MA. 225 p.

20.Pin, Nick. 1995. Solar closets in a nutshell. Listserv message. Archived at:

www.ibiblio.org/london/renewable-energy/solar/Nick.Pine/msg00026.html

21.Solar Technologies. Accessed at: www.alaskasun.org/pdf/SolarTechnologies.pdf

(PDF/328K]

22.Gates, Jonathan. 2000. Phase Change Material Research. Accessed at:

http://freespace.virgin.net/m.eckert/index.htm

23. Baird, Stuart, and Douglas Hayhoe. 1983. Passive Solar Energy. Energy Fact Sheet.

24. Korin, E., A. Roy, D. Wolf, D. Pasternak, and E. Rappaport. 1987. A novel passive solar

greenhouse based on phase-change materials. International Journal of Solar Energy. Volume 5.

p. 201-212.

25.PCM Thermal Solutions. Underfloor heating. Accessed at: www.pcm-

solutions.com/under_app.html

26. TEAP Energy. 2002. PCM Energy Efficiency.

27. EREC. n. d. Phase Change Drywall. EREC Reference Briefs. U.S. Department of Energy. Office of

Energy Efficiency and Renewable Energy. (document no longer available on web)

28.Butler, Nancy J. 1985. A Home Greenhouse—Dream or Nightmare? Weed 'Em and Reap; Feb.-

March. MSU Cooperative Extension Service. Accessed at: www.hobby-

greenhouse.com/UMreport.htm

29. Monk, G.J., D.H. Thomas, J.M. Molnar, and L.M. Staley. 1987. Solar Greenhouses for Commercial

Growers. Publication 1816. Agriculture Canada. Ottawa, Canada.

30. Puri, V.M., and C.A. Suritz. 1985. Feasibility of subsurface latent heat storage for plant root

zone and greenhouse heating. American Society of Agricultural Engineers (Microfiche

collection) 20 p.

31.NREL. 1994. Sunspace Basics. Energy Efficiency and Renewable Energy Clearinghouse.

National Renewable Energy Laboratory. U.S. Department of Energy. Accessed at:

www1.eere.energy.gov/office_eere/pdfs/solar_fs.pdf [PDF/220K]

32. Thomas, Andrew L., and Richard J. Crawford, Jr. 2001. Performance of an Energy-efficient,

Solar-heated Greenhouse in Southwest Missouri. Missiouri Agricultural Experiment Station.

Missouri University College of Agriculture, Food, and Natural Resources.

33.Nelson, Richard. Sola Roof Garden. Accessed at:

http://solaroof.org/wiki/SolaRoof/SolaRoofGarden/

34.Cruickshank, John. 2002. Solar Heated Greenhouses with SHCS. Growing Concerns. Accessed

at: www.sunnyjohn.com/indexpages/shcs_greenhouses.htm

35.Geery, Daniel. 1982. Solar Greenhouses: Underground. TAB Books, Inc.

Blue Ridge Summit, PA. 400 p.

36.Benson Institute. n.d.. The Pankar-huyu and Building a Pankar-huyu. Accessed at:

http://benson.byu.edu/Publication/BI/Lessons/volume22/pankar.html and

http://benson.byu.edu/Publication/BI/Lessons/volume22/building.html

37.Anon. 2002. Greenhouse Glazing. Horticultural Engineering, Rutgers Cooperative Extension,

Volume 17, No. 1. Accessed at: www.rosesinc.org/ICFG/Join_ICFG/2002-

03/Greenhouse_Glazing.asp

38. Aldrich, Robert A., and John W. Bartok, Jr. 1989. Greenhouse Engineering. NRAES-33. Northeast

Regional Agricultural Engineering Service, Cornell University. 203 p.

39. Hunt, John N. 1988. Saving energy—North Carolina style. Greenhouse Grower. March.

40. Gilman, Steve. 1991. Solar ventilation at Ruckytucks Farm. The Natural Farmer. Winter. p. 15.

Back to top

Resources

Kansas State University Recommended High Tunnel Resources. Ted Carey. 2008.

• K State Plans for 4-season hoophouseswww.hightunnels.org Note: www.hightunnels.org has links to suppliers and multiple sources of information-including the high tunnels listserv, Penn State Web site, and construction designs. The hightunnel listserv allows participants to ask questions of all members of the list. Complete archives are stored on-line.

• Blomgren, T., and T. Frisch. 2007. High Tunnels: Using low-cost technology to increase yields, improve quality and extend the season. University of Vermont Center for Sustainable Agriculture.www.uvm.edu/sustainableagriculture/hightunnels.html

• Coleman, Eliot. 1998. The Winter Harvest Manual.Order from: Four Season Farm, 609 Weir Cover Road, Harborside, ME. $15.00.

• Growing for Market. [n.d.] Hoophouse handbook. Fairplain Publications, Lawrence, KS.Order from: Fairplain, P.O. Box 3747, Lawrence, KS 66046.www.growingformarket.com; 800-307-8949. Much of the content reprinted from Growing for Market.

• Heidenreich, C. et al. 2007. High Tunnel Raspberries and Blackberries. Cornell University.www.fruit.cornell.edu/Berries/bramblepdf/hightunnelsrasp.pdf

• Jett, Lewis. High Tunnel Tomato Production. University of Missouri Extension. Pub. MI70.

• Jett, L. High Tunnels Melon and Watermelon Production. University of Missouri Extension. Pub. M173.

• Lamont et al. 2004. Production of Vegetables, Strawberries and Cut Flowers Using Plasticulture. NRAES-133. Ithaca, NY.

• Penn State High Tunnel Production Manual. 2004. www.plasticulture.org/publications/tunnel.pdf. $31.00.

• Wiediger, Paul and Alison. [n.d.] Walking to Spring.Order from: Au Naturel Farm, 3298 Fairview Church Road, Smiths Grove, KY 42171. $18.50.

Books

• Solar Greenhouses

• Energy Conservation in Greenhouses

• Passive Solar Home Design

Note: Many of the books listed below are out of print. You may be able to locate these books at a

public library or in a good used bookstore. Bibliofind is an excellent, searchable Web site where many

used and out-of-print books can be located.

Solar Greenhouses

Anon. 1980. A Solar Adapted Greenhouse Manual and Design. Miller-Solsearch, Charlottetown, PEI,

Canada.

Anon. 1979. The Canadian Solar Home Design Manual. Overview,

Wolfville, Nova Scotia. 71 p.

Babcock, Joan, et al. 1981. A Place in the Sun: A Guide to Building an Affordable Solar Greenhouse.

R.J.K. Solar, Gillette, NJ. 28 p.

Craft, Mark A. (Editor). 1983. Winter Greens: Solar Greenhouses for Cold Climates.

Firefly Books. Scarborough, Ont. 262 p. (Out of Print).

Clegg, Peter. 1978. The Complete Greenhouse Book: Building and Using Greenhouses from Cold-

Frames to Solar Structures. Storey Books. Pownal, VT. 280 p. (Out of print).

Conserver Society Products Cooperative. 1979. Solar Greenhouse Workbook.

Conserver Society Cooperative, Ottawa, Canada. 43 p.

DeKorne, James B. 1992. The Hydroponic Hot House: Low-Cost, High Yield Greenhouse Gardening.

Breakout Productions, Incorporated 178 p.

An illustrated guide to alternative-energy greenhouse gardening. It includes directions for building

several different greenhouses.

Edey, Anna. 1998. Solviva: How to Grow $500,000 on One Acre and Peace on Earth. Trailblazer Press,

Vineyard Haven, MA. 225 p.

One of few recent books written on solar greenhouses. Available for $35 from:

Solviva

RFD 1 Box 582

Vineyard Haven, MA 02568

508-693-3341

508-693-2228 FAX

solviva@vineyard.net

Ellwood, Charles C. How to Build and Operate Your Greenhouse: Growing Methods, Hydroponics,

Nutrient Formulas, Plans, Costs, Heating and Cooling, Introduction to Solar heating. H.P. Books.

Tucson, AZ. 144 p. (Out of print).

Freeman, Mark. 1997. Building Your Own Greenhouse. Stackpole Books,

Mechanicsburg, PA. 208 p.

A guide to designing and constructing cold frames, free-standing greenhouses, and attached to the

house solar greenhouses. Available for $18.95 from:

Stackpole Books

5067 Ritter Rd.

Mechanicsburg, PA 17055

800-732-3669

Fontanetta, John. 1979. Passive Solar Dome Greenhouse Book. Storey Books.

Pownal, VT. (Out of print).

Fuller, R.J. 1992. Solar Greenhouses for the Home Gardener. Victorian Dept. of Food and Agriculture,

Melbourne, Australia. 27 p.

Geery, Daniel. 1982. Solar Greenhouses: Underground. TAB Books, Blue Ridge Summit, PA. 400 p.

Focuses on earth-sheltered solar greenhouse structures. Good information on design, function,

construction, and operation of greenhouses. Many useful tables and charts. (Out of print).

Hayes, John (ed.). 1979. Proceedings from the Conference on Energy-Conserving, Solar-Heated

Greenhouses. Held in Plymouth, MA, April, 1979. New England Solar Energy Association, Brattleboro,

VT. 328 p.

Head, William. 1984. Fish Farming in Your Solar Greenhouse. Amity Foundation, Eugene, OR. 50 p. (Out

of print).

Magee, Tim. 1979. A Solar Greenhouse Guide for the Pacific Northwest.

Ecotope, Seattle, WA. 91 p.

Available for $6 from:

Ecotope

2812 E. Madison

Seattle, WA 98112

206-322-3753

Mazria, Edward. 1979. The Passive Solar Energy Book. Rodale Press, Emmaus, PA. 435 p. (Out of print,

but usually available from used book sellers).

McCullagh, James C. (ed.) 1978. The Solar Greenhouse Book. Rodale Press, Emmaus, PA. 328 p.

Comprehensive overview of small attached, pit, and free-standing solar greenhouses. Out of print, but

usually available from used booksellers.

Monk, G.J., D.H. Thomas, J.M. Molnar, and L.M. Staley. 1987. Solar Greenhouses for Commercial

Growers. Publication 1816. Agriculture Canada, Ottawa, Canada. 48 p.

Nearing, Helen, and Scott Nearing. 1977. Building and Using Our Sun-Heated Greenhouse: Grow

Vegetables All Year-Round. Storey Books, Pownal, VT. 148 p. (Out of print).

Shapiro, Andrew. 1985. The Homeowner's Complete Handbook for Add-On Solar Greenhouses and

Sunspaces. Rodale Press, Emmaus, PA. 355 p.

Updates and expands on material in The Solar Greenhouse Book (see above). (Out of print).

Smith, Shane. 1982. The Bountiful Solar Greenhouse. John Muir Publications. Santa Fe, NM. 221 p. (Out

of print).

Stone, Greg. 1997. Building a Solar-Heated Pit Greenhouse. Storey Communications,

Pownal, VT. 32 p. (Out of print).

Strickler, Darryl J. 1983. Solarspaces : How (and Why) to Add a Greenhouse, Sunspace, or Solarium to

Your Home. Van Nostrand Reinhold Co., New York, NY. 154 p. (Out of print).

Taylor, Ted M. 1999. Secrets to a Successful Greenhouse and Business : A Complete Guide to Starting

and Operating A High-Profit Organic or Hydroponic Business That Benefits the Environment.

GreenEarth Publishing, Melbourne, FL. 280 p.

Includes solar greenhouse design plans as well as greenhouse operation and business development

information. Ordering information available at: www.greenhouse.net

Thomas, Stephen G., John R. McBride, James E. Masker, and Keith Kemble. 1984. Solar Greenhouses

and Sunspaces: Lessons Learned. National Center for Appropriate Technology. Butte, MT. 36 p. (Out of

print).

Williams, T. Jeff, Susan Lang, and Larry Hodgson. 1991. Greenhouses: Planning, Installing and Using

Greenhouses. Ortho Books, San Ramon, CA. 112 p.

Yanda, William F. 1976. An Attached Solar Greenhouse. Lightning Tree Press, Boulder, CO. 18 p. (Out

of print).

Yanda, William F., and Rick Fisher. 1980. The Food and Heat Producing Solar Greenhouse: Design,

Construction, and Operation. John Muir Publishing, Santa Fe, NM. 208 p.

(Out of print).

Energy Conservation in Greenhouses

Aldrich, Robert A., and John W. Bartok, Jr. 1989. Greenhouse Engineering. NRAES-33. Cornell

University, Ithaca, NY. 203 p.

Provides a comprehensive treatment of the design and construction of medium- to large-scale

greenhouses, with over 60 tables and 100 diagrams. $30.

Bartok, Jr., John W. 2001. Energy Conservation for Commercial Greenhouses. NRAES-3. Cornell

University, Ithaca, NY. 84 p.

Reviews the merits and limitations of current energy-conservation strategies for commercial

greenhouses. Topics covered include principles of heat loss, site selection and modification,

construction materials, insulation, fuels and heating, ventilation and cooling, space utilization, utilities,

strategies for reducing trucking costs, and managing for efficiency.

Bartok, Jr., John W. 2000. Greenhouses for Homeowners and Gardeners. NRAES-137. Cornell University,

Ithaca, NY. 214 p.

Covers every aspect of designing and constructing a home greenhouse. Eight chapters discuss the

following topics: greenhouse basics, selecting a greenhouse, greenhouse planning, framing materials

and glazing, greenhouse layouts and equipment, the greenhouse environment, window greenhouses

and growth chambers, and garden structures.

The three books listed above are available from:

Natural Resource, Agriculture, and Engineering Service (NREAS)

152 Riley-Robb Hall

Ithaca, New York 14853-5701

607-255-7654

607-254-8770 FAX

NRAES@cornell.edu

Bond, T.E., J.F. Thompson, and Ray F. Hasek. 1985. Reducing Energy Costs in California Greenhouses.

Leaflet 21411. Cooperative Extension University of California. 24 p.

Passive Solar Home Design

Anderson, Bruce, and Malcolm Wells. 1981. Passive Solar Energy: The Home-owner's Guide to Natural

Heating and Cooling. Brick House Pub. Co. 197 p.

Crosbie, Michael J. (ed.) 1998. The Passive Solar Design and Construction Handbook.

John Wiley and Sons Ltd., New York. 291 p.

Creech, Dennis B. 1988. Homeowner's Guide to Energy Efficient and Passive Solar Homes. DIANE

Publishing Co.

Kachadorian, James. 1997. The Passive Solar House: Using Solar Design to Heat and Cool Your Home.

Chelsea Green Publishing Co. White River Junction, VT $25.

Available from The Solar Energy Organization Web page.

Levy, M. Emanuel, Deane Evans, and Cynthia Gardstein. 1983. The passive solar construction

handbook: featuring hundreds of construction details and notes, materials specifications, and design

rules of thumb. Rodale Press, Emmaus, PA. 328 p.

Back to top

Articles, Fact Sheets, and Web Sites

• Solar Greenhouse Designs and Consultation

• Greenhouse Glazing

• Greenhouse Curtains

• Solar Chimneys

• Phase-Change Materials

• General Greenhouse Information

• Greenhouse Technical and Trade Publications

• Solar Energy Organizations: National

• Solar Energy Organizations: State

Solar Greenhouse Designs and Consultation

The Bioshelter at Three Sisters Farm

The bioshelter includes a solar greenhouse, poultry housing, potting room, seed and tool storage, an

equipment storage "barn," a kitchen for packing produce, compost bins, a reference library and living

spaces. A full report of the bioshelter design costs $8.00. Three Sisters Permaculture Design also offers

consultation on solar greenhouse design, construction and management.

The Green Greenhouse

An excellent site, funded partially by the Northeast SARE, provides detailed design blueprints,

materials list, construction suggestions, and performance information for a solar greenhouse.

Growing Concerns, Unlimited. Solar Greenhouses

Provides design and construction consulting services for building solar greenhouses and homes.

Specializes in subterranean solar heat systems.

Hobby Greenhouse Association

Sells a Directory of Manufacturers: Hobby Greenhouses, Solariums, Sunrooms, and Window

Greenhouses for $2.50. Has links to many greenhouse manufacturers' Web pages. A one-year

membership to the association costs $15 and includes a subscription to Hobby Greenhouse, a

quarterly magazine, and Hobby Greenhouse News, a quarterly newsletter.

Hobby Greenhouse Association

8 Glen Terrace

Bedford, MA 01730-2048

781-275-0377

Passive Solar Greenhouse

Provides consulting services and passive solar greenhouse plans that have passed building codes for

New Mexico. Blueprints include lists of materials and where to purchase them.

Solar Components Corporation

Solar greenhouse kits as well as blueprints and materials for "build-your-own" solar greenhouses.

Solar Components Corporation

121 Valley Street

Manchester, NH 03103

603-668-8186

Sundance Supply

Provides information on greenhouse design and installation. Sells materials needed for constructing

and maintaining greenhouses.

Sunglo Solar Greenhouses

214 21st Street SE

Auburn, WA 98002

800-647-0606

Free catalog of greenhouse kits available.

Greenhouse Glazing

Giacomelli, Gene A. 1999. Greenhouse coversing systems - User considerations. Greenhouse glazings:

Alternatives under the sun. Cook College. Rutgers University.

http://AESOP.RUTGERS.EDU/~ccea/publications.html

Giacomelli, G.A., and W.J. Roberts. 1993. Greenhouse covering systems. HortTechnology. Volume 3,

no. 1. p. 50-58.

Roberts, W.J. 1989. Greenhouse glazing. In: K.V. Garzoli (ed.) Energy Conservation and Solar Energy

Utilization in Horticultural Engineering. Acta horticulturae. Volume 257. p. 161-168. Ordering

information at: www.actahort.org/books/257/index.htm

Meyer, J. 1985. Greenhouse Construction and Covering Materials. ISHS Acta Horticulturae 170.

Ordering information at: www.actahort.org/books/170/

Efficient Windows Collaborative

National Festration Council. 2002

Greenhouse Curtains

National Greenhouse Manufactures Association. Helpful Hints: Internal and External Greenhouse

Curtain Systems [PDF/125K]

Agri-tech. Energy Curtain

FAQs—Internal & External Greenhouse Curtain Systems. Griffin Greenhouse and Nursery Supply

National Greenhouse Manufacturers Association

Solar Chimneys

Anon. 1986. Solar chimney for low-cost desert cooling. Popular Science. May. p. 16B-17C.

Abrams, Don. 1984. The latest on solar chimneys. Rodale's New Shelter. August. p. 10-11.

Abrams, Donald W. 1986. Low-Energy Cooling: A Guide to the Practical Application of Passive Cooling

and Cooling Energy Conservation Measures. Van Nostrand Reinhold Co., New York, NY. p. 126-131,

150-161.

Burton, John, and Jeff Reiss. 1981. Project: A solar chimney. p. 623-627. In: Joe Carter (ed.) Solarizing

Your Present Home. Rodale Press, Emmaus, PA.

Cunningham, W.A., and T.L. Thompson. 1988. Passive greenhouse cooling.

Greenhouse Grower. April. p. 19-20.

Phase-change Materials

Verner, Carl. 1997. Phase Change Thermal Energy Storage.

http://freespace.virgin.net/m.eckert/carl_vener's_dissertation.htm

General Greenhouse Information

Abraham, Doc and Katy. 1993. What to look for in a greenhouse. Consumers' Research. January. p. 31-

35.

Good introduction to greenhouses in general.

Dickerson, Lizzy. 1992. The stone-built, bermed greenhouse. Maine Organic Farmer & Gardener. May-

June. p. 16-17.

Hofstetter, Bob. 1989. Tunnels of plenty. The New Farm. November-December. p. 36-39.

Hofstetter, Bob. 1990. The New Farm's greenhouse guide. The New Farm. September-October. p. 32-

36.

von Zabeltitz, Christian. 1990. Greenhouse construction in function of better climate control. Acta

Horticulturae Vol. 263. p. 357-366

Greenhouse Technical and Trade Publications

Acta Horticulturae

Journal of the International Society for Horticultural Science

ISHS Secretariat

P.O. Box 500

3001 Leuven 1, Belgium

Greenhouse Grower

Meister Publishing Company

37733 Euclid Ave.

Willoughby, OH 44094

216-942-2000

GM Pro (formerly Greenhouse Manager)

Branch-Smith Publishing

120 St. Louis Ave.

Fort Worth, TX 76101

800-433-5612

817-882-4121 FAX

www.greenbeam.com

NM Pro (formerly Nursery Manager)

Branch-Smith Publishing

120 St. Louis Ave.

Fort Worth, TX 76101

800-433-5612

817-882-4121 FAX

www.greenbeam.com

GrowerTalks

Ball Publishing

335 N. River Street

PO Box 9

Batavia, IL 60510-0009 USA

630-208-9080

630-208-9350 FAX

Greenhouse Product News

Scranton Gillette Communications, Inc.

380 E. Northwest Hwy.

Des Plaines, IL 60016-2282

708-290-6622

Solar Energy Organizations: National

American Solar Energy Society

2400 Central Ave., G-1

Boulder, CO 80301

303-443-3130

Publishes Solar Today magazine and an annual membership directory; $70 annual membership fee.

National Renewable Energy Laboratory. Energy Efficiency and Renewable Energy. U.S. Department of

Energy. Passive Solar Heating, Cooling and Daylighting.

www.eere.energy.gov/de/cs_passive_solar.html

Fact sheets include:

Passive Solar Design for the Home

U.S. Department of Energy. Office of Building /Technology, State and Community Programs.

Publications.

Fact sheets include:

Passive Solar Design

The Solar Energy Research Facility

Renewable Energy Policy Project and Center for Renewable Energy and Sustainable Technology

Links to national, state, and international solar energy associations.

Database of State Incentives for Renewable Energy (DSIRE)

Links to state, local, utility, and selected federal incentives that promote renewable energy.

Solar Energy Organizations: State

Illinois Solar Energy Association

Indiana: Midwest Renewable Energy Association

New Mexico Solar Energy Association

North Carolina Solar Center

Other sources of solar greenhouse factsheets have, in the past, included Oklahoma State Cooperative

Extension Service, the Solar Energy Association of Oregon, the Texas State Energy Conservation

Office, and the Texas Solar Energy Society. The best way to find current information on such

organizations is by doing a Web search.

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Computer Software

EREC. n. d. Computer Software for Solar Energy Analysis and System Design. EREC Reference Briefs.

U.S. Department of Energy. Office of Energy Efficiency and Renewable Energy.

www.eere.energy.gov/buildings/tools_directory/software.cfm/ID=88/

Energy-10. A software package for solar energy design. Available from Solar Building Industries

Council. www.sbicouncil.org/store/index.php

SUN_CHART™. A computer software that calculates and screen plots both cylindrical and polar

suncharts for any desired latitude. Available from:

Optical Physics Technologies

P.O. Box 11276

Tucson, AZ 85734

Acknowledgements: ATTRA agricultural specialists Janet Bachmann, Mike Morris, and Steve Diver

provided excellent reviews of this document. Steve's many files on solar greenhouses were extremely

useful in identifying the breadth of solar greenhouse designs.

Solar Greenhouses

By Barbara Bellows, updated by K. Adam

NCAT Agriculture Specialists

Mary Ann Thom, HTML Production

© NCAT

IP142

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This page was last updated on: February 25, 2011

Serele solareBarbara Bellows, actualizate de către K. Adam Specialişti în agricultură NCAT Publicat 2008© NCAT IP142

Abstract

Această listă de resursă discută despre principiile de bază ale proiectare

solare cu efect de seră, precum şi opţiuni diferite de construcție de

materiale. Cărţi, articole şi site-uri Web şi programe de calculator

relevante pentru proiectare de seră solare sunt furnizate într-o listă de

resursă.

Cuprins

• Introducerea

• Principiile de bază ale solare cu efect de seră Design

• Solare cu efect de seră Designs

• Solare de absorbție de energie termică

• Solare de stocare de căldură

• Izolare

• Ventilație

• Pune-O împreună

• Referinţe

• Resurse

○ Cărţi

○ Articole, fișele şi site-uri Web

○ Programe de calculator

Introducerea

Începând cu 2000, U.S. cu efect de seră cultivatorilor au din ce în ce adoptat tuneluri de mare ca

tehnologie cu efect de seră solare preferată. Rame rigide și geamurile sunt încă comune în regiuni ale

Europei și controlate de clima operaţiunile în Mexic şi Caraibe care produc de acri de culturilor de iarnă

pentru piețele din America de Nord. (Pentru mai multe pe tehnologia de climat controlat, consultaţi

Linda Calvin și Roberta Cook. 2005. "Tomate de seră Schimbarea dinamica a industriei din America de

Nord de tomate proaspete." AmberWaves. Aprilie. Vol. 3, nr. 2.).

Toate sere colecta energia solară. Serele solare sunt concepute pentru a colecta energia solară în

timpul zile insorite dar, de asemenea, pentru a stoca energie termică pentru folosirea pe timp de

noapte sau în timpul perioadelor când este tulbure. Acestea fie poate sta singur sau se anexează case

Kansas City Center pentru agricultură urbane.Foto: NCAT

sau hambare. O seră solare pot fi o groapă subteran, o structură de tip de magazie sau un hoophouse.

Producătorii pe scară largă folosesc nefixată solare sere, în timp ce ataşat structurile sunt în primul

rând folosite de cultivatori de scară de acasă.

Pasivă solare sere sunt adesea bune alegeri pentru cultivatorii mici, deoarece acestea sunt un cost-

eficient mod pentru agricultorii să extindă sezonului de creştere. În rece climate sau în zonele cu

perioade lungi de vreme tulbure, încălzire solare pot trebuie să fie completate cu un gaz sau un sistem

de încălzire electrică necesară protejarea plantelor împotriva frigului. Serele solare activă utilizaţi

suplimentare de energie pentru a muta solare de aer încălzit sau apă din zonele de depozitare sau

colectarea alte regiuni de seră. Utilizarea solare electrice (fotovoltaice) sisteme pentru serele de

încălzire nu este rentabilă decât dacă sunt producătoare de culturi de mare valoare.

Riscuri datorate turbulenţe crescut de vreme:

• Grindină

• Tornados

• Vânturile puternice liniară

• Acumulării de zăpadă, gheaţă

Majoritate de cărţi şi articole despre sere solare stil vechi au fost publicate în anii 1970 și 1980. De

atunci, mare parte din acest material a plecat din imprimare şi unele dintre editorii nu mai sunt în

afaceri. În timp ce informaţii de contact pentru companii si organizatii enumerate în aceste publicaţii

este probabil neactualizat, unele dintre informații tehnice conţinute în ele este încă relevante.

Cele mai noi forma de seră solare, adoptat pe scară largă de către producătorii de U.S., este mare de

tuneluri. Termenul pentru geamurile, astfel cum este utilizat în prezenta publicație, include trimitere la

Îmbrăcămințile de polietilenă pentru caselor cercui.

Adesea publicaţii afară de imprimare poate fi găsit în librăriile utilizate, biblioteci, şi prin programul de

inter-library de împrumut. Unele publicaţii sunt de asemenea disponibile pe Internet. Bibliofind este un

excelent, căutabil site Web unde multe folosite şi cărţi afară de imprimare poate fi localizată.

După cum aveţi de gând să construiască sau remodela o seră solare, nu limita dumneavoastră de

cercetare de cărţi şi articole care în mod specific discuta "solare sere." Deoarece toate sere colecta

energia solară și necesitatea de a moderată fluctuațiilor de temperatură pentru creșterea plantei

optimă, mult de informații asupra gestionării de seră "standard" este doar de relevante pentru sere

solare. De asemenea, mai multe informaţii despre pasivă solare încălzire pentru casele este de

asemenea pertinente pentru încălzire solare pasive pentru sere. Aşa cum te uiţi prin cărţi şi articole

despre generale cu efect de seră proiectarea și construcția, veţi găsi informaţii relevante pentru sere

solare în capitolele sau sub titlurile de subiect care discuta:

• conservarea energiei

• materialele pentru sticla

• sisteme de încălzire podea

• materiale izolante

• metode de ventilație

În cărți sau articole pe pasivă solare încălzire în casele sau alte clădiri, puteţi găsi informaţii utile pe

sere solare prin căutarea de capitole sau titlurile de subiect care examinează:

• orientarea solare

• materiale de absorbție căldură

• schimb de căldură prin "faza-schimbare" sau "materiale de stocare căldură latentă"

Această listă de resursă actualizat include listări de cărţi, articole şi site-uri Web care se concentrează

în special asupra solare sere, precum şi pe subiecte enumerate mai sus.

Conexe ATTRA publicaţii

• Sezonul extinderea tehnici pentru pia ț a gradinari

• Productia ecologica de legume cu efect de seră

• Cu efect de seră şi resursele de producţie vegetală Hydroponic pe Internet

• Potting adaos pentru productia ecologica de certificate

• Management integrat al daunatorilor pentru culturile cu efect de seră

• Plante: Productia ecologica, cu efect de seră

• Conectaţi productia de rasaduri pentru sistemul ecologic

• Compost de încălzit sere

• Zona de rădăcină de încălzire pentru culturile cu efect de seră

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Principiile de bază ale solare cu efect de seră Design

Serele solare diferă de sere convenţionale în următoarele patru moduri.(1) Solar sere:

• au geamuri orientate spre primi căldură solare maximă în timpul iernii.

• Utilizaţi căldură depozitarea materialelor pentru a reține căldura solară.

• au cantităţi mari de izolare în cazul în care există foarte puţin sau nu lumina solară directă.

• Utilizaţi material geamurile şi metode de instalare geamurile care minimiza pierderea de

căldură.

• se bazează în principal pe ventilație naturală de vara de răcire.

Înţelegerea aceste principii de bază ale seră solare proiect vă va asista în proiectarea, construcţia şi

întreţinerea o structură eficiente energetic. De asemenea, puteţi utiliza aceste concepte care vă ajută

să căutaţi informaţii suplimentare, fie de pe "Web," în jurnale sau în cărţi la librăriile şi biblioteci.

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Solare cu efect de seră Designs

Ataşat sere solare sunt lean-to structuri care formează o cameră jutting de la o casă sau hambar.

Aceste structuri spațiu pentru transplanturile, ierburi sau cantități limitate de hrană. Aceste structuri

de obicei au un design pasivă solare.

Tancuri serele solare sunt suficient de mare pentru producția comercială de culturi, legume sau plante

aromatice. Există două primar desene sau modele pentru serele solare tancuri: tipul de magazie și

hoophouse. Un tip de magazie solare seră este orientată spre are axa lungă să fie difuzate de la est la

vest. Peretele de Sud-confruntă este lustruit să colecteze valoarea optimă a energiei solare, în timp ce

wall nord-cu care se confruntă este well-insulated pentru a preveni pierderea de căldură. Această

orientare este în contrast cu o seră convenţionale, care are său acoperiş execută Nord-Sud pentru a

permite distribuția luminii uniforme pe toate laturile de plante. Pentru a reduce efectele săraci

distribuția luminii într-o seră orientate spre est-vest, peretele nord este acoperit sau pictat cu

reflectorizant.(2)

Tancuri magazie de tip solare sere(2)

Pentru ierni reci, latitudinile medii ale emisferei nordice, și utilizarea tot parcursul anului:

• Nord de abrupt acoperiş avânt la unghiul de soarele de vară cea mai mare de reflecţie de lumină întregul maximă pe plante;• Zidul de Nord verticale pentru stashing de căldură de stocare.• 40-60 ° înclinat acoperiş Sud geam.• verticală kneewall suficient de mare pentru a se potrivi plantare paturi si zapada alunece de pe acoperiş.• sfârşitul pereți parțial lustruit pentru lumina adăugată.• Acoladă Institutul de proiectare continuă Nord acoperiş pantă în jos la sol (eliminarea zidul de Nord), care să permită mai multe zona plantare în pământ, dar nici un depozit de căldură de perete de Nord.

Pentru ierni reci, Mijlociu latitudini U.S. şi year-round utilizaţi (similar cu proiectarea popularizat de Institutul de tehnologie interne, consultaţi resurse pentru planurile şi adresa):

• 45-60 ° Nord acoperiş panta.• Zidul de Nord verticală pentru depozitarea suprapunere de căldură.• 45 ° Sud acoperiş geam.• verticală kneewall.• parte din ziduri de sfârşitul lustruit pentru lumina suplimentare.

Iernile sunt atenuate, sudul U.S. latitudini și utilizarea tot parcursul anului, în care mai puţin de căldură de stocare este necesar:

• 45-70 ° Nord acoperiş panta — acoperiş panta steeper și zidul de Nord mai scurte, mai puţin spaţiu este necesară pentru stivuirea termice de stocare.• acoperiş poate extinde în jos la pământ, eliminarea kneewall înapoi în cazul în care depozitarea nu este utilizarea.• 20-40 ° Sud acoperiş geam.• față kneewall fel de mare ca este nevoie de acces la paturi in fata.• majoritatea sfârşitul pereţi lustruit pentru lumina suplimentare.

Hoophouses tancuri sunt structuri simetrice, rotunjite. Spre deosebire de tipul de magazie solare sere,

acestea nu au o partea de Nord izolate. Solarizare aceste structuri implică practici care îmbunătăţesc

absorbție și distribuție a energiei termice solare introducerea ei. Acest lucru implică de obicei colecţie

de căldură solare în sol sub podea, într-un proces numit pământ termice stocare (ETS), precum și în

alte materiale de stocare, cum ar fi apă sau roci dislocate. Izolare a peretelui cu efect de seră este

important pentru minimizarea pierderii de căldură. Sisteme de absorbție de căldură și metodele de

izolare sunt discutate în detaliu în următoarele secţiuni.

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Solare de absorbție de energie termică

Doi factori cele mai critice care afectează cantitatea de căldură solare o seră este capabil să absoarbă

sunt:

• Poziţia sau locaţia cu efect de seră în raport cu soarele

• Tipul de geam materialul utilizat

Orientarea solare

Deoarece energie de la soare este mai puternică pe latura de Sud a unei clădiri, geamuri pentru serele

solare ideal ar trebui să se confruntă Sud adevărat. Cu toate acestea, în cazul în care copaci, Munţii

sau alte clădiri bloca calea soarelui atunci când seră este într-o orientare Sud adevărat, o orientare în

termen de 15 ° la 20 ° de Sud adevărat va oferi aproximativ 90% din captură solare de o orientare Sud

adevărat. Latitudine de locaţia și locația potenţiale obstacole pot solicita, de asemenea, că vă ajusta

orientarea dumneavoastră cu efect de seră uşor la south adevărat pentru a obţine câştig optimă de

energie solară.(2) Cultivatorii de unele recomanda orientare de seră oarecum la sud-est pentru a

obţine cel mai bun câştig solare în primăvara, mai ales dacă seră este utilizată în principal să crească

transplanturi.(3) Pentru a determina orientarea corectă pentru clădiri solare în zona dumneavoastră,

vizitează programul de diagramă soare la laboratorul de monitorizare Universitatea din Oregon solare

radiații pagina Web. Trebuie să ştiţi dumneavoastră latitudine, longitudine şi fusul orar pentru a utiliza

acest program.

Calea solare la 40 ° latitudine nordică (2)

Panta Material pentru geamurile

În plus faţă de orientare nord-sud, cu efect de seră geamuri trebuie să fie corect înclinat să absoarbă

cea mai mare cantitate de căldură de la soare. Un bun empiric este pentru a adăuga 10 ° sau 15 °

latitudine site-ul pentru a obţine unghiul de buna. De exemplu, dacă sunteţi în California de Nord sau

Illinois centrală la 40 ° Nord latitudine, geamul trebuie să fie înclinat la unui 50 ° de unghiul de 55 ° (40

° + 10 ° sau 15 °).(4)

Geamuri

Materialele folosite în sere solare geamurile ar trebui să permită cea mai mare cantitate de energie

solară să intre în de seră, în timp ce minimizarea pierderii de energie. În plus, creșterea plantei bun

presupune că materialele pentru geamurile permite un spectru naturale de radiaţii photosynthetically

activă (PAR) pentru a intra. Stare brută-suprafață sticlă, dublu strat rigide din material plastic şi

fiberglass lumină difuză, în timp ce clar sticlă transmite lumina directă. Deşi plantele cresc bine cu

lumină directă şi difuze, lumină direct prin geamurile subdivizate după sprijină structurale cauze mai

multe umbre şi creșterii plantelor inegala. Lumină difuză care trece prin geamurile evens afară umbre

cauzate de susţine structurale, care rezultă în mai multe chiar creșterii plantelor.(5, 6)

Multe noi cu efect de seră materialele pentru geamurile au apărut în ultimele decenii. Materiale

plastice acum sunt dominante tip de geam utilizate în sere, cu weatherability aceste materiale fiind

îmbunătăţită prin radiaţii ultraviolete degradare inhibitori, radiații infraroşu (IR) de atenuare a

șocurilor, picurare anti-condensation suprafețelor și radiația unic transmiterea proprietăţi.(7)

Metoda utilizată pentru montarea material geamurile afectează suma de pierdere a căldurii.(8), De

exemplu, crăpături sau găuri cauzate de montare va permite căldură să scape, în timp ce diferențele

de lățimea spațiului aerian între două smalțuri va afecta retenţie de căldură. Instalare şi schelet pentru

anumite materiale de geamuri, cum ar fi acrylics, trebuie să țină seama de extinderea și contracția cu

cald si rece vremea lor.(7) Ca regulă generală, o seră solare ar trebui să aibă de aproximativ 0,75 la

1,5 metri pătraţi de geamuri pentru fiecare pătrat picior de podea spaţiu.(1)

Tabelul 1. Caracteristicile de geamuri

Sticlă — singur stratLumina transmiterea *: 85-90%Bolizi **: 0.9

Avantajele:• Durată nedeterminată dacă nu rupt• Temperat sticlă este mai puternic şi necesită mai puţine suport baruri

Dezavantaje:• Fragile, uşor rupt• Nu poate rezista la greutatea de zăpadă• Necesită numeroase sprijină• Clar sticlă difuze lumină

Fabrică sigilate sticlă dublăLumina transmiterea *: 70-75%Bolizi **: dublu strat 1.5-2.0, low-e 2.5

Avantajele:• Durată nedeterminată dacă nu rupt• Pot fi utilizate în zonele cu temperaturilor de îngheț

Dezavantaje:• Grele• Clar sticlă difuze lumină• Dificil pentru a instala, necesită definirea precisă

Polietilenă — singur stratLumina transmiterea *: 80-90%-material nouBolizi **: singur filmul 0.87

Avantajele:• IR filme au tratament pentru a reduce pierderea de căldură• Nu picătură filme sunt tratate pentru a rezista condensare• Tratament cu acetat de vinil etil rezultate în rezistența la cracare la rece şi de rupere• Uşor de instalat, precise nu judicioase necesare• Material geamurile de costul mai mic

Dezavantaje:• Uşor rupt• Nu poate vedea prin• Polietilenă rezistentă la UV dureaza numai 1-2 ani• Scade de transmisie a luminii în timp• Extinderea şi sag în vremea calda, apoi micşora în vreme rece

Polietilenă — strat dubluLumina transmiterea *: 60-80%Bolizi ** dublu filme: 5 ml filmul 1.5, 6 ml filmul 1.7

Avantajele:• Pierderea de căldură redusă semnificativ atunci când se utilizează un ventilator pentru a oferi un spaţiu aerian între două straturi• IR filme au tratament pentru a reduce pierderea de căldură• Nu picătură filme sunt tratate pentru a rezista condensare• Tratament cu acetat de vinil etil rezultate în rezistența la cracare la rece la rupere• Uşor de instalat, precise nu judicioase necesare• Cel mai mic cost material de geamuri

Dezavantaje:• Uşor rupt• Nu poate vedea prin• Polietilenă rezistentă la UV dureaza numai 1-2 ani• Scade de transmisie a luminii în timp

• Extinderea şi sag în vremea calda, apoi micşora în vreme rece

Polietilenă — cartonului ondulat densitate mareLumina transmiterea *: 70-75%Bolizi **: 2.5-3.0

Avantajele:• Mucegai, chimice și rezistente la apă• Nu galben

Dezavantaje:n/a

Stratificată acrilic/poliester filmul — strat dubluLumina transmiterea *: 87%Bolizi **: 180 %

Avantajele:• Combină weatherability de acrilic cu temperaturi ridicate ale serviciilor de poliester• Poate dura 10 ani sau mai mult

Dezavantaje:• Arcrylic sticlă extinde şi contract considerabil; încadrare are nevoie pentru a permite această schimbare în mărimea• Nu rezistente la foc

Impactul modificate acrilic — strat dubluLumina transmiterea *: 85%

Avantajele:• Nu degradate sau decolorate în lumină UV• Forţa de impact ridicat, bun pentru locaţii cu grindină

Dezavantaje:• Arcrylic sticlă extinde şi contract considerabil; încadrare are nevoie pentru a permite această schimbare în mărimea• Rezistente nu la foc

Fibra întărite de plastic (FRP)Lumina transmiterea *: 85-90%-material nouBolizi **: singur strat 0.83

Avantajele:• Natura translucide acest material diffuses şi distribuie uniform lumină• Tratate de Tedlar panouri sunt rezistente la vremea, lumina soarelui şi acizi• Puteţi ultimii 5-20 ani

Dezavantaje:• Scade de transmisie a luminii în timp• Rezistenţă săraci de la vremea• Cel mai inflamabile materialele vitrajelor rigide• Abilitatea de izolare nu produce zăpadă pentru a topi

Policarbonat — dublu perete rigide din material plasticLumina transmiterea *: 83%Bolizi **: 6 mm 1.6, 1.7 de 8 mm

Avantajele:• Cele mai rezistente la foc de plastic materialele vitrajelor• Rezistentă la UV

Policarbonat filmul — triplu şi quad perete rigide din material plasticLumina transmiterea *: 75%Bolizi ** triplu pereţi: 8 mm 2.0-2.1, 16 mm 2.5Bolizi ** quad perete: 6 mm 1.8, 8 mm 2.1

Avantajele:• Cele mai rezistente la foc de plastic materialele vitrajelor

• Foarte puternic• Uşoare• Uşor de tăiat şi a instala• Oferă performanţă bună pentru 7-10 ani

Dezavantaje:• Pot fi scumpe• Nu clar, translucide

• Rezistentă la UV• Foarte puternic• Uşoare• Uşor de tăiat şi a instala• Oferă performanţă bună pentru 7-10 ani

Dezavantaje:• Pot fi scumpe• Nu clar, translucide

Surse: (2, 6, 7, 13, 14)* Notă că schelet scade cantitatea de lumină care pot trece printr- şi fi disponibil ca energie solară ** Bolizi este o măsură de comune de izolare (hr°Fsq.ft/BTU)

Aveţi nevoie pentru a înţelege patru numere în selectarea geamuri pentru serele solare. Două numere descrie randamentul termic a geamului, şi alte două numere sunt importante pentru creșterea plantei productiv. Materialele pentru geamurile multe includ un autocolant de Consiliul Naţional de evaluare a Fenestration, care listează următorii factori:

• SHGC sau energie termică solară obţine coeficientul este o măsură a cantității prezente de lumină solară care trece printr-un geam de material. Un număr de 0,60 sau mai mare este de dorit.

• Factorul de u este o măsură de căldură care este pierdut în afara printr-un geam de material. Un număr mai mare sau egală cu 0.39 BTU/hr-ft2-F este de dorit.

• VT sau vizibil factor de transmisie se referă la cantitatea de lumină vizibilă care introduce printr-un geam de material. Un număr de 0.70 sau mai mare este de dorit.

• PAR sau radiații photosynthetically activă este cantitatea de lumina soarelui în lungimi de undă critice pentru fotosinteză şi creşterea plante sănătoase. Gama de lungime de undă PAR este între 400-700 Nano-metri (o măsură de lungime de undă).

Notă: Când alegerea geamuri, uita la transmisia vizual totală, nu PAR transmisia, pentru a vedea dacă materialul permite spectru de lumină necesare pentru creșterea plantei sănătos.

În plus faţă de eficienţei energetice și transmisie a luminii, ar trebui să luaţi următoarele atunci când alegeţi materialele pentru dumneavoastră cu efect de seră geamurile:

• Durată de viaţă• Rezistenţă la deteriorări cauzate de grindină și pietre• Abilitatea de a sprijini snowload• Rezistenţă la condensare• Foaie dimensiunea și distanța necesar între sprijină• Rezistenţă la foc• Ușor de instalat

(Bazat pe 6, 9, 10, 11, 12, 13, 14)

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Solare de stocare de căldură

Pentru serele solare pentru a rămâne cald în timpul nopţi rece sau zilele tulbure, căldura solară care

introduce pe zile insorite trebuie depozitate în seră pentru o utilizare ulterioară. Metoda cea mai

comună pentru stocarea energiei solare este să plasaţi roci, beton, sau apă în linie directă cu lumina

soarelui să absoarbă sale de căldură.(1)

Cărămidă sau pereții umplute cu beton cinder bloc la partea din spate (partea de Nord) de seră poate

oferi, de asemenea, depozitare de căldură. Cu toate acestea, numai exterioară patru centimetri de

grosime de acest material de stocare efectiv absoarbe energie termică. Mediu şi întuneric colorate

dale ceramice pardoseală poate oferi, de asemenea, unele stocare de căldură.Pereţi (15) nu sunt

utilizate de absorbție de energie termică trebuie lumina colorate sau reflectorizant de căldură directe

și lumina înapoi în seră și pentru a asigura o distribuție mai chiar a luminii plantelor.

Materiale de stocare

Cantitatea de material de stocare de căldură necesare depinde de locaţia dumneavoastră. Dacă locuiţi

în sudul sau mid-latitude locuri, veţi avea nevoie de cel puțin 2 galoane de apă sau în 80 de livre de

roci pentru a stoca căldura transmisă prin fiecare pătrat picior de geam.(16) În cazul în care locuiţi în

statele nordice, veti avea nevoie 5 galoane sau mai mult de apă pentru a absorbi termic care intră prin

fiecare pătrat picior de geam.(1) Aproximativ trei de metri pătraţi de patru-inch gros cărămidă sau bloc

cinder perete este necesar pentru fiecare pătrat picior de Sud-confruntă sticlă.(15)

Cantitatea de material de căldură de stocare necesar, de asemenea, depinde dacă intenţionaţi să

utilizaţi dumneavoastră cu efect de seră solare pentru extinderea perioadei de vegetație, sau dacă

doriţi să crească year-round plante în el. Pentru sezonul extensie în rece climate, veti avea nevoie 2 ½

galoane de apă pe picior patrat vitrajelor, sau aproximativ jumătate din ceea ce ar fi nevoie pentru

producția tot parcursul anului.(2)

Dacă utilizaţi apă ca material de căldură de stocare, obişnuiţi galon 55 tobe pictat o culoare întuneric,

reflectorizant de lucru bine. Containere mai mici, cum ar fi lapte căni sau sticle din sticlă, sunt mult

mai eficient decât galon 55 tobe în furnizarea de stocare de căldură în zone care sunt frecvent tulbure.

Recipient mai mici are o proporţie mai mare din suprafața care rezultă în mai rapidă absorbția căldurii,

atunci când soarele straluceasca.(14) Din păcate, recipientele din material plastic se degradează după

două sau trei ani în lumina directă a soarelui. Recipiente de sticlă clar oferi avantaje de capturare

căldură mai bine decât întuneric recipientele din metal şi nu degradant, dar ele pot fi uşor de spart.

(17)

Trombe peretii sunt o metodă inovatoare pentru absorbția căldurii și depozitare. Acestea sunt scăzută

pereţi plasat în interiorul seră lângă Sud-confruntă windows. Ei absorbi energie termică pe partea din

față (orientat spre sud) de perete şi apoi radia acest căldură în seră prin partea de spate (orientate

spre nord) de perete. Un perete de Trombe constă într-un perete de 8-16 inch gros zidărie acoperit cu

un material întunecat, absorbţiei de căldură şi cu care se confruntă cu un singur sau dublu strat de

sticlă plasate la 3/4 "6" departe de perete de zidărie pentru crearea unui spațiu aerian mici. Termică

solară trece prin sticlă și este absorbită de suprafață întunecată. Această energie termică este stocată

în perete, în cazul în care se efectuează încet perfecţionare activă prin intermediul zidărie. Dacă

aplicaţi o foaie de folie metalică sau alte suprafeței de reflexie pe suprafața exterioară a peretelui,

aveţi posibilitatea să măriţi termice solare absorbție de 30-60% (în funcţie de climă) în timp ce

descrescătoare potențial de pierdere de căldură prin pasivă radiații.(10, 18)

Trombe perete.Foto: Australian Centrul pentru energie regenerabilă

Apă peretii sunt o variație de perete Trombe. În loc de un zid de zidărie, umplut cu apă containere sunt

plasate în conformitate cu razele solare între partea de sticlă şi spaţiu de lucru cu efect de seră. Apa

poate fi în tuburi hard, din plastic sau alte recipiente voinic şi partea de sus a peretelui poate servi ca

un banc. Peretele de apă Solviva solare cu efect de seră constă din două 2 x 4 cai pereţi, cu știfturi

introduse două picioare pe centru. Un unul-picior spaţiere se conectează două ziduri. Acoperite cu

material plastic cal gard sârmă apoi a fost atașează fiecărui perete de stud şi pungi de apă de plastic

grele, întuneric colorate au fost inserate în spațiul dintre două ziduri. Pereţi de cai au fost poziționați

vertical în conformitate cu razele solare înainte de a saci fiind umplut cu apă.(19) Ambele Solviva și

Trei surori fermă pagini Web furnizează desene sau modele pentru construcţia solare sere, folosind

apă pereţi.

Utilizaţi roci în loc de apă pentru depozitarea de căldură. Roci ar trebui ½ la jumătate de centimetri în

diametru pentru a oferi mare suprafață de absorbție de energie termică.(5) Ele pot scămos în cuşti de

plasă de sârmă pentru a le conținute menţine. Deoarece pietre au o mult BTU stocare valoare mai

mică decât apa (BTU/sq.ft/°F 35 de roci faţă de 63 pentru apă) (13), veţi avea nevoie de trei ori

volumul de roci pentru a oferi aceeaşi sumă de stocare de căldură. Pietre au, de asemenea, mai multe

rezistență la aer fluxul decât apa, care rezultă din transferul de căldură mai puţin eficientă.(20)

Oricare dintre materialul alegeţi să utilizaţi pentru stocare de căldură, acesta ar trebui introduse în

cazul în care acesta va colecta şi absorbi mai căldură, în timp ce pierde puţin de căldură aer

înconjurătoare. Nu plasaţi termice masă astfel încât atinge orice pereți exteriori sau geamuri, deoarece

acest lucru rapid va atrage căldură departe.

Faza de schimbare

În loc de apă sau roci pentru depozitarea de căldură, se poate utiliza faza-modificarea materialelor. În

timp ce faza-schimba materiale sunt de obicei mai scumpe decât materii prime convenționale, ele sunt

5 până la 14 ori mai eficient în stocarea căldură decât apă sau roci dislocate. Astfel, ei sunt utile când

spaţiul este limitat. Materiale de schimbare pe faza includ:

• ortofosfat dodecahidrat

• thiosulfate de sodiu pentahidrat

• parafină

• Glauber's sare (dcahydrate de sulfat de sodiu)

• clorură de calciu hexahidratată şi

• acizi grași (21, 22)

Ei absorbi şi stoca căldură când modificaţi din solide în faza lichidă şi apoi eliberaţi acest căldură,

atunci când le schimba înapoi în faza solidă.(5) Clorură de calciu hexahidratată are o căldură stocarea

capacitate de 10 ori de apă.(23) Aceste materiale sunt, de obicei, conținute în tuburi etanșe, cu mai

multe tuburi poate cere să furnizeze suficiente de stocare de căldură. Din cauza capacitatea faza-

schimba materiale să absoarbă mari cantități de căldură, de asemenea, sunt utile în moderarea

temperaturi cu efect de seră în vara.

Cele mai multe de cercetare cu privire la utilizarea materialelor faza-schimba pentru serele s a

efectuat în Europa, Israel, Japonia și Australia. În Israel, faza-schimba materiale au fost încorporate în

seră geamurilor, care a crescut căldură capturarea și reținerea, dar a redus transparenţă geamuri pe

tulbure zile când materialul de schimbare fază nu a devenit lichid.(24) În momentul publicării, au fost

identificate două societăți — unul în SUA şi altul în Australia — care vinde sisteme de încălzire

underfloor folosind materiale de schimbare de fază.(25, 26) Faza-schimbare drywall, în prezent în

cercetare, încorporează materiale faza schimbare în interiorul wallboard comune pentru a creşte

capacitatea de stocare căldură şi ar putea înlocui mai grele, mai scumpe, convenţionale termice mase

utilizate în încălzirea localurilor pasivă solare.(27) A se vedea referința secţiune pentru o listă de

publicaţii şi site-uri Web care oferă informații suplimentare despre faza schimba materiale.

Pentru mai multe informaţii, consultaţi site-ul Web Faza schimbare energie termică stocare oferă o

discuţie detaliată a acestei tehnologii.

Pentru mai multe case, construirea o seră solare ataşat este foarte atrăgătoare. Ei cred că le poate extinde lor gradina de vegetație în timp ce reducerea lor de origine facturile de încălzire. Din păcate, există o contradicţie între utilizarea o seră să crească plante și utilizarea de ea ca un colector solare pentru încălzire casa.(9, 28)

• Pentru a furniza căldură pentru un casă, un solare colector trebuie să fie capabil de a colecta căldură în exces faţă de ceea ce poate tolera plante.

• Mult de căldură care intră într-o seră este utilizată pentru evaporarea apei din sol și din plante frunze, care rezultă în stocare pic de energie termică pentru import definitiv.

• Un colector de acasă de căldură trebuie sigilate să minimizaţi de pierdere a căldurii. Sere; cu toate acestea, necesită unele ventilație pentru a păstra nivelele specifice de dioxid de carbon pentru plante respiraţie şi pentru a preveni acumulării de umiditate că favoruri plante boli.

Bioshelters oferă o excepție de la această regulă. În bioshelters, seră producătoare de alimente nu este un "supliment", la casa,

dar este o parte integrantă a spaţii de locuit. Bioshelters adesea integra pește sau animale mici cu productia vegetala la nutritiv cicluri complete. Măsurile de control biologic și diversitatea de plante sunt folosite pentru a gestiona dăunători într-un mod care este sigur pentru oameni şi pets în cabinele de locuit. În primul rând pioneered de Nou Alchemy Institutul de Est Falmouth, Massachusetts, în anii 1970, Solviva și Trei surori fermă desfășura tradiţie bioshelter.

Active Solar

An active method for solar heating greenhouses uses subterranean heating or earth thermal storage

solar heating. This method involves forcing solar-heated air, water, or phase-change materials through

pipes buried in the floor. If you use hot air for subsurface heating, inexpensive flexible drainage or

sewage piping about 10 centimeters (4 inches) in diameter can be used for the piping. Although more

expensive, corrugated drainage tubing provides more effective heating than smooth tubing, since it

allows for greater interaction between the heat in the tube and the ground. The surface area of the

piping should be equal to the surface area of the floor of the greenhouse. You can roughly calculate

the number of feet of four-inch tubing you will need by dividing the square feet of greenhouse floor

area by two. Once installed, these pipes should be covered with a porous flooring material that allows

for water to enter into the soil around them, since moist soil conducts heat more effectively than dry

soil. The system works by drawing hot air collected in the peak of the roof down through pipes and into

the buried tubing. The hot air in the tubes warms the soil during the day. At night, cool air from the

greenhouse is pumped through the same tubing, causing the warm soil to heat this air, which then

heats the greenhouse.(29, 30) For more information on this design, see Solar Greenhouses for

Commercial Growers (29), or visit the Web page of Going Concerns Unlimited, a solar energy company

in Colorado.

Root-zone thermal heating with water is normally used in conjunction with gas-fired water heaters.

This system can be readily adapted to solar and works well with both floor or bench heat. Bench-top

heating with root-zone thermal tubing is widely practiced in modern greenhouse production and can

be installed easily. A permanent floor heating system consists of a series of parallel PVC pipes

embedded on 12" to 16" centers in porous concrete, gravel, or sand. Water is heated in an external

solar water heater then pumped into the greenhouse and circulated through the pipes, warming the

greenhouse floor. Containerized plants sitting directly on the greenhouse floor receive root-zone heat.

Additional information on root zone heating can be found in the ATTRA publication Root Zone Heating

for Greenhouse Crops.

The Solviva greenhouse uses a variation of active solar heating. The system in this greenhouse relies

on heat absorption by a coil of black polybutylene pipe set inside the peak of the greenhouse. The pipe

coil lays on a black background and is exposed to the sun through the glazing. A pump moves water

from a water tank, located on the floor of the greenhouse, to the coiled pipe, and back to the tank.

Water heated within the coils is capable of heating the water in the tank from 55°F to 100°F on a

sunny day. The heat contained in the water tank helps keep the greenhouse warm at night.(19)

Greenhouse management practices also can affect heat storage. For example, a full greenhouse

stores heat better than an empty one. However, almost half of the solar energy is used to evaporate

water from leaf and soil surfaces and cannot be stored for future use.(5, 31) Solar heat can be

complemented with heat from compost as described in the ATTRA publication Compost Heated

Greenhouses. Besides adding some heat to the greenhouse, increased carbon dioxide in the

greenhouse atmosphere, coming from the decomposition activities of the microorganisms in the

compost, can increase the efficiency of plant production.

While solar greenhouses can extend your growing season by providing relatively warm conditions, you should carefully select the types of plants that you intend to grow, unless you are willing to provide backup heating and lighting.

Vegetables and herbs that are suitable for production in a winter solar greenhouse include:

Cool temperature tolerant: Basil, celery, dill, fennel, kale, leaf lettuce, marjoram, mustard greens, oregano, parsley, spinach, Swiss chard, turnips, cabbage, collards, garlic, green onions, and leeks.

Require warmer temperatures: Cherry tomatoes, large tomatoes, cucumbers (European type), broccoli, edible pod peas, eggplant, and peppers.

(Based on 28)

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Insulation

Wall and Floor Insulation

Good insulation helps to retain the solar energy absorbed by thermal mass materials. Keeping heat in

requires you to insulate all areas of the greenhouse that are not glazed or used for heat absorption.

Seal doors and vents with weather stripping. Install glazing snugly within casements. Polyurethane

foams, polystyrene foams, and fiberglass batts are all good insulating materials. But these materials

need to be kept dry to function effectively. A vapor barrier of heavy-duty polyethylene film placed

between the greenhouse walls and the insulation will keep your greenhouse well insulated.(1)

Unglazed areas should be insulated to specifications of your region. For example, R-19 insulation is

specified for greenhouses in Illinois (1) and in Missouri (24), while R-21 is recommended for walls in

New Mexico.(10) The ZIP-Code Insulation Program Web site provides a free calculator for finding

recommended insulation R-values for houses based on your zip code.

Richard Nelson of SOLAROOF developed an innovative way to insulate greenhouse walls in a

hoophouse-style greenhouse. This system involves constructing a greenhouse with a double layer of

plastic sheeting as glazing. Bubble machines (such as are used to create bubbles at parties) are

installed in the peak of the greenhouse between the two layers of plastic. At least two generators

should be installed, at either end of the greenhouse. During the winter, the bubble machines face

north and blow bubbles into space between two sheets of plastic on the north side of the greenhouse

to provide R-20 or higher insulation for northern winters. During the summer, the bubble machines can

be turned to face south to provide shading against high heat.(33)

Bubble greenhouse design.

On greenhouse floors, brick, masonry, or flagstone serves as a good heat sink. However, they can

quickly lose heat to the ground if there is not an insulating barrier between the flooring and the soil. To

protect against heat loss, insulate footings and the foundation with 1- to 2-inch sheets of rigid

insulation or with a 4-inch-wide trench filled with pumice stone that extends to the bottom of the

footings. You also can insulate flooring with four inches of pumice rock. Besides insulating the floor,

this method also allows water to drain through. (16)

External Insulation

You also can insulate your greenhouse by burying part of the base in the ground or building it into the

side of a south-facing hill.(5) Straw bales or similar insulating material also can be placed along the

unglazed outside walls to reduce heat loss from the greenhouse.(34) Underground or bermed

greenhouses provide excellent insulation against both cold winter weather and the heat of summer.

They also provide good protection against windy conditions.(35) Potential problems with an

underground greenhouse are wet conditions from the water table seeping through the soil on the floor

and the entry of surface water through gaps in the walls at the ground level. To minimize the risk of

water rising through the floor, build the underground greenhouse in an area where the bottom is at

least five feet above the water table. To prevent water from entering the greenhouse from the outside,

dig drainage ditches around the greenhouse to direct water away from the walls. Also, seal the walls

with waterproof material such as plastic or a fine clay. An excellent description of how to build a simple

pit greenhouse is provided at the Web page for the Benson Institute, a division of the College of

Biology and Agriculture at Brigham Young University (BYU). This Institute has a campus in Bolivia

where students built an underground greenhouse based on local, traditional practices.(36)

The Walipini greenhouse, a traditional underground greenhouse from Bolivia.(36)

Glazing is what allows light and heat into a solar greenhouse. It can also be the greatest area for heat

loss. As mentioned previously, increasing the insulating value of glazing often decreases the amount of

sunlight entering the greenhouse. When selecting glazing for your greenhouse, look for materials that

provide both good light transmission and insulating value. For example, polyethylene films referred to

as "IR films" or "thermal films" have an additive that helps reduce heat loss.(37) Double or triple

glazing provides better insulation than single glazing. Some greenhouse growers apply an extra layer

of glazing—usually a type of film—to the interior of their greenhouses in winter to provide an extra

degree of insulation. Adding a single or double layer of polyethylene film over a glass house can

reduce heat loss by as much as 50%.(38) By using two layers of polyethylene film in plastic-film

greenhouses with a small fan blowing air between them to provide an insulating air layer, heat losses

can be reduced by 40% or more, as compared to a single layer of plastic.(39)

Greenhouse curtains limit the amount of heat lost through greenhouse glazing during the night and

on cloudy days. By installing greenhouse insulation sheets made from two-inch thick bats of

polystyrene, you can reduce by almost 90% the heat that would otherwise be lost through the glazing.

For a small greenhouse where labor is not a large constraint, you can manually install the polystyrene

sheets at night and remove them in the morning. Magnetic clips or Velcro fasteners will facilitate the

installation.(1) Alternatively, you can install thermal blankets made of polyethylene film, foam-backed

fiberglass, or foil-faced polyethylene bubble material. These blankets are supported on wire tracks and

can be raised or lowered using pulleys. While greenhouse curtains composed of thermal blankets are

usually opened and closed manually, a few manufactures have motorized roll-up systems that store

the blanket near the greenhouse peak.(5)

Solar greenhouse with solar curtains, water wall, and water heat storage on the north wall.(2)

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Ventilation

A building designed to collect heat when temperatures are cold also needs to be able to vent heat

when temperatures are warm. Air exchange also is critical in providing plants with adequate levels of

carbon dioxide and controlling humidity. Because of the concentrated air use by plants, greenhouses

require approximately two air exchanges per minute (in contrast to the one-half air exchange per

minute recommended for homes). To determine the flow requirements for your greenhouse, multiply

the volume of the greenhouse by two to get cubic feet of air exchange per minute, which is the rate

used in determining the capacity of commercial evaporative coolers.

Roof-ridge and sidewall vents provide natural ventilation. The sidewall vents allow cool air to flow into

the sides of the greenhouse, while ridge vents allow the rising hot air to escape. Some wind is

necessary for this type of ventilation system to function effectively. On still, windless days, fans are

necessary to move air through the greenhouse. The area of the venting should be equal to between

1/5 to 1/6 of the greenhouse floor area.(1)

Solar chimneys are

passive solar collectors

attached to the highest

point on the greenhouse

and are combined with

vents or openings on

either end of the

greenhouse. The

chimney has an inlet that

draws warm air from

inside the greenhouse

and an outlet that

discharges it to the

outdoors. To enhance

solar gain inside the

chimney and increase

airflow, the inner surface

of the chimney stack is glazed or painted black. A ventilator turbine added to the top of the chimney

provides an additional force to pull warm air up from inside the greenhouse.(40)

Thermal storage materials are effective in keeping a greenhouse cool in summer as well as keeping it

warm in winter. Since these materials absorb heat during the day, less heat radiates within the

greenhouse when the sun is shining. When the sun goes down, heat released from the thermal storage

materials can be vented out of the greenhouse.(2)

Removing external shading can also decrease heat build-up within the greenhouse. Shading provided

by mature trees is not recommended. Older books on solar greenhouse design (e.g., 2) argue that

deciduous trees can provide shade in the summer but allow for plenty of sunlight to enter through the

glazing in the winter after the leaves are gone. However, more recent literature notes that a mature,

well-formed deciduous tree will screen more than 40% of the winter sunlight passing through its

branches, even when it has no leaves.(31)

Active solar cooling systems include solar air-conditioning units and photovoltaics set up to run

standard evaporative cooling pads. Both are more complex and expensive to equip than passive

systems.

Putting It All Together

Designing and building a solar greenhouse can be an exciting and rewarding project. Feel free to rely

on the older literature to provide you with basic siting, design, and construction guidelines. However,

incorporating new glazing, heat storage, and insulating materials into your design can greatly enhance

the efficiency of your structure. Several consulting companies can provide you with blueprints and

A solar chimney. (2)

design assistance, often at a reasonable cost. See the Resources section for names and contact

information for these companies. Of course, you need to weigh the costs of these new technologies

against the value of your greenhouse-grown crops. As you become familiar with the principles of

passive solar design, you may want to experiment with ways of harnessing the power of the sun within

your greenhouse to produce better plants throughout the year.

Solar Rooms -- from Passive Solar Energy Book This is the section of the book Passive Solar Energy by Bruce Anderson and Malcolm Wells that deals with solar rooms, sunspaces and greenhouses. It includes solar room ideas and design information, as well as construction drawings and some example photos of solar rooms. This material is made available through the generosity of the authors. The entire book, covering many aspects of passive solar energy can be downloaded here.

Without ventilation or thermal mass, the temperatures of spaces having large areas of south-facing windows will fluctuate widely. Temperatures of conventional non-solar greenhouses, for example, can rise to over 100° on sunny winter days and then drop to below freezing at night. If a sun heated room is permitted to have wider-than-normal temperature fluctuation, then the costs of thermal mass (to store heat) and movable insulation (to reduce heat loss) are avoided. The excess warmth from such a "solar room" can heat the house immediately, or if mass is added, heat can be stored for later use after the sun sets. Almost always, the solar room is warmer than the outdoor temperature, thus reducing heat loss from the building where the room is attached. Examples of solar rooms include greenhouses, solariums, and sun porches. Greenhouses are the most common solar rooms. Conventional greenhouses, however, are not designed to take maximum advantage of the sun's energy. The problem is that most are built with a single layer of glass, and so they lose more heat at night than they gain from the sun during the day. Consequently, they need expensive auxiliary heat to keep the plants warm.

A solar greenhouse is designed both to maximize solar gain and to minimize heat loss. Usually, only the south facing walls and roof of the solar greenhouses are glazed, while the east and west walls are well-insulated. (Southeast and southwest portions, if any, are also glazed, partly because plants need that low-angle early sunlight.) If at least two layers of glass or plastic are used instead of one, this type of greenhouse will remain above freezing most of the winter in all but the coldest climates of this country. However, for maximum heat savings while growing plants year round, three and even four layers of glass and plastic should be used where winters have more than 5000 degree days. Keep in mind that each additional layer of glazing blocks additional sunlight. Therefore, for the highest possible light transmission, the third and fourth layers must be a very clear film, such as Teflon™ or Tedlar™. Each layer must be sealed tightly to prevent structural damage from possible moisture condensation between glazing.

For maximum sunshine, and for minimum heat loss at night, movable insulation is used in combination with double glazing. This can be tough to do, however. Some of the tricky design and construction problems include storing the insulation out of the way during the day, interfering with plants while moving the insulation, and obtaining tight seals against the glazing when the insulation is closed. Additional considerations include the need for insulation to resist mold, other plant and insect life, and moisture damage.

Glazing for solar rooms should be vertical or sloped no more than 30° from vertical (at least 60° from horizontal). Before you build, however, talk to everyone you can find who has ever used glass in a sloping position, and ask about leaks. If you can find someone who can convince you of a leak proof system, do not let any details escape your attention. Also, read the fine print in the sealants literature. Some silicones are attacked by mildew, many won't stick to wood, and all must be applied only to super clean surfaces.

Which Direction? Solar rooms that face east or west do not work as well for heating as those that face south. The former supply less heat during the winter and may provide much too much in summer. However, an east-facing greenhouse can give morning light, which plants like; it can be a buffer zone to reduce heat loss from the house throughout the rest of the day. If an east-facing solar room seems to be a good solution to either site or building problems, locate spaces such as kitchens on the east side of the house next to or behind the solar room to take advantage of the morning light and heat. Then the living rooms and bedrooms, which can usually remain cool during the day, will become warm in the afternoon from the heat gained fro Heat Storage

As with other passive systems, thermal mass enhances the performance of a solar room. Thermal storage mass moderates temperature swings, provides more stable growing temperatures for plants, and increases overall heating efficiency. The heat-storing capability of the planting beds can be supplemented with 55-gallon drums, plastic jugs, or other containers of water. Two to four gallons of water per square foot of glazing is probably adequate for most solar rooms.

Many of the most successful solar rooms are separated from the house by a heavy wall that stores the heat. The wall, built of concrete, stone, brick, or adobe, conducts heat (slowly) into the house. At the same time, the wall keeps the solar room cooler during the day and warmer at night. Use the design and construction information for solar walls, but eliminate the glazing.

Earth, concrete, or the floors store considerable heat. So do foundation walls if insulated on the outside. Be sure to use insulation with an R-value of at least 12 (3 inches of Styrofoam™). Insulate at least 3 to 4 feet deep and more in deep-frost country. This gives better protection than insulating 2 feet or so horizontally under the floor When solar rooms larger than 200 square feet reach 90°, a fan can be used to circulate the collected heat. Because plants benefit from having warm soil, hot air can be blown horizontally through a 2-foot-deep bed of stones below the greenhouse floor or under raised planting beds. Stone beds can also be built beneath the floor of the house and should not be insulated from it. Then the heat will rise naturally through the stone beds and into the planting bed soil or into the house.

Two cubic feet of ordinary washed stone per square foot of glazing is sufficient. Use a fan capable of moving about 10 cubic feet of air per minute for each square foot of glazing. Potato-sized stones, larger than the usual 3/4 inch to 1 1/2 inch size, will allow freer air movement. Consult with a local mechanical engineer or heating contractor for the best fan and ducting design. (Keep it simple!)

Costs

Solar rooms can be relatively simple to build, yet they can be very expensive if they are of the same quality and durability as the rest of your house. For example, with a few hundred dollars worth of materials, you can build a simple, wood-framed addition to your house to support thin-film plastics. The resulting enclosure will provide considerable heat, especially if it is not used for growing plants. On the other hand, good craftsmanship and quality materials can result in costs of several thousand dollars. In general, solar rooms are most economical when you can use them for more than providing heat and when they are built to a quality that will both enhance the value of your house and appreciate in value as your house does. Solar rooms are often exempt from local property taxes. Check with your local officials. Large Solar RoomsMost of the information in this chapter is applicable for relatively small solar rooms of 100 to 200 square feet. Unless your house is super insulated or in a mild climate, a solar room of this size will provide less than 25 percent of your heat. For big leaky houses, small solar rooms will provide as little as 5 or 10 percent of the heat. Another way of approaching the use of solar rooms to heat your house is to think of them as rather large spaces that are incorporated into, rather than attached onto, your house. There are a number of advantages with this approach:

1. Both the solar room and house will lose less heat. 2. Heat will move easily from the solar room to your house. 3. Natural light can be made to penetrate deep into your house. 4. The solar room can be easily heated by the house if necessary and so is unlikely to freeze. 5. The solar room can be readily used as an expanded living space. 6. You can build your house compactly and the solar room will provide a feeling of large

exterior wall and window area.

Growing Plants; Some things to rememberGrowing Plants; some things to remember An important function of some solar rooms is the growing of food-and flowers. Warm soil and sufficient light are critical for successful plant growth. Remember that the multiple layers of glass or plastic you may need to use will reduce light levels, a crucial issue in climates with below-average sunshine. Circulation of warm air through gravel beds under the soil can raise planting bed temperatures, increasing the growth rate of most plants.

Cold weather plants, such as cabbage, can tolerate cold temperatures, sometimes even mildly-freezing ones. Few house plants can be permitted to freeze, but many can endure rather cool temperatures. On the other hand, some plants, such as orchids, require stable, high temperatures. When warm, stable temperatures are required, the solar room must retain most of its solar heat; little heat should be allowed to move into the house. Three or four layers of glass or plastic (or movable insulation) and plenty of thermal mass are required to trap and contain the heat in cold climates.

Evaporation of water from planting beds and transpiration by the plants causes humidity. Each gallon of water thus vaporized used roughly 8000 Btus, nearly the same amount of energy supplied by 5 square feet of glass on a sunny day. Also, water vaporization reduces peak

temperatures. It may be undesirable to circulate moisture-laden air into the house, unless the house is very dry.

Greenhouse environments are rather complex ecological systems. Unexpected and sometimes undesirable plant and animal growth may proliferate. Indications are that the greater mix of plants and animals, the more likely a natural balance will eventually be reached. To obtain this balance, some owners leave the door of their solar room open to the outside during the warm and mild weather.

New Alchemy Institute, among others, has pioneered work in natural pest control and companion planting as a step toward success¬ful greenhouse management. They have also investigated fish-raising in large "aquariums," which also serve as thermal mass. Human, animal, and/or plant wastes are integrated into the total ecology of many advanced greenhouses, which are sometimes referred to as bioshelters. A more thorough understanding of the many natural cycles that are possible in greenhouses will offer rewards. Photos of Some Example Solar Rooms Here are photos of several different types of solar rooms, including sunspaces, solar porches, and greenhouses. Construction Details for Solar RoomsThis solar greenhouse uses stock size insulated glass patio door unit s the solar aperture. These units are field-mounted in the wood-framed structure which rests on an added foundation wall of poured concrete or block and which is attached to the existing house wall by 2x4 braces and a 2x4ledger strip bolted to the wall. The side wall can be either clapboard or other siding to match the house. In this design, the two-inch beadboard foundation insulation is located on the inside of the foundation wall to make a weatherproof exterior with no additional finishing required. All optional roll-down insulating curtain is included at the sloped glazing. (Construction details, New England SUEDE.)

My Solar GreenhouseThe quick answer to what a True Solar Greenhouse is.....is that it is capable of collecting all

of the energy it needs from sunlight to maintain suitable temperatures for plant survival and growth. But it's not that simple. It also has to be able to store and distribute the excess

heat for those days when the sun does not shine. Here in Prairie Farm, WI (zone 3) the sun has a nasty habit of not shining when it is needed the most in the late Fall and Winter.

I had wanted a greenhouse for many years but could not justify the costs of heating one through the cold months. Here that means at least October through April and probably parts of May and September also. There are plans for solar greenhouses out there on the Internet and there are several books that have been published on the subject. The designs

offered would perform well in zone 5 and up, but I doubted whether they would be sufficient for my climate. They also had limited growing space for their size. After learning

what I could from available sources, I took the plunge and designed my own keeping in mind my needs and wants and also my ability to build it. Big dreams never become reality

if they are beyond your means to accomplish them.

So with plans in hand I went about the task of assembling the materials needed for building it. Costs were about $1,200 at the local lumber yards. They would have been a lot more if I

had not taken advantage of free materials from friends and neighbors. With some help setting rafters and such, the framing was up. Finishing it off took longer than expected.

Particular care must be taken to ensure that there is no air infiltration from the outside or unwanted heat escape from the inside of the greenhouse. Moisture migration into the walls is a very serious problem and must not be allowed, so tape up every seam in the moisture

barrier. You want to have complete control over air and heat flow in and out of the greenhouse. Green treated lumber is a must where glazing meets framework and anywhere

else moisture will be encountered, and if you have any doubts, use green treated lumber exclusively in the construction.

You will notice from the pictures that my greenhouse only has glazing facing south. This is the most common practice with solar greenhouses. It is the most energy efficient way and the plants still receive plenty of sunlight. Most do not have a glazed knee-wall like mine has. In an area with a lot of snowfall this allows for the snow to slide off the roof glazing

and not block sunlight. It also allows for greater height above the planting beds and easier access to them. Not shoveling snow and maximizing the interior space were important to me. I also chose a 45 degree angle for the roof glazing, which is not the theoretically best angle for this location. You want the sun's rays to be nearly perpendicular to the glazing

when the sun is at its lowest, at the start of winter, to maximize heat gain. I have two things to say about that. First, the available sunshine at that time of year in this area is very

limited and you get very little heat gain when the sun is not shining. Secondly, by choosing the 45 degree angle, it allowed me to use standard length lumber with almost no waste.

This cut costs and allowed me to spend more in other areas which more than made up for the theoretical losses.

Now let's talk about insulation. In designing the greenhouse, over sized rafters and studs must be used to accommodate the thickness of the needed R-value of the insulation. I used R-23 in the north facing wall and roof and R-19 in the east and west facing walls. Inside I

used white styrofoam sheets as a good light reflective wall covering and as added insulation, two inch thick on the north facing wall and ceiling and 1 1/2 inch thick on the

walls. In, under, and outside the base of the greenhouse is a buried two inch thick layer of styrofoam to keep frost from getting into the greenhouse. The glazing is double pane on the

lower rows of glass and triple pane on the upper row of glass.

Heat storage is accomplished two ways in the greenhouse. The first way is by water collection and storage. I have a 300 gallon stock tank and five 55 gallon drums in the

greenhouse to store heat. Secondly, and not to be overlooked, a great deal of heat is stored in the planting beds and floor of the greenhouse. The stored heat in the planting beds is a must to keep cold spots from developing near them, and the heat stored in the floor area passively heats the greenhouse when the sun's not shining. The heat stored in the water

tanks is not where it is needed. It is released into the rear of the greenhouse and rises to the peak. To rectify this I use a small fan at the peak of the greenhouse to force the heat back

down and this also eliminates cold spots.

The best location for my greenhouse was some distance from my house and not near power or water. Both of these problems were easy to correct. Water is collected from the roof of

the greenhouse in more than sufficient quantities. To run the needed fan and lighting in the greenhouse, a small solar panel is used to charge a 12 volt car battery and keep things

running. I also now have a micro wind generator set up next to the greenhouse for those days when the sun doesn't cooperate. The control panel was made up of parts I had laying around. It is not very pretty but does the job. The automatic vent is the wax cylinder type

and requires no power to operate.

Like people, greenhouses have their own personalities, and it takes a little time to get to know them. My biggest surprise was that it functioned pretty much the way that I had

planned. It takes care of itself most of the time and if I install an automatic watering system it might not need me at all. Just kidding. It has taken me through two seasons now and

taught me some things along the way. My vision of it being full of plants like some tropical jungle doesn't work. It is too restrictive on the flow of sunlight in the greenhouse. The

plants got plenty of sunlight but the heat storage did not. This lead to overheating of the air in the greenhouse but a drop in the overall heat stored in the greenhouse. This caused

larger temperature swings inside the greenhouse and the loss of some of my tropical plants. They required a higher minimum temperature than the greenhouse maintained this season, but it looks like most of the plantings came through with minimal or no damage to them. It

took me a little while to figure this out because the first season went so well. The plants were smaller then and were not a problem. More pruning and less dense planting will cure

the problem.

The other interesting thing that has happened is that some of the plants in the rear of the greenhouse have switched growing seasons by going dormant or semi-dormant in the

Summer and having their main growth in the Winter. I think this is an unintended result of my design. I knew that there would be less light in the rear of the greenhouse in the

Summer but still plenty of light for proper plant growth. When I drew up the plans I considered the problem of possible overheating in the Summer and that also became a part of the design. It can be cooler in the rear of the greenhouse in the Summer than it is in the

Winter. The combination of both these things is causing the plants to be confused. Plants going into bloom in the Fall and Winter is a very pleasant surprise and maybe I can claim I

planned it that way.

Meu Gardens

Gradina ornamentale

Fructe și legume gradina

O privire mai atentă în grădină.

Primăvara 2007 prune blossums

Meu Gardens şi grădinărit.Au fost grădinărit de mai mulţi ani cu grădini în pustie (Phoenix, AZ), altitudini mari

(Flagstaff, AZ) şi aici în Wisconsin. Meu grădini şi Gradinarit reprezintă o parte importantă din viaţa mea. În afară de valoare terapeutică că grădinărit prevede, în

creştere propriul meu alimente permite-mi să aleagă varietățile vreau să mănânc. Am posibilitatea să alegeți soiuri pentru gust mai bun şi valoarea nutritivă. Cele mai multe opţiuni, veţi găsi în supermarketuri sunt cele care nava şi stoca bine şi pot fi tratate cu

erbicide şi pesticide, sau eventual contaminate cu E-coli şi să nu uităm culturi OMG care merg neetichetat pe rafturile magazin. Dacă aveţi propria gradina te pentru a alege ceea ce

mănâncă şi cum acesta a fost crescut.

Am să crească cele mai multe dintre meu plante din semințe. Care dă-mi posibilitatea de a încerca plante care doar nu găsiţi în altă parte. Da, unele seminţe poate fi foarte dificil de a

germina, dar se bucură de provocare. Nu am nimic împotrivă aşteptaţi suplimentare pentru plante să se maturizeze, pentru că puteţi selecta din răsaduri cel mai bun şi de a

avea plante superioare, pe termen lung, și la un cost mult mai mici. Cu copaci aveţi nevoie pentru a avea o perspectivă pe termen lung despre grădinărit. Multe dintre arborii din fotografii au fost cultivate din seminţe şi acum sunt producătoare de fructe. Nu vin, de

obicei, adevărat din semințe de pomi fructiferi, dar care oferă oportunităţi pentru a avea ceva unic în gradina ta. Cu un pic de reproducere ştii cum şi corectă selecţii unele foarte înaltă calitate fructiferi pot fi produse prin gradinar cu experienţă. Este nevoie de ceva

timp pentru a afla mai fina puncte de grădinărit, dar este bine merită efortul.

Întotdeauna am să încercaţi ceva nou sau diferite. Fiecare ianuarie am cutreiera cataloage de seminţe şi de căutare pe Internet pentru acele lucruri care prinde ochiul meu. Am, de

obicei, doresc mai multe soiuri noi mai mult decât eventual ar putea creşte şi după efectuarea afară meu doresc lista, aleg de cele care nu pot face fără. Ei bine, am, probabil,

ar putea dar alege să nu. Soţia mea înţelege acest most de la timp. Ea are cea mai mare parte de lucru cu grădină de flori şi containere de lângă casa. Fructe și legume de grădină

sunt responsabilitatea mea. Am cresc, de asemenea, o varietate de boabe mici în Grădina să moară în făină. Meu cu efect de seră dă-mi şansa de a creşte de plante care altfel nu ar fi

posibil. În ea am crească: pitică citrice, căpșuni guava, mai multe soiuri de cactus, etc... Se deschide o mulţime de opţiuni pentru mine. Check out imagini şi articolul de mai jos.

Imagine a mea Solar cu efect de seră doar după finalizarea.

Containerul plante în spatele seră cultivate.

Nou plantate paturi în prima parte a iernii.

Primăvara timpurie după primul sezon de iarnă aplicaţii. Dacă aţi compara imaginile veţi vedea că creșterea considerabilă a apărut prin iarna şi

cele mai multe tot de plante au supraviețuit destul de bine.

Se închide de plante Tower bijuteriile. A crescut de peste şase picioare înalt și era acoperit cu sute de blooms. Instalația de Turnul bijuteriile este o Bienala mai

potrivite pentru California decât Prairie Farm, Wisconsin.

Meu solare cu efect de serăRăspunsul rapid a ceea ce un is. adevărat seră Solar cu.... este că este capabil de colectare toate energia care are nevoie de lumina soarelui să mențină temperaturi corespunzătoare pentru supravieţuire vegetale şi de creştere. Dar nu este aşa de simplu. Are, de asemenea,

să se poată stoca şi distribui excesul de căldură pentru acele zile când soarele nu straluceasca. Aici, în fermă Prairie, WI (zona 3) soarele are un urât obiceiul de a nu străluceşte atunci când este necesară cea mai mare parte în toamna și iarna târziu.

Dorea o seră de mai mulţi ani, dar nu ar putea justifica cheltuielile de încălzire unul prin rece luni. Aici înseamnă că cel puțin octombrie prin aprilie, şi, probabil, părți ale mai şi septembrie, de asemenea. Există planuri pentru sere solare acolo pe Internet şi există mai

multe cărţi care au fost publicate pe această temă. Desene sau modele oferite ar efectua bine în zona 5 şi în sus, dar am îndoit dacă acestea ar fi suficientă pentru meu climatice. Ei, de asemenea, a avut creştere spaţiul limitat pentru dimensiunea lor. După ce a învăţat ceea ce am putut din surse disponibile, am luat un pas hotărâtor şi proiectat propria mea având în minte nevoile mele şi vrea şi, de asemenea, abilitatea de a construi o. Mare vise niciodată deveni realitate, dacă acestea sunt dincolo de mijloacele dumneavoastră pentru a le realiza.

Deci, cu planuri de mână m-am dus despre sarcina de asamblare materialele necesare pentru construirea de acesta. Costurile au fost aproximativ 1.200 $ la locale de uscare a

lemnului metri. Acestea ar fi fost mult mai mult în cazul în care nu au luate avantaj materiale gratuite la prieteni şi vecini. Cu unele ajutor setarea căpriori şi astfel,

reformularea a fost sus. Finisare a avut mai mult de aşteptat. Trebuie acordată o atenție deosebită pentru a se asigura că nu există nici o infiltrare de aer de evacuare termică

exterioară sau nedorit din interiorul seră. Umiditate migrării în zidurile este o problemă foarte gravă şi nu trebuie să fie autorizate, atât de bandă sus fiecare intercalaţie în barieră de umiditate. Doriţi să aveţi control complet asupra fluxului de aer și se încălzește în afară

de seră. Green cherestea tratate este o trebuie să dacă geamurile îndeplinește cadru și umiditate oriunde va fi întâlnite şi dacă aveţi îndoieli, utilizaţi verde cherestea tratate

exclusiv în construcția.

Veţi observa din imaginile mele cu efect de seră numai a geamurilor cu care se confruntă Sud. Aceasta este practica cea mai comună cu sere solare. Este cea mai mare de energie eficient mod și plante încă primi o multime de lumina soarelui. Cele mai multe nu au un

perete de genunchi geam ca mea are. Într-o zonă cu o mulţime de ninsoare aceasta permite pentru zăpadă diapozitiv de pe acoperiş geamuri și să nu blocheze lumina soarelui.

Aceasta permite, de asemenea, pentru o mai mare înălțime deasupra paturi plantare şi mai uşor accesul la acestea. Nu shoveling zăpadă şi maximizarea spaţiului interior au fost important pentru mine. Am ales, de asemenea, un unghi de 45 grade pentru acoperiş

geamurilor, care nu este teoretic mai bun unghi pentru această amplasare. Doriţi razele soarelui să fie aproape perpendicular pe geam atunci când soarele este la său cel mai scăzut

la începutul iernii, pentru a maximiza câştig de căldură. Am două lucruri de spus despre asta. În primul rând, soare disponibile în acest moment al anului în acest domeniu este foarte limitată şi veţi obţine foarte puţină căldură câştig, atunci când nu este străluceşte Soarele. În al doilea rând, prin alegerea unghi de 45 grade, permis mine pentru a utiliza cherestea lungimea standard cu aproape nici un deșeu. Aceasta reduce costurile şi a-mi

voie să petreacă mai mult în alte domenii care a făcut mai mult pentru pierderile teoretice.

Acum hai sa vorbim despre izolare. În proiectarea de seră, peste căpriori dimensiuni şi ştifturi trebuie utilizate pentru a se potrivi grosimea bolizi nevoie de izolare. Am folosit R

23 în partea de Nord se confruntă cu perete şi acoperiş şi R-19 în est și vest se confruntă cu pereţi. În interiorul am folosit alb coli styrofoam ca un bun lumină perete reflectorizant de

acoperire şi ca adăugat izolația, două inci grosime la nord cu care se confruntă perete şi

plafon şi 1 1/2 inch gros pe pereţi. În, în și din afara bază de seră este un strat de grosime de îngropat două inci de styrofoam pentru a menţine îngheț la Noţiuni de bază în de seră.

Geamul este panoul dublu pe rânduri inferioară de panoul de sticlă şi triplu pe rând superioară din sticlă.

Stocare de căldură este realizat două moduri în seră. Primul mod este de apă de colectare și de depozitare. Am un galon 300 stoc rezervor şi cinci 55 galoane tobe în seră pentru a

stoca energie termică. În al doilea rând, şi nu pentru a fi trecute cu vederea, o mare cantitate de energie termică este stocată în plantare paturi şi podea de seră. Căldura

stocată în paturi plantare este o necesitate pentru a menţine pete rece la dezvoltarea lângă le şi căldură stocate în aria planșeului pasiv încălzește seră când nu lui străluceşte Soarele.

Căldură stocate în rezervoare de apă este nu în cazul în care este necesar. Acesta este eliberat în partea din spate a seră şi se ridică la vârf. Pentru a rectifica acest lucru am

folosi un fan mici la vârf de seră pentru a forţa de căldură înapoi în jos şi, de asemenea, acest lucru elimină petele rece.

Cea mai buna locatie pentru meu cu efect de seră a fost unele distanța de casa mea şi nu lângă putere sau apă. Ambele din aceste probleme au fost uşor pentru a corecta. Apă sunt

colectate de la acoperişul de cu efect de seră în cantități suficiente mai mult. Pentru a executa fan necesare şi iluminat în de seră, un panou solar mici este utilizat pentru taxa de o baterie de masina de 12 volţi şi ţine lucrurile să fie difuzate. De asemenea, acum am un generator de vânt micro parametrizat alăturată de seră pentru acele zile când soarele nu cooperează. Panoul de control a fost alcătuite din părţi am avut de stabilire a jur. Nu este

foarte frumoasă, dar nu loc de muncă. Orificiu automată este tipul de cilindru ceară şi necesită nici o putere să funcționeze.

Ca oamenii, sere au propriile lor personalitati, şi este nevoie de un pic de timp pentru a ajunge la le cunosc. Meu mai mare surpriză a fost că aceasta a funcționat destul de mult de

modul în care am avut planificate. Are grijă de ea însăşi most de la timp şi dacă a instala automată adăpare sistem l-ar putea să nu nevoie de mine la toate. glumeam. Ea a luat-mă prin două sezoane acum şi m-a invatat unele lucruri pe drum. Viziunea mea de a fi plin de plante ca unele jungla tropicală nu funcţionează. Este prea restrictive pe fluxul de lumina soarelui în seră. Plantele luat o multime de lumina soarelui, dar de stocare de căldură nu. Aceasta conduce la supraîncălzire aerului în seră, dar o scădere globală de căldură stocate

în de seră. Acest lucru a cauzat mai mare temperatură leagăne în interiorul seră și a pierderii de unele dintre mea plante tropicale. Au cerut o temperatură puțin mai mare

decât seră menținut acest sezon, dar se pare că cele mai multe dintre plantaţii venit prin cu minim sau o deteriorare care le. Mi-a luat un pic de timp sa gasesc acest lucru deoarece

primul sezon a mers aşa de bine. Plantele au fost mai mici atunci și nu au fost o problema. Pruning mai multe şi mai puţin densă de plantare va vindeca problema.

Alte interesant lucru care sa întâmplat este că unele de plante din spate de seră au trecut sezoane creştere accesând latente sau semi-dormant în vara și având lor principală de

creştere în iarna. Cred că acest lucru este un rezultat neintenţionate de meu de design. Am ştiut că ar fi mai puţin de lumină în spatele seră in vara, dar încă o multime de lumină

pentru creșterea plantei corespunzătoare. Când am elaborat planuri am considerat problemă de supraîncălzire posibil în vara şi care, de asemenea, a devenit o parte a

desenului sau a modelului. Poate fi mai răcoare în spate cu efect de seră în vara decât este în iarna. Combinație de ambele aceste lucruri este cauza plante să fie confundate. Plante

întâmplă în floare în toamna și iarna este o surpriza foarte placuta si poate poate pretinde am planificat-o în acest fel.

* Nou * imagini şi conţinutul de pe pagina tehnologia corespunzătoare şi energie alternativă a acestui website.

Aflati mai mutle despre cum utilizează vânt şi solare putere la puterea mea cu efect de seră.

Actualizare 1 februarie 2011. Acest toamna și iarna, până în prezent, a fost

Constructing a Simple PVC High Tunnelby Jim Hail, Robbins Hail, Katherine Kelly, and Ted Carey

Introduction

This low-cost, 30’ long by 18’ wide high tunnel is constructed using PVC pipe for hoops. The materials cost roughly $500 (including shade cloth for summer production) and we didn't shop for the best buy on materials and lumber. A slight disadvantage of the design is that curvature of the hoops may allow rain to run inside the edge of the house when the sides are raised for ventilation. One person can complete most of the construction, but inserting the hoops and putting on the plastic requires at least two people. Also, it is nice to have someone to share the heavy work of driving in the ground posts. A crew of four can easily construct a high tunnel of this design in a single day.

LINK:How to Build a High

Tunnel by Amanda Ferguson, University

of Kentucky

The dimensions of this high tunnel design may be scaled-down if you have limited space available for your high tunnel. At a lesser diameter, or in well-protected locations, it may be possible to use 1” PVC for the hoops, with 1½” PVC for the posts. The length of pipe to use for hoops may be calculated using the formula for the circumference of a circle, (3.14)r, where r is half the width of your tunnel. Add 3’ to insert into the ground posts.

LINK:Hoop House

Construction for New Mexico:

12ft X 40ft Hoop House

PVC will react with the polyethylene greenhouse covering, so in order to attain the expected 4-year life span of the plastic, measures should be taken to prevent contact between the PVC and the polyethylene covering. This may be done by painting or taping the side of the PVC hoops that will be in contact with the plastic. Having said that, the oldest high tunnel at Bear Creek Farm in Osceola, Missouri, is eight years old and is still covered by its original plastic, which is in contact with the PVC hoops.

Note: Our procedure calls for driving 3’-long PVC posts into the ground after laying out the baseboards. We have found this to be a convenient way to proceed. However, in shallow, tight or stony soils, it may be necessary to dig holes using an augur, and then set the posts in concrete. If it is likely that you will need to do this, then posts should be set before laying out the baseboards.

Materials

Material Dimension Quantity Notes

Twine & Pegs For corner and baseboard layout.

Lumber 2" x 6" x 10’ 6

For baseboards. The boards will be in contact with the soil, so you might consider a rot resistant wood, such as cedar or redwood. If you will be growing food crops in the tunnel, it’s probably best not to use treated lumber because of possible health concerns.

1" x 4" x 10’ 6 For hip boards.

2” x 4” x 8' 18Lumber for attaching baseboards, bracing end hoop, and framing end-walls.

2” x 4” x 10' 4Lumber for framing doors. Depending on door size, amount of bracing desired amount may vary. We put a 32”-wide door on each end.

Furring strips 1" x 2" x 10’ 12

For attaching plastic to hip boards and end-walls. Poly tape may also be used for attaching plastic to end walls. Wiggle wire is a more costly but convenient method for attaching plastic to hip boards.

Schedule 40 PVC pipe

1½” x 20’ bell-end

12 For 11 hoops + purlin.

10’ x 1½”

straight-end 12 For 11 hoops + purlin.

3’ pieces of

2” 22 For ground posts. Requires 8 10' pieces

Primer & Glue . . For connecting PVC pipe

Carriage bolts 4½” x ¼” 33For attaching hoops and posts to baseboards, and hoops to purlin – purchase bolts, washers and nuts.

Deck screws 1½” 1 lb

2½” 2 lb

3½” 2 lb

Chain link fence top rail

31' 2 For roll up sides.

PVC fittings 1” . To make handles for roll up sides.

Self-tapping screws

. .For connecting top rail pieces, and for attaching PVC handle to roll-up side.

Greenhouse polyethylene

30’ x 34’ 1

For covering the house use 6 mil UV stabilized. For the end walls, you may use a lighter gauge material, since it may be taken off each summer to enhance ventilation.

Shade cloth 30’ x 25’ 1 White 38% shade cloth with grommets sewn every 3’.

Tools

Step ladder

Level and plumb line

Stapler and staples

Sledge hammer for driving baseboard stakes and PVC ground posts

Saw for cutting lumber and PVC

Drill with screwdriver bit, and with extended ¼” wooden drill bit for drilling holes for carriage bolts

Site Preparation and Construction

1. Site Preparation. Choose a good site for locating the tunnel with respect to light, drainage, access, irrigation, etc. Prior to beginning construction you may wish to build a slightly elevated, level pad, or take other measures to ensure that run-off water will not flood the high tunnel, particularly in the winter. Orientation with respect to wind is not critical, but we have oriented ours east west, meaning that prevailing winds are usually from the sides.

2. High Tunnel Layout. Mark the corners of a rectangular area 18’ wide by 30’ long. Make corners square by ensuring an equal distance between perpendicular corners (should be 35’ between outer corners of pegs). Drive 2”x2” peg into the ground at the corners and stretch twine around the outsides of the corner posts where baseboards will run. It is not essential for the tunnel to be level, but this certainly helps to make doors square. To layout a level tunnel, use a level to adjust the height of the string to be used as a guide for baseboard placement. We have built ours on slight slopes, with the baseboards following the slope, and hip boards parallel to the baseboards.

3. Set Baseboards. Cut 14 2’ pieces of 2”x4”, and cut points on ends for driving into the ground. Drive in these stakes for baseboard attachment on the inside of the guide string, orienting the broad side of the 2”x4” parallel to the string. For the long sides of the tunnel, posts should be 10’ from each end (where the baseboards will meet) and 6” from the ends (to allow space for PVC ground posts). Attach the 2”x6”x10’ side baseboards to the pegs using 3½” screws, starting at one end (snug with the corner peg). For the end walls, place a peg 10’ from the outer edge of one of the sideboards, and 6” from each of the corners. Attach the first 2”x6”x10’ (snug against the end of the sidewall baseboard) and cut the second one to fit.

Figure 1. Baseboards laid-out ready for ground post installation.

4. Drive in Ground Posts. Mark inside of side baseboards at 3’ spacing starting from the end of the sidewall baseboard. Remove corner pegs and string and drive in PVC ground posts at corners and at 3’ marks. Posts should go in roughly to the top of the baseboard, at most. It is possible to damage the PVC by hitting it too hard with the sledgehammer, or trying to force it through tight or stony soil. To avoid damaging PVC with the sledgehammer, have a helper hold a length of 2”x4” over the end of the pipe, and pound on the 2”x4”. The helper should wear gloves to protect against jolts.

Note: Our procedure calls for driving 3' PVC posts into the ground after laying out the baseboards. However, in shallow, tight or stony soils, it may be necessary to dig hole using an augur, and then set the posts in concrete. If it is likely that you will need to do this, then posts should be set before laying out the baseboards.

Figure 2. Ground posts ready to be driven in.

Figure 3. Ground posts damaged during pounding. This can be prevented by pounding on a 2"x4" rather then directly on the PVC pipe.

5. Hoop Assembly. Assemble 30’ hoops and purlin by gluing together 10’ and 20’ PVC pipes. Use PVC primer and glue, following instructions for correct use of products.

Figure 4. Hoops being placed in ground posts.

6. Raising Hoops. Erect hoops by inserting one end into a 2” PVC ground post, and bending the hoop to insert into the ground post opposite on the other side of the tunnel. Make sure that ends of hoops extend well into the ground posts (at least 12”). After inserting the posts, make minor adjustments in the height of the hoops (sight along the top of the hoops from a ladder) so that all are at the same height. Drill through baseboard and pipes with ¼” wooden drill bit. Attach using carriage bolts, washers and nuts, pushing the bolt through from the outside, and tightening the hoops snug to the baseboard

Figure 5. Drilling through baseboard, ground post and hoop. Carriage bolts will hold hoop in place.

7. Purlin Attachment. Attach purlin (30' 1½ PVC pipe) to the inside of the hoops. Drill through purlin and hoops at 3’ spacing, and attach using carriage bolts, washers and nuts. Head of the bolt should be up to present a smooth surface to the poly that will cover the tunnel. We put a piece of duct tape over the top of the carriage bolt before putting the poly on the hoops.

Figure 6. Tunnel with purlin and hip board in place.

8. Hip Board Attachment. Attach hip boards at 3’ height using 1½” screws. Mark hoops 3’ above baseboard, and attach 1”x4”x10’s end to end, starting at one end of the tunnel. Ends of hip boards may be secured together where they meet by screwing a block of wood across the inside of the junction.

Figure 7. Hip board in place.

9. End wall Construction. Use 2”x4” lumber to frame in end walls. There is no hard and fast rule for end wall design. However the attached picture shows our general design consisting of four uprights reinforced by horizontal and diagonal bracing. Spacing door uprights at a standard distance (32”, 34” or 36”) accommodates standard door sizes. Cut notches in the uprights to fit the inside of the baseboard or the hoop, and attach using 2½” or 3½” screws.

Figure 8. Tunnel showing end wall design at K-State Research and Extension Center, Olathe, Kansas.

Figure 9. Tunnel showing end wall design at Full Circle Farm, Kansas City, Kansas.

10. End wall Bracing. Attach end wall bracing. Cut 2”x4” lumber to run from baseboard close to the second hoop, and attach to end wall and baseboard.

11. Plastic Preparation. Attach furring strips end to end along the upper half to the hip boards. Alternatively attach the channel for wiggle wire using self tapping screws.

12. Plastic Attachment. It is best to do this on a calm day. Lay out the poly lengthwise on one side of the high tunnel. If you are cutting from a longer roll of plastic, be sure to leave 2’ extra on each end to allow for attaching to the end walls. Pull plastic over the tunnel. A simple way to do this is to secure a rope close to the edge of the poly at each end of the tunnel by placing an object such as a tennis ball under the plastic and tying the rope around it through the plastic. Then the rope is thrown over the tunnel and the plastic pulled over the tunnel using the rope. Make sure the plastic is well centered on the tunnel and then attach by placing furring strips over the plastic, snug against and just below the furring strips already attached to the hip board. Attach the furring strips with 1½” screws, placed every 2 or 3 feet. Pull the plastic tight and attach to the other side in the same way. Finish securing the plastic by attaching to the end walls using additional furring strips. Note, you may also use poly tack strips (commercially available).

Figure 10. Poly attachment to hip board using one furring strip. This method is less secure than others since poly tends to tear at the screws.

Figure 11. Picture showing the 2-furring strip method of attaching poly to the hip board.

13. Roll-up Side Installation. Attach roll-up sides. Assemble top rail pieces to roll up sidewall plastic with. Make sure the pipe is longer than the tunnel on both ends so that you can attach a handle to it, and to avoid difficulties with rolling up sides. Attach the pipe to the poly. We have used duct tape for this, but a better option is to use special clips for attaching poly to pipe, which are available from commercial sources. An alternative is not have roll-up sides at all, but to simply tie up poly when ventilation is required. This is easily done by placing eye-hooks in the hip board at each hoop, and running a piece of string below the sidewall poly, around the hoop and back. Both ends of the string are tied to the eye-hook. For roll-up sides, various options are possible, figure 8 shows a PVC crank that we have used.

Figure 12. Poly attachment to hip board using wiggle wire.

14. Stabilize Sidewalls. Prevent sidewalls from billowing. To prevent sidewalls from flapping in the breeze, some sort of support is needed to help keep them in check. Pieces of used drip tape running from the hip board to the baseboard at each hoop is effective for us. Using a fender washer along with the screw prevents screws from tearing though the drip tape in high winds

Figure 13. A drip tape strip from hip board to base board at each hoop can keep side walls from billowing.

15. Install plastic on the end walls. Since we take off the end wall plastic during the summer months, we use a lower thickness end wall plastic. Either commercially available poly tack strip or furring strips may be used to secure a sheet of plastic completely over the end wall. Then a hole may be cut for the doorway.

For more on

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Resources

16. Frame Door. You can make a door, or use an old door on one or both ends of the tunnel.

17. Shade Cloth Installation. Shade cloth helps keep temperature down during the summer in high tunnels. In hot years, we put ours on from Memorial Day to Labor Day. Grommets sewn into the cloth every three feet allow for tying down to eye hooks fixed into the baseboards. We skew the shade cloth toward the south in order to provide better shading on that side.

About the Authors

Robbins and Jim Hail own and operate Bear Creek Farm in Osceola, Missouri.

Katherine Kelly owns and operates Full Circle Farm in Kansas City, Kansas.

How to Build a PVC Hoophouse for your GardenWritten by Travis Saling

Send questions or comments to trav@westsidegardener.com

An unheated PVC hoophouse can be a useful addition to your garden. It keeps excessive rain off the plants, blocks the wind, raises daytime temperatures 5-10 degrees (and often much more), and keeps frosts and heavy dew off the leaves. This can extend your warm-season gardening a month or more at both ends, and makes it possible for year-round gardeners to grow a wider variety of plants through the winter.

PVC hoophouses are inexpensive to build, and can be put up in about an hour. Take a look, and decide for yourself!

Parts list for a 10'x21' PVC hoophouse

1/2-inch heavy duty PVC pipe (30-inch lengths), for stakesAlternative material: Rebar, cut to length

16

3/4-inch light duty PVC pipe (10-foot lengths), for ribs - schedule 16

125 works bestCheck that the 1/2" pipe fits inside of the 3/4" pipe while you're still at the store!

3/4-inch light duty PVC pipe (34-inch lengths), for ridgeline 7

3/4-inch PVC tee connector (3-way) 2

3/4-inch PVC cross connector (4-way) 6

20'x25' sheet of clear visqueen-type plastic ( NOT greenhouse plastic)

1

1-inch black poly pipe (8-inch lengths), for clips 16

Optional: 1/2-inch PVC pipe (12-inch lengths), to reinforce joints 8

Optional: 10'x25' sheet of clear plastic, for ends 1

Optional: Large binder clips 12

Tools needed:hacksaw (for cutting PVC and poly pipe to length)rubber mallet (for snugging up joints)utility knife (to slit poly pipe lengthwise)25' tape measuredrill with 5/8" spading bit (if internally reinforcing joints)

Total amounts of pipe to be purchased

5 10'-lengths of 1/2" PVC19 10'-lengths of 3/4" PVC11' of 1" poly pipe

Before getting started, you need to mark out where in the garden your hoophouse will be placed. The diagram to the right

gives you the distances for the hoophouse I am describing; but you can easily modify it to the size you need. As described, this 10'x21' PVC hoophouse will be roughly 7' tall in the center.

To ensure that the sides are all parallel and square, measure across the diagonals: Both distances should be the same.

The first thing to do is collect all your separate parts. The construction will go much quicker if you have a helper.

Drive a stake into the ground every 36 inches along the two sides (this is much easier if you cut the bottom of the stake at an angle). Try to get them as straight up as possible.

I find it easiest to put up all the separate hoops first, then connect the ridge afterward. Each of the two end hoops is made using two 10' lengths of 3/4" PVC, joined with a PVC tee. The other six hoops use the PVC crosses in place of the PVC tees. Since I like to be able to move the hoophouse around the garden from season to season, the joints are dry-fit together (no glue). They seem to stay together, especially if I use a rubber mallet to snug up all the connections.

Optional step: I have found that the joints mentioned above are sturdier if I reinforce them internally, by inserting a 1-foot length of 1/2" PVC through the joint. These pieces seem to fit through a 3/4" PVC tee okay; but you may have to drill out the PVC crosses in one direction, using a 5/8" spading bit. This can be tricky, so be sure to clamp the cross down well BEFORE attempting to drill it out!

The two ends of each hoop slide easily over the 1/2" PVC stakes. If the stakes aren't in the ground perfectly straight, don't worry about it; the pressure from the hoops tends to even out their alignment somewhat.

When setting up the hoops, having that helper around REALLY makes things easier.

The next step is to connect the ridgeline. Starting at one end of the hoophouse, connect the hoops at the top, using the 34-inch sections of 3/4" PVC. As I go, I like to use the rubber mallet to set

each section as far into the connectors as possible. Note that the ridgeline will be slightly shorter than 21 feet, for increased stability.

Congratulations! You have finished the frame!

The plastic sheeting can be secured to the frame in many ways. 8-inch lengths of 1-inch black poly pipe can be slit lengthwise, making clips which can hold the plastic onto the PVC frame. A slightly more expensive solution is to use large binder clips, which can be found at any office supply store.

I like to sandwich the sides of the plastic with 2x4 lumber, screwed together. When it gets

windy, this extra weight holds the plastic down much better than the clips alone.

All sorts of heat-loving plants thrive in a hoophouse environment, including tomatoes, peppers, and, unfortunately in this case, horsetail.

Making the Optional Ends

This goes much easier if it's done before the frame is "skinned" with the 20'x25' plastic sheet.

Cut the 10'x25' piece of clear plastic to make two 10'x12.5' pieces. Take one, and lay it over one end hoop of the PVC hoophouse (the 10' measurement should be vertical), such that the hoop is completely covered, but at least one foot of plastic is on the ground. Use the poly pipe clips to

secure this plastic end piece to the hoop. Cut a slit down the middle to make the door. There will be some excess plastic, which can be cut off if desired. That's it! Repeat this at the other end of the PVC hoophouse. These "doors" can be tied open with twine, or held shut with weights such as bricks or water jugs (which is why that extra foot of door, laying on the ground, is necessary).

It has been my experience that the poly pipe clips do not hold well if they are used over two layers of plastic. So I use the poly clips to secure the end pieces to the end hoops, and then hold the walls in place using the large binder clips.

Further Notes

Although I use the more inexpensive PVC for the 3/4" ribs, I have found it worthwhile to purchase the heavy gauge 1/2" PVC for the stakes. When the wind catches the hoophouse broadside, the stakes experience a lot of stress at the point they enter the ground. The thicker the wall of the pipe is, the less likely it is to break. One gentleman wrote and suggested inserting Rebar inside the stakes, which certainly would be worthwhile in an unusually windy location. Since any stress on the ribs is spread over their entire length, there isn't much point in getting the thick-walled 3/4" PVC. Also, the thicker PVC will be less flexible, and in addition it may not fit over the 1/2" pipe used for stakes and reinforcement.

In most cases, I have found the weight of the 2x4s (used to hold down the plastic) sufficient to keep everything in place. People in very windy spots may need to further secure these either with ground anchors or by pounding Rebar into the ground (using it as you would a tent stake).

In case it isn't clear: All clamping with binder clips or home-made poly pipe clips is at the ends of the hoophouse (at the ends of the plastic sheeting, in other words). Putting them in the middle will just guarantee that you will lose them as soon as the wind rises. It's also a good idea to clamp the plastic while it is dry - even a thin film of water between the plastic and the PVC pipe greatly decreases the holding power of any clamps.

The most commonly asked questions are answered in the FAQ about the PVC Hoophouse.

Planning and Building a Greenhouse

Adapted from Fact Sheet 645 - University of Maryland Cooperative Extension Service, David S. Ross, Extension Agricultural Engineer, Department of Agricultural Engineering

Location Types of Greenhouses Structural Materials

Foundations & Floors Heating Air Circulation

Ventilation Cooling Watering Systems

Careful planning is important before a home greenhouse project is started. Building a greenhouse does not need to be expensive or time-consuming. The final choice of the type of greenhouse will depend on the growing space desired, home architecture, available sites, and costs. The greenhouse must, however, provide the proper environment for growing plants.

Location The greenhouse should be located where it gets maximum sunlight. The first choice of location is the south or southeast side of a building or shade trees. Sunlight all day is best, but morning sunlight on the east side is sufficient for plants. Morning sunlight is most desirable because it allows the plant's food production process to begin early; thus growth is maximized. An east side location captures the most November to February sunlight. The next best sites are southwest and west of major structures, where plants receive sunlight later in the day. North of major structures is the least desirable location and is good only for plants that require little light.

Deciduous trees, such as maple and oak, can effectively shade the greenhouse from the intense late afternoon summer sun; however, they should not shade the greenhouse in the morning. Deciduous trees also allow maximum exposure to the winter sun because they shed their leaves in the fall. Evergreen trees that have foliage year round should not be located where they will shade the greenhouse because they will block the less intense winter sun. You should aim to maximize winter sun exposure, particularly if the greenhouse is used all year. Remember that the sun is lower in the southern sky in winter causing long shadows to be cast by buildings and evergreen trees (Figure 1).

Good drainage is another requirement for the site. When necessary, build the greenhouse above the surrounding ground so rainwater and irrigation water will drain away. Other site considerations include the light requirements of the plants to be grown; locations of sources of heat, water, and electricity; and shelter from winter wind. Access to the greenhouse should be convenient for both people and utilities. A workplace for potting plants and a storage area for supplies should be nearby.

Types of Greenhouses

A home greenhouse can be attached to a house or garage, or it can be a freestanding structure. The chosen site and personal preference can dictate the choices to be considered. An attached greenhouse can be a half greenhouse, a full-size structure, or an extended window structure. There are advantages and disadvantages to each type.

Attached GreenhousesLean-to. A lean-to greenhouse is a half greenhouse, split along the peak of the roof, or ridge line (Figure 2A), Lean-tos are useful where space is limited to a width of approximately seven to twelve feet, and they are the least expensive structures. The ridge of the lean-to is attached to a building using one side and an existing doorway, if available. Lean-tos are close to available electricity, water and heat. The disadvantages include some limitations on space, sunlight, ventilation, and temperature control. The height of the supporting wall limits the potential size of the lean-to. The wider the lean-to, the higher the supporting wall must be. Temperature control is more difficult because the wall that the greenhouse is built on may collect the sun's heat while the translucent cover of the greenhouse may lose heat rapidly. The lean-to should face the best direction for adequate sun exposure. Finally, consider the location of windows and doors on the supporting structure and remember that snow, ice, or heavy rain might slide off the roof or the house onto the structure.

Even-span. An even-span is a full-size structure that has one gable end attached to another building (Figure 2B). It is usually the largest and most costly option, but it provides more usable space and can be lengthened. The even-span has a better shape than a lean-to for air circulation to maintain uniform temperatures during the winter heating season. An even-span can accommodate two to three benches for growing crops.

Window-mounted. A window-mounted greenhouse can be attached on the south or east side of a house. This glass enclosure gives space for conveniently growing a few plants at relatively low cost (Figure 2D). The special window extends outward from the house a foot or so and can contain two or three shelves.

Freestanding StructuresFreestanding greenhouses are separate structures; they can be set apart from other buildings to get more sun and can be made as large or small as desired (Figure 2C). A separate heating system is needed, and electricity and water must be installed.

The lowest cost per square foot of growing space is generally available in a freestanding or even-span greenhouse that is 17 to 18 feet wide. It can house a central bench, two side benches, and two walkways. The ratio of cost to the usable growing space is good.

When deciding on the type of structure, be sure to plan for adequate bench space, storage space, and room for future expansion. Large greenhouses are easier to manage because temperatures in small greenhouses fluctuate more rapidly. Small greenhouses have a large exposed area through which heat is lost or gained, and the air volume inside is relatively small; therefore, the air temperature changes quickly in a small greenhouse. Suggested minimum sizes are 6 feet wide by 12 feet long for an even-span or freestanding greenhouse.

Structural Materials

A good selection of commercial greenhouse frames and framing materials is available. The frames are made of wood, galvanized steel, or aluminum. Build-it-yourself greenhouse plans are usually for structures with wood or metal pipe frames. Plastic pipe materials generally are inadequate to meet snow and wind load requirements. Frames can be covered with glass, rigid fiberglass, rigid double-wall plastics, or plastic film. All have advantages and disadvantages. Each of these materials should be considered--it pays to shop around for ideas.

FramesGreenhouse frames range from simple to complex, depending on the imagination of the designer and engineering requirements. The following are several common frames (Figure 3).

Quonset. The Quonset is a simple and efficient construction with an electrical conduit or galvanized steel pipe frame. The frame is circular and usually covered with plastic sheeting. Quonset sidewall height is low, which restricts storage space and headroom.

Gothic. The gothic frame construction is similar to that of the Quonset but it has a gothic shape (Figure 3). Wooden arches may be used and joined at the ridge. The gothic shape allows more headroom at the sidewall than does the Quonset.

Rigid-frame. The rigid-frame structure has vertical sidewalls and rafters for a clear-span construction. There are no columns or trusses to support the roof. Glued or nailed plywood gussets connect the sidewall supports to the rafters to make one rigid frame. The conventional gable roof and sidewalls allow maximum interior space and air circulation. A good foundation is required to support the lateral load on the sidewalls.

Post and rafter and A-frame. The post and rafter is a simple construction of an embedded post and rafters, but it requires more wood or metal than some other designs. Strong sidewall posts and deep post embedment are required to withstand outward rafter forces and wind

pressures. Like the rigid frame, the post and rafter design allows more space along the sidewalls and efficient air circulation. The A-frame is similar to the post and rafter construction except that a collar beam ties the upper parts of the rafters together.

Coverings Greenhouse coverings include long-life glass, fiberglass, rigid double-wall plastics, and film plastics with 1- to 3-year lifespans. The type of frame and cover must be matched correctly.

Glass. Glass is the traditional covering. It has a pleasing appearance, is inexpensive to maintain, and has a high degree of permanency. An aluminum frame with a glass covering provides a maintenance-free, weather-tight structure that minimizes heat costs and retains humidity. Glass is available in many forms that would be suitable with almost any style or architecture. Tempered glass is frequently used because it is two or three times stronger than regular glass. Small prefabricated glass greenhouses are available for do-it-yourself installation, but most should be built by the manufacturer because they can be difficult to construct.

The disadvantages of glass are that it is easily broken, is initially expensive to build, and requires must better frame construction than fiberglass or plastic. A good foundation is required, and the frames must be strong and must fit well together to support heavy, rigid glass.

Fiberglass. Fiberglass is lightweight, strong, and practically hailproof. A good grade of fiberglass should be used because poor grades discolor and reduce light penetration. Use only clear, transparent, or translucent grades for greenhouse construction. Tedlar-coated fiberglass lasts 15 to 20 years. The resin covering the glass fibers will eventually wear off, allowing dirt to be retained by exposed fibers. A new coat of resin is needed after 10 to 15 years. Light penetration is initially as good as glass but can drop off considerably over time with poor grades of fiberglass.

Double-wall plastic. Rigid double-layer plastic sheets of acrylic or polycarbonate are available to give long-life, heat-saving covers. These covers have two layers of rigid plastic separated by webs. The double-layer material retains more heat, so energy savings of 30 percent are common. The acrylic is a long-life, nonyellowing material; the polycarbonate normally yellows faster, but usually is protected by a UV-inhibitor coating on the exposed surface. Both materials carry warranties for 10 years on their light transmission qualities. Both can be used on curved surfaces; the polycarbonate material can be curved the most. As a general rule, each layer reduces light by about 10 percent. About 80 percent of the light filters through double-layer plastic, compared with 90 percent for glass.

Film plastic. Film-plastic coverings are available in several grades of quality and several different materials. Generally, these are replaced more frequently than other covers. Structural costs are very low because the frame can be lighter and plastic film is inexpensive. Light transmission of these film-plastic coverings is comparable to glass. The films are made of polyethylene (PE), polyvinyl chloride (PVC), copolymers, and other materials. A utility grade of PE that will last about a year is available at local hardware stores. Commercial greenhouse grade PE has ultraviolet inhibitors in it to protect against ultraviolet rays; it lasts 12 to 18 months. Copolymers last 2 to 3 years. New additives have allowed the manufacture of film plastics that block and reflect radiated heat back into the greenhouse, as does glass which

helps reduce heating costs. PVC or vinyl film costs two to five times as much as PE but lasts as long as five years. However, it is available only in sheets four to six feet wide. It attracts dust from the air, so it must be washed occasionally.

Foundations and Floors

Permanent foundations should be provided for glass, fiberglass, or the double-layer rigid-plastic sheet materials. The manufacturer should provide plans for the foundation construction. Most home greenhouses require a poured concrete foundation similar to those in residential houses. Quonset greenhouses with pipe frames and a plastic cover use posts driven into the ground.

Permanent flooring is not recommended because it may stay wet and slippery from soil mix media. A concrete, gravel, or stone walkway 24 to 36 inches wide can be built for easy access to the plants. The rest of the floor should be covered by several inches of gravel for drainage of excess water. Water also can be sprayed on the gravel to produce humidity in the greenhouse.

Environmental Systems

Greenhouses provide a shelter in which a suitable environment is maintained for plants. Solar energy from the sun provides sunlight and some heat, but you must provide a system to regulate the environment in your greenhouse. This is done by using heaters, fans, thermostats, and other equipment.

Heating The heating requirements of a greenhouse depend on the desired temperature for the plants grown, the location and construction of the greenhouse, and the total outside exposed area of the structure. As much as 25 percent of the daily heat requirement may come from the sun, but a lightly insulated greenhouse structure will need a great deal of heat on a cold winter night. The heating system must be adequate to maintain the desired day or night temperature.

Usually the home heating system is not adequate to heat an adjacent greenhouse. A 220-volt circuit electric heater, however, is clean, efficient, and works well. Small gas or oil heaters designed to be installed through a masonry wall also work well.

Solar-heater greenhouses were popular briefly during the energy crisis, but they did not prove to be economical to use. Separate solar collection and storage systems are large and require much space. However, greenhouse owners can experiment with heat-collecting methods to reduce fossil-fuel consumption. One method is to paint containers black to attract heat, and fill them with water to retain it. However, because the greenhouse air temperature must be kept at plant-growing temperatures, the greenhouse itself is not a good solar-heat collector.

Heating systems can be fueled by electricity, gas, oil, or wood. The heat can be distributed by forced hot air, radiant heat, hot water, or steam. The choice of a heating system and fuel depends on what is locally available, the production requirements of the plants, cost, and individual choice. For safety purposes, and to prevent harmful gases from contacting plants, all gas, oil, and woodburning systems must be properly vented to the outside. Use fresh-air vents to supply oxygen for burners for complete combustion. Safety controls, such as safety

pilots and a gas shutoff switch, should be used as required. Portable kerosene heaters used in homes are risky because some plants are sensitive to gases formed when the fuel is burned.

Calculating heating system capacity. Heating systems are rated in British thermal units (Btu) per hour (h). The Btu capacity of the heating system, Q, can be estimated easily using three factors:

1. A is the total exposed (outside) area of the greenhouse sides, ends, and roof in square feet (ft2). On a Quonset, the sides and roof are one unit; measure the length of the curved rafter (ground to ground) and multiply by the length of the house. The curves end area is 2 (ends) X 2/3 X height X width. Add the sum of the first calculation with that of the second.

2. u is the heat loss factor that quantifies the rate at which heat energy flows out of the greenhouse. For example, a single cover of plastic or glass has a value of 1.2 Btu/h x ft2 x oF (heat loss in Btu's her hour per each square foot of area per degree in Fahrenheit); a double-layer cover has a value of 0.8 Btu/h x ft2 x oF. The values allow for some air infiltration but are based on the assumption that the greenhouse is fairly airtight.

3. (Ti-To) is the maximum temperature difference between the lowest outside temperature (To) in your region and the temperature to be maintained in the greenhouse (Ti). For example, the maximum difference will usually occur in the early morning with the occurrence of a 0oF to -5oF outside temperature while a 60oF inside temperature is maintained. Plan for a temperature differential of 60 to 65oF. The following equation summarizes this description: Q = A x u x (Ti-To).

Example. If a rigid-frame or post and rafter freestanding greenhouse 16 feet wide by 24 feet long, 12 feet high at the ridge, with 6 feet sidewalls, is covered with single-layer glass from the ground to the ridge, what size gas heater would be needed to maintain 60oF on the coldest winter night (0oF)? Calculate the total outside area (Figure 4):

two long sides 2 x 6 ft x 24 ft = 288 ft2

two ends 2 x 6ft x 16 ft = 192 ft2

roof 2 x 10 ft x 24ft = 480 ft2

gable ends 2 x 6 ft x 8 ft = 96 ft2

A = 1,056 ft2

Select the proper heat loss factor, u = 1.2 Btu/h x ft2 x oF. The temperature differential is 60oF - 0oF = 60 oF.

Q = 1,056 x 1.2 x 60 = 76,032 Btu/h (furnace output).

Although this is a relatively small greenhouse, the furnace output is equivalent to that in a small residence such as a townhouse. The actual furnace rated capacity takes into account the efficiency of the furnace and is called the furnace input fuel rating.

This discussion is a bit technical, but these factors must be considered when choosing a greenhouse. Note the effect of each value on the outcome. When different materials are used in the construction of the walls or roof, heat loss must be calculated for each. For electrical heating, covert Btu/h to kilowatts by dividing Btu/h by 3,413. If a wood, gas, or oil burner is located in the greenhouse, a fresh-air inlet is recommended to maintain an oxygen supply to the burner. Place a piece of plastic pipe through the outside cover to ensure that oxygen gets to the burner combustion air intake. The inlet pipe should be the diameter of the flue pipe. This ensures adequate air for combustion in an airtight greenhouse. Unvented heaters (no chimney) using propane gas or kerosene are not recommended.

Air Circulation Installing circulating fans in your greenhouse is a good investment. During the winter when the greenhouse is heated, you need to maintain air circulation so that temperatures remain uniform throughout the greenhouse. Without air-mixing fans, the warm air rises to the top and cool air settles around the plants on the floor.

Small fans with a cubic-foot-per-minute (ft3/min) air-moving capacity equal to one quarter of the air volume of the greenhouse are sufficient. For small greenhouses (less than 60 feet long), place the fans in diagonally opposite corners but out from the ends and sides. The goal is to develop a circular (oval) pattern of air movement. Operate the fans continuously during the winter. Turn these fans off during the summer when the greenhouse will need to be ventilated.

The fan in a forced-air heating system can sometimes be used to provide continuous air circulation. The fan must be wired to an on/off switch so it can run continuously, separate from the thermostatically controlled burner.

Ventilation Ventilation is the exchange of inside air for outside air to control temperature, remove moisture, or replenish carbon dioxide (CO2). Several ventilation systems can be used. Be

careful when mixing parts of two systems.

Natural ventilation uses roof vents on the ridge line with side inlet vents (louvers). Warm air rises on convective currents to escape through the top, drawing cool air in through the sides.

Mechanical ventilation uses an exhaust fan to move air out one end of the greenhouse while outside air enters the other end through motorized inlet louvers. Exhaust fans should be sized to exchange the total volume of air in the greenhouse each minute.

The total volume of air in a medium to large greenhouse can be estimated by multiplying the floor area times 8.0 (the average height of a greenhouse). A small greenhouse (less than 5,000 ft3 in air volume) should have an exhaust-fan capacity estimated by multiplying the floor area by 12.

The capacity of the exhaust fan should be selected at one-eighth of an inch static water pressure. The static pressure rating accounts for air resistance through the louvers, fans, and greenhouse and is usually shown in the fan selection chart.

Ventilation requirements vary with the weather and season. One must decide how much the greenhouse will be used. In summer, 1 to 1� air volume changes per minute are needed. Small greenhouses need the larger amount. In winter, 20 to 30 percent of one air volume exchange per minute is sufficient for mixing in cool air without chilling the plants.

One single-speed fan cannot meet this criteria. Two single-speed fans are better. A combination of a single-speed fan and a two-speed fan allows three ventilation rates that best satisfy year round needs. A single-stage and a two-stage thermostat are needed to control the operation.

A two-speed motor on low speed delivers about 70 percent of its full capacity. If the two fans have the same capacity rating, then the low-speed fan supplies about 35 percent of the combined total. This rate of ventilation is reasonable for the winter. In spring, the fan operates on high speed. In summer, both fans operate on high speed.

Refer to the earlier example of a small greenhouse. A 16-foot wide by 24-foot long house would need an estimated ft3 per minute (cubic feet per minute; CFM) total capacity; that is, 16x24x12 ft3 per minute. For use all year, select two fans to deliver 2,300 ft3 per minute each, one fan to have two speeds so that the high speed is 2,300 ft3 per minute. Adding the second fan, the third ventilation rate is the sum of both fans on high speed, or 4,600 ft3 per minute.

Some glass greenhouses are sold with a manual ridge vent, even when a mechanical system is specified. The manual system can be a backup system, but it does not take the place of a motorized louver. Do not take shortcuts in developing an automatic control system.

Cooling Air movement by ventilation alone may not be adequate in the middle of the summer; the air temperature may need to be lowered with evaporative cooling. Also, the light intensity may be too great for the plants. During the summer, evaporative cooling, shade cloth, or paint may be necessary. Shade materials include roll-up screens of wood or aluminum, vinyl netting, and

paint.

Small package evaporative coolers have a fan and evaporative pad in one box to evaporate water, which cools air and increases humidity. Heat is removed from the air to change water from liquid to a vapor. Moist, cooler air enters the greenhouse while heated air passes out through roof vents or exhaust louvers. The evaporative cooler works best when the humidity of the outside air is low. The system can be used without water evaporation to provide the ventilation of the greenhouse. Size the evaporative cooler capacity at 1.0 to 1.5 times the volume of the greenhouse. An alternative system, used in commercial greenhouses, places the pads on the air inlets at one end of the greenhouse and uses the exhaust fans at the other end of the greenhouse to pull the air through the house.

Controllers/AutomationAutomatic control is essential to maintain a reasonable environment in the greenhouse. On a winter day with varying amounts of sunlight and clouds, the temperature can fluctuate greatly; close supervision would be required if a manual ventilation system were in use. Therefore, unless close monitoring is possible, both hobbyists and commercial operators should have automated systems with thermostats or other sensors.

Thermostats can be used to control individual units, or a central controller with one temperature sensor can be used. In either case, the sensor or sensors should be shaded from the sun, located about plant height away from the sidewalls, and have constant airflow over them. An aspirated box is suggested; the box houses each sensor and has a small fan that moves greenhouse air through the box and over the sensor (Figure 5). The box should be painted white so it will reflect solar heat and allow accurate readings of the air temperature.

Watering Systems

A water supply is essential. Hand watering is acceptable for most greenhouse crops if someone is available when the task needs to be done; however, many hobbyists work away from home during the day. A variety of automatic watering systems is available to help to do

the task over short periods of time. Bear in mind, the small greenhouse is likely to have a variety of plant materials, containers, and soil mixes that need different amounts of water.

Time clocks or mechanical evaporation sensors can be used to control automatic watering systems. Mist sprays can be used to create humidity or to moisten seedlings. Watering kits can be obtained to water plants in flats, benches, or pots.

CO2 and Light

Carbon dioxide (CO2) and light are essential for plant growth. As the sun rises in the morning to provide light, the plants begin to produce food energy (photosynthesis). The level of CO2

drops in the greenhouse as it is used by the plants. Ventilation replenishes the CO2 in the greenhouse. Because CO2 and light complement each other, electric lighting combined with CO2 injection are used to increase yields of vegetable and flowering crops. Bottled CO2, dry ice, and combustion of sulfur-free fuels can be used as CO2 sources. Commercial greenhouses use such methods.

Alternative Growing Structures

A greenhouse is not always needed for growing plants. Plants can be germinated in one's home in a warm place under fluorescent lamps. The lamps must be close together and not far above the plants.

A cold frame or hotbed can be used outdoors to continue the growth of young seedlings until the weather allows planting in a garden. A hotbed is similar to the cold frame, but it has a source of heat to maintain proper temperatures.

How About a PVC Greenhouse?Have you ever thought about a PVC greenhouse? I've heard about rebar and PVC greenhouses, but never thought about building one almost entirely out of PVC. What a great idea for frugal living and vegetable gardening.

I'm here to tell you that it is possible, and you can do it for less than you might think possible.

The construction techiques are basic, and it seems to require few if any specialized tools and fasteners. This is a do it yourself greenhouse if I ever saw one.

Jeremy and Wanda Manley were gracious enough to allow me to visit with them about their 17 by 32 foot greenhouse made from PVC. It was built in the spring of 2008, and they have had lots of success with it.

Located just southeast of Cheyenne, I know these folks see much the same windy weather that we do here northwest of town. The structure seems plenty sturdy to hold up in the wind, and I can tell you that it gets plenty warm inside too.

Let's dive in now and learn about this greenhouse structure made primarily from PVC. I'll try to provide sufficient information so you can make a determination if this might be right for

you. I think it might be a good design for a beginner, as it certainly doesn't look technically challenging.

The basic design of the structure is similar to what's known as a Gothic Arch. It isn't the rounded shape of the quonset hut, nor does it have straight sides and sharp angles like one would expect from a garage or shed.

I rather like the shape of the structure. It provides good room overhead without being wasteful, and it makes good use of the side walls. They don't go straight up, but they

don't curve in much either to where they might interfere with the gardener.

The primary materials are 2 inch PVC tubing and fittings. These materials should be readily available at your home improvement store. I understand that the Manley's built their structure out of 20 foot long pipe. This was important because the walls of the PVC greenhouse are made from 5 foot sections, and the rafters are made from 7.5 foot sections. It makes the construction work out well with little wasted material.

The PVC greenhouse is constructed mostly of PVC, with some wood elements. Sole plates and purlins are made from painted wood, and are mounted on the outside of the PVC piping. Painted wood lath is also used to hold the greenhouse film to the structure as shown to the right.

You'll note on the left that the ridge piece is 3/4 inch PVC mounted on the inside of the PVC piping, using conduit clamps that screw into the 2 inch PVC ribs. It also doubles as a header for overhead sprinklers or misting nozzles.

The nice thing about this arrangement is that when you shut down the water system for the season, the positioning of the lines overhead promotes draining to prevent freeze damage.

When you build your PVC greenhouse, even if you aren't going to use overhead watering, it's a good idea to have some sort of ridge piece to keep the ribs from wiggling and rubbing on the poly film.

There are 3/4 inch PVC water lines that run alongside of the purlins on both sides of the structure. These are headers for water lines that have spigots and hoses attached. If you would rather hand water, this is a good way to do it.

This PVC greenhouse also incorporates roll-up sides. A long PVC tube with a homemade crank is positioned on either side of the structure and attached with wood lath to the clear film used for glazing. After removing the weights that hold down the ends of the poly film, the sides can be rolled up to help vent the heat of the summer.

Ends and doors are made from wood, and the ends are anchored into the ground as a precaution against the winds we are famous for. Idaho is famous for potatoes, and we're famous for wind.

The sole plate of the PVC greenhouse is attached to the ends of the ribs, and then the sole plate is anchored into the ground as well. See photo on the right.

Earth anchors are rebar pounded about 2 feet deep. The above earth portion is bent into the shape of a hook to grab the sole plate.

External anchors as used for fastening rope that keeps the poly from picking up off the structure in high winds. If lath is used to secure the poly to perhaps every other rafter, and you use woven poly, you probably won't need to use rope to secure the top. If you do use rope, be sure that you attach some wooden guide piece to avoid damage to the poly as shown in the photo below left.

The amazing part of this structure is that it has no cross bracing on the walls. Usually a cross brace is necessary to

keep the structure from swaying lengthwise. The way cross braces are avoided with this PVC greenhouse is by using two screws, spaced far apart, to fasten the purlins to the sides of the building.

Spacing the screws farther apart provides a little "shear wall" effect on each of the ribs, and this is enough to keep this do it yourself greenhouse from swaying back and forth.

The photo above left shows the wooden purlin on the outside of the PVC piping, but inside the poly covering. The photo lower left shows how the purlin is spliced together to span this 32 foot long structure.

While I'm at it, I should mention that the fasteners for this project are almost exclusively drywall screws. The

PVC is soft enough that the screws penetrate it easily.

Care must be taken not to over-tighten the screws that bite into the PVC as this will risk stripping through the soft plastic material and making a weak connection.

The poly covering on the structure is UV protected greenhouse film. It is held in place at the purlins with painted lath that is screwed through the poly and into the purlins. The same approach is used at the bottom of the end, but not the sides (since they roll up). The poly at the top of each end is also secured in a similar manner, except instead of wood purlins, the lath and film are screwed into the end rafters.

The photo to the right shows how the lath on the outside of the ends is screwed through the poly film and secured into the 2 by 4 on the inside of the end walls. Nothing fancy, but it works just fine, and that's what you want with your PVC greenhouse - effectiveness at a low cost.

The poly film at the ends of the sides overlaps the ends a bit so it can be wrapped around the corner of the end wall and held in place to provide a seal for the greenhouse. The seal can't be secured much because it needs to allow the sides to roll up. This will naturally makes the PVC greenhouse a little "leaky", but it shouldn't make any difference at all in its performance, especially if you're not going to heat it.

Note: I suggest not heating any greenhouse unless you have double walls on all sides. Without double wall glazing, you'll have poor insulation, and you'll just end up tossing your money away.

Another part of this project involved making raised beds. Of course, something like this is optional, but I find raised beds to be a nice feature for organizing plants and more convenient gardening.

The photo to the left shows a raised bed right and left, and one on the far side of the PVC greenhouse. There was also a very nice work bench constructed of 2 by 4s with a hardware cloth (hail screen) top that would be ideal for a garden work bench. Dirt and water fall through the metal screening, so the bench top stays clear

of debris. What a great idea!I certainly appreciate Jeremy and Wanda letting me poke around, ask questions and take pictures of their greenhouse. It's a great way to start with greenhouse gardening, and it certainly is an inexpensive way to go.

You might get some of that purple primer and glue on your hands, but that beats splinters and sore thumbs from nailing up a wooden structure, and metal cuts and filings associated with a metal structure. I think building a PVC greenhouse will be far less challenging than other methods, especially if you are a beginner.

I understand that these structures can last quite a while. The longest lasting one I have heard of is 8 years, and that is impressive for plastic pipe that costs about 65 cents a foot.

Background and credit is in order here. This particular PVC greenhouse idea is the brainchild of Del Jimenez of New Mexico State University. Del is an energetic and knowledgeable man who is busy helping farmers and gardeners get the most from their efforts using organic means.

He put on a program for the Cheyenne Master Gardeners Club in May of 2008. I attended the lecture portion of the workshop. As part of his visit, he orchestrated the construction of this PVC greenhouse with the help of more than a dozen members of the club. It required a good two day effort as well.

For pictures of the greenhouse under construction, estimated costs and material data, and instructions for assembly, see: the program summary from the Laramie County Master Gardeners.

As with any project, building a PVC greenhouse goes quickly and more smoothly when you have lots of help, and everything is well organized from the start.

If part of your plan for frugal living is a do it yourself greenhouse, then this might be a low cost solution for you.

Double-wall greenhouse with flexible film walls

United States Patent 4274234

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A double-wall greenhouse with flexible plastic walls is disclosed. The side walls and roof of the greenhouse form an integral tunnel-like shell about an unobstructed internal space. Opposite ends of the shell are closed by end panels. The inner and outer surfaces of the shell are formed by parallel inner and outer flexible plastic glazings which enclose the supporting framework of the shell. Similarly, each end panel has inner and outer flexible plastic glazings enclosing its supporting framework.

The greenhouse can be built in any desired length simply by increasing the number of segments forming the shell. One segment includes two spaced-apart, parallel, upright archlike structural members whose lower ends are secured to opposite parallel sills. A sheet of plastic glazing extends along uninterrupted inner surfaces of the structural members from one sill member to the other. It is secured to the outer surfaces along its edges and ends and uniformly stretched between the members. The inner glazing is attached in similar fashion to the inner surfaces of the arch members and sill members. The edges of the glazings are secured by continuous glazing strips which are inserted, together with a margin of the glazings, into continuous channels extending along the inner and outer surfaces of the structural members and the sill members. Each has two parallel channels on its inner and outer surfaces for securing glazing sheets of adjacent modules.

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US Patent References: Frame structureHerbst et al. - August, 1979 - 4164105

Modular green house constructionSchwartz - November, 1977 - 4057941

Attaching means for members at an angle to one anotherCole - April, 1976 - 3950915

PLASTIC COVERED BUILDING STRUCTURESGahler - August, 1974 - 3830033

STRUCTURAL MEMBRANE ATTACHMENT TO AN ARCHHuddle - May, 1974 - 3811454

Inventors:

Abell, Irwin R. (Portland, OR)

Application Number:

06/014169

Publication Date:

06/23/1981

Filing Date:

02/22/1979

Export Citation:

Click for automatic bibliography generation

Assignee:

Hartwig-Hartoglass, Inc. (Woodstock, IL)

Primary Class:

52/63

Other Classes:

52/93.1, 52/222, 52/273, D25/22

International Classes:

A01G9/14; E04H15/34; E04H15/64; A01G9/14; E04H15/32; E04H15/34; (IPC1-7): E04B1/12

Field of Search:

52/63, 52/222, 52/273, 52/86, 52/586, 52/93, 47/17, 160/392, 160/395, 160/394, 160/391, 160/397

View Patent Images:

Download PDF 4274234 PDF help

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US Patent References:

3165110

Building constructionJanuary, 1965

Brooks

52/222

2986150

Means for mounting thin, flexible membranes

May, 1961Torian

47/17

2827138

Portable building constructionMarch, 1954

Ray, Jr.

47/17

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Foreign References:

CA639500

April, 1962

52/222

Primary Examiner:

Friedman, Carl D.

Attorney, Agent or Firm:

Klarquist, Sparkman, Campbell, Leigh, Whinston & Dellett

Claims:

I claim:

1. In a double-wall building structure with flexible walls, a structural member comprising:

two upright portions having lower ends for positioning along opposite sides of said structure to support sidewalls thereof;

a connecting portion extending between said upright portions opposite said lower ends to support a roof of said structure;

the structural member having an uninterrupted inner surface beginning at the lower end of one of said upright portions, extending along the lower side of said connecting portion, and continuing along the other of said upright portions to the lower end thereof;

the structural member also having an outer surface opposite said inner surface and extending along outer and upper sides of said member; and

glazing fastener means along said inner and outer surfaces for attaching said flexible walls along an unbroken line to each of the inner and outer surfaces of said member;

the structural member including at least two separable submembers joined together by lap joints;

the glazing fastener means including channel means and glazing strip means;

the channel means defining a pair of parallel channels on each of the inner and outer surfaces of the structural member, one of said channels extending along each side of said lap joint to continue said unbroken line from one submember to another;

the glazing strip means including an insert flange for insertion into the channel together with a margin of said flexible walls, the insert flange having ribs such that it can be progressively inserted into said channel to stretch said flexible walls in a two-stage operation to impart tension in said inner and outer walls to rigidify said structure.

2. A structural member according to claim 1, in which said structural member is symmetrical about a centerline between said upright portions;

said structural member being separable into at least two substantially identical submembers.

3. A structural member according to claim 2, in which said structural member includes two submembers separable about said centerline.

4. A structural member according to claim 1, in which each submember has a vertical stud member defining said upright portion and a rafter member defining a portion of said connecting portion, the rafter member being joined to the stud member at an angle of approximately 60° from the vertical plane.

5. A structural member according to claim 1, in which said inner and outer surfaces define, in cross-section, opposite sides of a rectangle, said channels being formed directly in said surfaces, the spacing between said surfaces being greater than their width.

6. In a double-wall building structure with flexible walls, a structural member comprising:

two upright portions having lower ends for positioning along opposite sides of said structure to support sidewalls thereof;

a connecting portion extending between said upright portions opposite said lower ends to support a roof of said structure;

the structural member having an uninterrupted inner surface beginning at the lower end of one of said upright portions, extending along the lower side of said connecting portion, and continuing along the other of said upright portions to the lower end thereof;

the structural member also having an outer surface opposite said inner surface and extending along outer and upper sides of said member; and

glazing fastener means along said inner and outer surfaces for attaching said flexible walls along an unbroken line to said member;

said glazing fastener means including a channel extending lengthwise along said surfaces and glazing strip means for insertion into said channel together with a margin of said walls;

said channel having two parallel channel walls, the depth of said channel being approximately 2.5 times the distance between said channel walls, and

said glazing strip including an insert flange and two external flanges positioned to define a generally T-shaped cross-section; the insert flange having two symmetrically-positioned ribs extending lengthwise along each side, the thickness of the insert flange at said ribs being approximately equal to the width of said channel, said insert flange extending nearly to the bottom of said channel.

7. A double-wall building structure with flexible walls, comprising:

rectangular sill means for supporting said structure, each side of said sill means having parallel inner and outer surfaces;

at least two upright, parallel structural members defining a roof and walls in said structure, said members being spaced part along said sill means and having their lower ends secured to two opposite sides of said sill means, said structural members having lengthwise parallel inner and outer surfaces contiguous with the inner and outer surfaces, respectively, of said two sides of said sill means;

a first flexible film wall having margins extending along said outer surfaces and a second flexible film wall having margins extending along said inner surfaces, said walls being stretched from side-to-side between said members and extending end-to-end from one side of said sill means to the opposite side of said sill means to enclose an airspace therebetween; and

glazing fastener means for attaching said flexible walls along said inner and outer surfaces,

each of said fastener means including a channel and a glazing strip having an insert portion adapted for insertion into said channel together with a margin of one of said flexible walls, said channel being oriented so that the direction of insertion of said insert portion is approximately normal to said flexible walls,

said channel and insert portion having lengths in said insertion direction of at least twice their respective widths.

8. A double-wall building structure with flexible walls, comprising:

rectangular sill means for supporting said structure, each side of said sill means having parallel inner and outer surfaces;

at least two upright, parallel structural members defining a roof and walls in said structure, said members being spaced apart along said sill means and having their lower ends secured to two opposite sides of said sill means, said structural members having lengthwise parallel inner and outer surfaces contiguous with the inner and outer surfaces, respectively, of said two sides of said sill means;

a first flexible film wall having margins extending along said outer surfaces and a second flexible film wall having margins extending along said inner surfaces, said walls being stretched from side-to-side between said members and extending end-to-end from one side of said sill means to the opposite side of said sill means to enclose an airspace therebetween; and

glazing fastener means for attaching said flexible walls along said inner and outer surfaces including channel means and strip means;

said channel means including a channel extending along each of said inner and outer surfaces, the channels of said structural members extending in an unbroken line along said members from one lower end to the other lower end to meet the channels of said sill means;

said glazing strip means including an insert portion adapted for insertion into said channel together with a margin of one of said walls;

the inner and outer surfaces of said structural members defining, in cross-section, opposite sides of a rectangle;

said channel means including two parallel channels in each of the inner and outer surfaces of said members,

the channels having a depth which is between two and three times their width; and

said insert portion being a flange having parallel opposite sides and two parallel, lengthwise-extending ribs on each side, said ribs being spaced apart and positioned symmetrically about a centerline between said sides.

9. A double-wall building comprising:

structure defining two side walls and a roof integrally connecting said side walls;

two end walls, at least one of which has a door frame defining a door opening therethrough; and

sill members supporting said walls, said sill members including parallel inner and outer surfaces;

said structure including:

multiple, substantially identical, parallel, upright structural members spaced along two of said sill members and having opposite lower ends connected thereto; each structural member being formed of thermally insulative material and having parallel opposite inner and outer surfaces in said side walls and roof, said surfaces extending uninterrupted between and meeting the inner and outer surfaces, respectively, of said two sill members;

two continuous sheets of flexible wall material extending from side to side between two of said structural members and from end to end between said two sill members; opposite margins of one sheet extending lengthwise along the inner surfaces of said structural members and opposite margins of the other sheet extending lengthwise along the outer surfaces of said two structural members;

each of said sheets being continuously attached along its margins to said surfaces and being stretched tightly therebetween;

said end walls each including:

a second upright structural member positioned in parallel abutting relationship along a side of an end one of said multiple members;

said second member and said door frame having inner and outer surfaces in planes normal to the inner and outer surfaces of said multiple members and meeting the inner and outer surfaces, respectively, of one of said sill members;

said second member being of the same general shape as said multiple members, but being sufficiently smaller that a first portion of its inner surface partially overlaps the side of the end one of said multiple members, and a second portion of its inner surface forms an inner corner with the inner surface of said end one of said multiple members; and

a continuous sheet of flexible wall material extending along each of the inner and outer surfaces of said end wall, said sheet being continuously attached along its margins to one of said surfaces and being stretched therealong.

10. A building according to claim 9, in which said structure includes bracing members extending between upper portions of two adjacent ones of said multiple structural members, said bracing members being enclosed between said two sheets

of flexible wall material.

11. A building according to claim 9, including a third end wall having a frame defining a door opening therethrough; said third end wall being positioned intermediate said two end walls and sandwiched in abutting relationship between two of said multiple structural members, thereby dividing said building into two compartments.

12. In a double-wall building structure with flexible walls, a structural member comprising:

two upright portions having lower ends for positioning along opposite sides of said structure to support sidewalls thereof;

a connecting portion extending between said upright portions opposite said lower ends to support a roof of said structure;

the structural member having an uninterrupted inner surface beginning at the lower end of one of said upright portions, extending along the lower side of said connecting portion, and continuing along the other of said upright portions to the lower end thereof;

the structural member also having an outer surface opposite said inner surface and extending along outer and upper sides of said member; and

glazing fastener means along said inner and outer surfaces for attaching said flexible walls along an unbroken line to said member;

the glazing fastener means including a channel and a glazing strip having an insert portion adapted for insertion into said channel together with a margin of one of said flexible walls, said channel being oriented so that the direction of insertion of said insert portion is approximately normal to said flexible walls;

said channel and insert portion having lengths in said insertion direction of at least twice their respective widths;

the insert portion being insertable to at least two different depths in said channel to stretch and hold said walls under an amount of tension which corresponds to the depth of insertion of said portion.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to my copending patent application, Ser. No. 014,149, filed concurrently herewith, for a Glazing Fastener for Mounting Either Rigid or Flexible Storm Windows.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to greenhouse construction, and more particularly to double-wall greenhouses having flexible plastic walls.

2. Description of the Prior Art

In the past greenhouses have used glass panes mounted in a metal framework. However, they are very expensive to build and operate and, thus, are only within the financial reach of commercial growers. Such greenhouses are also vulnerable to breakage and to formation of water condensation on the glass panes. Such condensation blocks the sunlight and drips from the window frames, causing damage to the plants. To reduce condensation and cut heating costs, greenhouses have been double glazed, but only at further increase in construction costs.

Such greenhouses are, therefore, very expensive for commercial growers, and far too expensive for the home greenhouse market. It would be preferable to have a greenhouse which is compact, constructed of inexpensive materials, easily assembled, and inexpensive to operate. More specifically, a greenhouse should have a low roofline yet provide adequate standing head room. It should be constructed of inexpensive insulative materials, and include a double glazing. Such glazing should be relatively invulnerable to breakage, should be inexpensive, and should be easily installed.

Several attempts have been made at improving greenhouses and bringing down their costs. One design uses a wooden, rather than metal frame, and substitutes transparent plastic panes for conventional glass. However, such a greenhouse is still expensive to construct. Plastic panes cost nearly as much as glass, and substantial labor and materals is required to assemble the frame and mount the individual panes.

In another variation, sheets of corrugated fiberglass are applied to the roof and walls of the wooden frame. This creates several other problems. The corrugated material is hard to seal along its edges and is difficult to fit around the internal joists and corners of the frame to obtain adequate double-wall construction. In addition, fiberglass material lacks adequate transparency for many greenhouse applications.

In a further variation, sheets of flexible plastic film are attached to the frame by lathe strips nailed to the frame members. However, the plastic film is easily torn by the nails and by corners at the joints in the frame. It is difficult to seal the plastic sheets adequately against the wooden frame. Internal bracing, such as roof joists and corners make it very difficult to double glaze such greenhouses. Finally, such internal bracing necessitates a high roofline on the greenhouse in order to obtain sufficient standing head room. It also interferes with sunlight reaching the plants within the greenhouse.

It has also proven difficult to stretch the plastic film sufficiently to obtain a wrinkle free fit. Various types of framing strips and bead strips have been suggested for securing the edges of film along opposite sides of a window opening. Framing strips commonly have a groove or channel for receiving a complementary glazing or bead strip to secure a margin of the flexible film within the channel. Such an arrangement is shown in my own prior patent, U.S. Pat. No. 3,991,806 and patents cited therein. However, such fasteners either fail to stretch the fabric

sufficiently to remove the wrinkles when assembled, or are unable to hold the film under sufficient tension without the bead strips pulling from their grooves.

A second greenhouse design uses an inflated structure of transparent plastic film. Such a greenhouse has no frame and therefore avoids the head room and shade problems, but it cannot be double glazed. Furthermore, such a greenhouse is expensive to keep inflated and vulnerable to damage.

A third design employs bowed aluminum arches over which plastic film is stretched. In this design it has been very difficult to obtain an adequate air seal at the bottom where the plastic meets the ground and around the ends. More importantly, such a design cannot be double glazed since there was no way of attaching a second wall to the inside of the aluminum bows.

SUMMARY OF THE INVENTION

From the foregoing, there remains a need for a greenhouse which is inexpensive to build and to operate, is compact yet provides sufficient standing head room, is not overly vulnerable to damage, avoids problems of moisture condensation and dripping, and does not unduly shade plants inside the structure. Such a greenhouse should be constructed of a small number of parts to reduce costs of materials and labor for assembly. The design of such a greenhouse should also be readily expandable to a variety of sizes using the same kinds of parts used in the basic design. These are, therefore, the principal objects of the invention.

The greenhouse of the invention employs a thermally insulative frame that is especially adapted for attaching continuous sheets of flexible glazing material along inner and outer surfaces of the frame to form double walls.

The frame features multiple parallel, upright structural members spaced apart along two preferably parallel sill members. The inner and outer surfaces of each structural member parallel those of the other members and are contiguous with the inner and outer surfaces, respectively, of the sill members. The inner and outer surfaces of such members are unobstructed by braces or joists so that a rectangular sheet of flexible plastic film can extend along such surfaces without interference.

One side margin of a first sheet of flexible film extends lengthwise along the inner surface of a first structural member and the opposite side margin extends along the inner surface of a second structural member. The end margins extend along the inner surfaces of the sill members between the first and second structural members. Similarly, the margins of a second sheet extend along the outer surfaces of the two structural members and the portions of the sill members between them.

Thus, the inner and outer walls enclose an insulative airspace whose thickness corresponds to the spacing between the inner and outer surfaces. Such walls are preferably parallel and spaced between two inches and four inches apart.

The margins of the sheets forming the walls are attached continuously along the inner and outer surfaces by glazing fastener means. Glazing fastener means includes a channel means defining a channel along such surfaces and a glazing strip means having a portion adapted for insertion into the channel together with the margin of a glazing sheet.

Each structural member features two spaced apart upright portions for supporting the building's side walls and a connecting portion extending between the upright portions for supporting its roof. The member is preferably symmetrical about a centerline between the upright portions and can be separable into at least two submembers. Such submembers can be substantially identical halves of the structural member, or individual rafters and stud members.

In another aspect of the invention the inner and outer surfaces of the structural member define, in cross-section, opposite sides of a rectangle. The width of the inner and outer surfaces is preferably narrower than the distance between them.

The channels can be formed directly in the parallel inner and outer surfaces thus defined. The glazing strip means can be a strip having a T-shaped cross-section and including an insert flange adapted for fitting snugly within the channel. The channel is preferably at least twice as deep as its width, the insert flange extending nearly to the bottom of the channel.

The insert flange can include two parallel ribs extending lengthwise along each side, the ribs being preferably positioned symmetrically about a centerline between opposite sides of the flange. This arrangement permits the flexible plastic to be stretched in two stages as the glazing strip is inserted all around to the depth of the first rib, and then pushed in to the depth of the second rib.

The end walls or panels, at least one having a door opening therethrough, have a peripheral structural member whose general shape is the same as that of the afore-mentioned structural members which form the side walls and roof of the building. However, it is slightly smaller so that it can be positioned in close parallel abutting relationship against an end one of the first-mentioned structural members to obtain a tight airseal at the corner of the building and yet have an unobstructed inner face for attaching a margin of the inner wall at the corner.

A third end wall, preferably with a door opening therethrough, can be placed across the middle of the building with one of the first-mentioned structural members abutting it on each side. Thus the building is easily divided into compartments which are thermally insulated from one another.

The frame can also have bracing extending between the structural members. Such bracing, which is contained entirely within the airspace between the inner and outer walls, cooperates with the stretched flexible film to further rigidify the building. Thus, the use of joists or other braces across the internal space of the building can be eliminated.

These and other objects, advantages and features will become more apparent from the following detailed description of a preferred embodiment of the invention which proceed with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the frame of a greenhouse according to the present invention, with fragmentary portions of the plastic walls in position on the shell and with the channels for the margins of the remaining portions of the plastic walls omitted for clarity.

FIG. 2 is a fragmentary horizontal sectional view taken along line 2--2 in FIG. 1.

FIG. 3 is a fragmentary vertical sectional view taken long line 3--3 in FIG. 1 with the plastic walls in place.

FIG. 4 is a cross-sectional view taken along line 4--4 in FIG. 3.

FIG. 5 is an enlarged cross-sectional view of a channel and glazing strip of the type employed in the present invention for securing the flexible film walls to the frame.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a double wall building structure with flexible film walls, such as a greenhouse, has a frame 10 supporting inner and outer flexible walls 12, 14. The walls enclose the frame and an insulative layer of air 16. The frame is preferably made of redwood 2"×4" lumber, although other insulative materials, such as molded low density plastic will suffice. The walls are preferably made of vinyl plastic or mylar film.

In general, the structure is rectangular with a pitched roof. It has two opposed rectangular side wall panels 20, 22 and two opposed pentagonal end wall panels 24, 26. The pitched roof is defined by two rectangular roof panels 28, 30. The lower edges of the side panels 20, 22 are defined by two parallel opposed sill members 32, 34, respectively. Similarly, the lower edges of the end panels 26, 28 are defined by parallel sill members 36, 38, respectively.

The side wall panels and roof panels form an integral tunnel-like shell, opposite ends of which are closed by the end panels. The internal space thus defined is unobstructed by joists or other bracing structure. Referring to FIG. 3, the inner surface of the shell is defined by the flexible inner wall 12. Similarly, the outer surface of the shell is defined by the outer flexible wall 14. In the same way the inner and outer surfaces of the end panels 24, 26 are defined by inner and outer walls 112, 114. However, end panel 26 also has a centrally positioned door opening therethrough and a door 40 within the opening (FIGS. 1 and 2).

The greenhouse of FIG. 1 includes two segments, indicated generally by reference numerals 42 and 44. Segment 44 extends from structural member 46 adjacent to end panel 24, to structural member 48, which is positioned equidistant between the end panels. Similarly, segment 42 extends from structural member 48 to structural member 50, which is adjacent to end panel 26. Structural members 46, 48 and 50 are identical and symmetrical about a centerline 51 (FIG. 3) between the wall panels 20 and 22.

Each structural member has two upright portions consisting of studs 52, 54, and a roof portion, consisting of rafters 56, 58, extending between the upright portions. Referring to FIG. 3, the lower end of vertical stud 52 is connected to horizontal sill member 34. Rafter 56 is connected to the upper end of stud 52 and extends at an angle, for example, approximately 60°, from the vertical in the direction of stud member 54 (not shown). Rafter 56 meets rafter 58 at the centerline of the structure.

Studs 52 and 54 are identical. Similarly, rafters 56 and 58 are identical. Stud 54 has its lower end cut off square and its upper end cut at an angle from the vertical, for example, about 60°. Opposite ends of rafter 56 are cut at the same angle so that a side view of rafter 56 defines a trapezoid. Refering to FIG. 4, the upper ends of the studs and the ends of the rafters are connected at lap joints held together by a male-female double headed screw 60, and further reinforced by the use of wood glue.

In forming the preferred type of lap joint, the upper end of each stud is sawn in a plane normal to the wall panel and intermediate the sides of the stud to a depth corresponding to the width of the rafter which is to be connected to the stud. A second cut is then made normal to the first cut and at an angle, for example, a 60° angle, from the vertical, to remove a parallelogram-shaped piece of wood from the end of the stud. A similar operation is performed on each end of rafters 56, 58 and on stud 54.

Referring to FIG. 3, it can be seen that the studs have an inner surface 62 and an outer surface 64. At the lower end of the stud where it meets the sill member, its inner surface 62 is coplanar with the inner surface 70 of the sill member. Similarly, the outer surface 64 of the stud is coplanar with the outer surface 72 of the sill member. At the upper end of the stud inner surface 62 intersects the inner surface 66 of the rafter at an angle, for example, 60°. Similarly, outer surface 64 intersects outer surface 68 at the same angle. Surface 68 includes the upper face of rafter 56 and the end of stud 52.

Thus, the inner surface of the structural member extends continuously from an inner surface of the sill member along the inner surface of the upright portion, along the lower surface of the roof portion, continuing down along the inner surface of the other upright portion and ending at the inner surface of the opposite sill member. Similarly, the outer surface of the structural member extends continuously from the outer surface of the sill member, upwardly along the outer surface of the upright portion, along the upper sides of the roof portion and downwardly along the outer surface of the opposite upright portion to meet the outer surface of the opposite sill member. The sill member's inner surface 70 extends laterally along each sill member, such surfaces intersecting at the building's corners. The outer surfaces 72 also extend along each sill member, but need not meet at the corners.

Referring to FIG. 5, a flexible glazing fastener means 74 includes a channel 76 and a glazing strip 78. Such glazing fastener means are described in detail in my above referenced copending application for patent, which is incorporated by reference herein. In general, the glazing strip includes an insert flange 80 having two pairs of ribs 82, 84 along each side.

The insert flange is designed to stretch the flexible glazing film as the flange is pushed into the channel. One purpose of the ribs on each side of the flange is to emable the film to be progressively stretched in a two stage operation. Thus, the flange is inserted into the channel together with the film in the first stage and pressed in to the extent of the first pair of ribs 82 where it remains while the rest of the film is being secured around its other margins. Once the first stage has been completed around all of the margins of the film, the glazing strip is pressed in the rest of the way, thereby further stretching the film. The film is compressed tightly between the channel walls and the ribs on each side of the insert flange, and is thereby securely held in place.

Referring to FIGS. 2 and 4, channels of the type shown in FIG. 5 are provided on the inner and outer surfaces of the structural members. In member 48 there are two parallel channels extending along the inner surfaces and two more parallel channels extending along the outer surfaces. A channel also extends laterally along each of the inner and outer surfaces of the sill members and intersects the channels extending downward from the structural members.

In FIG. 2, member 50 has a single channel extending along its inner and outer surfaces. In practice, two such channels are likely to be provided as in member 48, even though one channel

in each surface would be unused, so that a single configuration of structural member can be used throughout the greenhouse.

Two continuous rectangular sheets of flexible glazing material form the inner and outer walls 12, 14 of each segment 42, 44. Referring to FIG. 3, the end margins of each sheet are attached to inner and outer surfaces 70, 72 of the sill members by glazing fasteners 74. The sheet forming inner wall 12 in segment 42 is stretched between structural members 48 and 50 and is continuously secured along its side margins to the inner surfaces 62, 64 of each member 48, 52 by fasteners 74. Similarly, the sheet forming outer wall 14 is stretched between members 48 and 50 secured to the outer surfaces 64, 68 of each member 48, 58. Segment 44 is likewise provided with inner and outer walls.

Referring to FIG. 1, ridge poles 86 extend horizontally between the peaks of the structural members. Plate members 88 extend horizontally between the structural members at the joints formed between the studs and the raftes. The plate members and the ridge poles are all of the same length, which length is equal to the spacing between the structural members. Thus, poles 86 and plate members 88 maintain the parallel relationship between the structural members 46, 48, 50 and support portions of the outer wall 14 along their corners.

Diagonal braces 90 extend at 45° angles from the sill members 32, 34, within the airspace 16, to the sides of structural members 46 and 50. Such braces maintain the perpendicular relationship of the structural members to the sill members.

The poles and plate members are attached to the structural members by angle plates 89, nailed to the members on one side of plate 89 and to the poles and plate members on the other side.

The pentagonal end wall panels 24 and 26 include structural members 92 and 94, respectively, closely abutting members 46 and 50. members 92 and 94 are similar in their overall construction to members 46, 48 and 50 but are slightly smaller.

More specifically, structural members 92 and 94 have vertical studs 96, 98 which are shorter than studs 52, 54, and rafters 100, 102 which are slightly shorter than rafters 56, 58. Referring to FIG. 2, stud 96 has an inner side face 104 abutting and partially overlapping side face 106 of structural member 50. Face 108 of stud 96 is spaced inwardly of the inner surface 62. This spatial relationship is maintained uniformly along members 50, 94 and also exemplifies the relationship of members 46, 96 at the opposite end of the building, as can be seen by reference to FIG. 1.

Such relationship increases the stability of the structure and provides attachment surfaces for the flexible walls 112 and 114 about airspace 116 in the end panels. By bolting members 92, 94 to members 46, 50 and glueing their overlapping faces 104 and 106 together, a tight seal is obtained along the corners of the structure.

In end panel 26 two spaced-apart vertical studs 118, 120 extending from sill member 38 to rafters 100, 102 and a horizontal head member 122 extending between rafters 100 and 102 to frame door 40. Horizontal braces 124, 126 extend from the door frame to studs 96, 98, to further reinforce the end panel. The door also has a vent 127.

End wall panel 24 has two spaced-apart vertical studs 128, 130 extending from sill member 36 to rafters 100, 102 and a horizontal brace 132 extends between them to support a solid panel 134, which also has a vent 136. Vents 127, 136 each include a small hinged door.

It is sometimes desirable to divide a greenhouse into multiple compartments which can be kept at different temperatures. Referring to FIG. 2, an additional end panel 138 (shown in phantom lines) is inserted into the greenhouse between members 48 and 50, increasing its length to three segments and dividing the building crosswise into two compartments.

Panel 138 is sandwiched between two structural members 50a and 50b, abutting such members in the manner described above for end panel 26. Panel 138 is substantially identical to panel 26, and members 50a, and 50b are substantially identical to member 50. It is apparent that such a building may contain any desired number of segments with or without additional panels 138.

Numerous variations of structure are possible within the spirit of the invention. For example, arched structural members can be substituted for the angular structural members 50, 94. Such arched members can be molded plastic, fiberglass or laminated wood, and can be made in one piece, or in two identical halves. It is also possible for the combined members 50, 94 to be formed in one piece.

Having illustrated and described a preferred embodiment of the invention, it should be apparent to those skilled in the art that the invention may be modified in arrangement and detail. I claim as my invention all such modifications as come within the true spirit and scope of the following claims.

Greenhouse Kit - build a low tunnelAre you considering a greenhouse kit to save yourself some time and effort? Well, here's a story of a 14 by 20 foot low tunnel greenhouse that neighbors of mine built from a kit. It is a nice design and appears to be very effective.

If your plan for frugal living includes greenhouse vegetables, but you don't want to fabricate something yourself, a kit may be the answer. You still have to put it together, but you don't have to fabricate anything, so it can save you some time and effort.

Let's meet Catherine and Martin Wissner, some really nice folks that live just a bit southeast of Cheyenne. They raise sheep, turkeys, llamas and lots of vegetables. They have a low tunnel and a high tunnel, and plenty of open air garden space where they have quite a bounty.

For two people, their operation is very impressive indeed. I get tired just thinking about all they have going. They were kind enough to invite me out to their nice comfortable place in the country where the large shade trees remind me of the traditional homestead farm.

The greenhouses remind me of their eye toward technology to help create self-sufficiency, and that's a good way to be.

Let's look at their low tunnel which is really a greenhouse by any other name. I suppose the difference is more in the connotation of the word "greenhouse". It usually suggests all the vents and fans and humidity controls of a gardening structure.

The Wissners deliberately stayed away from all of that to reduce costs and keep it simple. A good idea if you ask me. Vents and fans are expensive to buy and can be a considerable expense to operate. Heaters can too. When someone rolls their eyes when talking about heating their greenhouse with propane, you don't have to ask them for more information - you've got the picture of great big dollar signs.

This low tunnel greenhouse kit is of a hoop house design as shown on the left, and it's about 9 feet tall in the center.

It is simply multiple sets of rigid metal pipes bent in an arch that make the ribs (rafters or bows) for the structure. Think of a rib cage, and you have a good idea of why it has that shape and just how strong it is.

Each rib of the greenhouse kit consists of three separate pipes. The pipes are fastened together with heavy duty sheet metal screws. There is a ridge piece running down the center of the upper most portion of the structure, and two purlins on each side.

The lower purlins are made from 2 by 4s about 4 feet off the ground on each side of the structure. Carriage bolts

hold the purlins to the "ribs".

The ridge piece is connected to the "ribs" with a special fastener that bands the pipes in place without the need to drill holes.

The pipes for this greenhouse kit are 14 gauge, and that means they are very rigid and strong. You won't be bending these accidentally. The ribs are spaced 4 feet apart.

Note: a spacing of 4 feet is typical for a greenhouse kit. You can add more ribs if you like and create closer spacing between ribs or a longer low tunnel than what the regular greenhouse kit will normally provide.

The covering for the low tunnel is a double layer of clear poly film with a blower used to inflate between the layers for added

insulation. The blower, shown on the right, takes in air from outside through a flexible tube and blows it between the two layers of poly.

"Wiggle wire" is used to secure the double layers of poly to the end pieces. The "wiggle wire" uses a metal channel into which the plastic covering is inserted. The wire is then placed inside the channel and it presses the plastic against the inside of the channel to hold it in place.

The photo below shows the "wiggle wire" used to hold the poly covering in place along the bottom edge of the purlin. It is also used to hold the edges of the poly in place at the ends of the structure.

For this greenhouse kit, the Wissners selected ends made from twin wall polycarbonate panels with square metal tubing and metal channels to hold it in place. The panels are rigid and transmit light very well.

The photo to the right shows how the upright members of the end walls are connected to the "ribs" at the far ends of the structure. Also note how the metal purlin is attached to the end walls by clamping onto the "ribs" at the far ends of the structure.

Note: this structure is made with 4 purlins and a ridge piece. Two wooden purlins are located about 4 feet off the ground, a metal ridge piece is in the top center of the building, and two metal purlins are located one on each side about midway between the wooden purlin and the ridge piece.

A mechanism that rolls up the sides is attached to both sides of the low tunnel to allow the sides to roll up for ventilation. It is amazing how the mechanism rolls up the sides with ease.

The covering is secured on the underside of the purlins with "wiggle wire". This makes the upper shell of the covering immobile, but allows the lower portions to hang down to the ground but not secured to the building.

The portion that hangs from the purlin to the ground is attached on the far end to a long pipe. The pipe is attached to the roll up mechanism so it can be used to roll up the clear cover.

Nylon rope is woven from the purlin to the ground in a zig zag pattern to provide a type of "net" to help keep the loose portion of the clear covering from flapping around when it is in the rolled down position. A flapping portion of the poly cover will soon wear out and fail.

The photo to the right shows the nylon rope "net" that retains the rolling portion of the cover. Here the side is rolled up partway to allow for ventilation.

Ground posts are used to position the ribs in place, and then each rib is secured to the ground post with a fastener. The sides and ends of the structure that touch the ground are wood, and "high sides" are anchored to the "ribs" and ground stakes as shown in the photo lower left.

Earth anchors are used to pull the structure down onto its ground post foundation using turnbuckles. The earth anchor is simply a long metal rod with a auger tip that buries itself in the ground when it is twisted in a clockwise manner. Once in place, the only practical way to get it back out is to untwist in a counterclockwise manner.

In the photo to the left, just the "eye" of the earth anchor is shown above ground level. The rest of the anchor is buried securely underground.

The photo to the lower right shows an example earth anchor. The larger and taller the structure, the deeper the earth anchor should go. The low tunnel required 2 foot long earth anchors, one on each of the ends of the ribs.

Martin built an adapter to fit into a powerful drill, and he used that to install the anchors. Installing

the first one by hand with a metal rod was sufficient to motivate him to build a special tool to do the job with much greater ease.

With 12 anchors to install, the custom made tool and heavy duty drill were real labor savers. In addition, it allowed him to work in tight spaces once the ribs and side walls were in place.

Speaking of labor, the Wissners employed several laborers from a local labor shop to help assemble their greenhouse kit. Having extra hands is a big benefit when you are assembling something like this. With one hand holding this and one hand holding that, one can run out of hands quickly.

Having at least two others help you during assembly is a real benefit. One more wouldn't hurt either, even if they only help with getting tools and fasteners for others.

Multiple sets of hands are a must if your greenhouse kit assembly is going to be a pleasant experience.

I should note that items such as turnbuckles, earth anchors and wooden purlins and wooden high sides typically do not come as part of the greenhouse kit. You'll need to purchase things like this separately.

By the looks of the results shown on the left, the low tunnel greenhouse kit has earned its keep. If only I knew how to make Chiles Rellenos, I might have stuffed a few of those beauties in my

camera bag.

So, there you have it. A low tunnel that comes as a greenhouse kit with double poly covering, twin wall ends and roll up sides. No electricity, nothing automatic, but good simplicity that works well to provide great results.

Consider something like this as part of your frugal living plan for fresh and inexpensive vegetables. It will last for many years, and you can probably build it in a couple of days with a little help.

Low Cost Greenhouse Construction

Step by step directions on how to build your own low cost, high tunnel, greenhouse for fall and winter season extension.

By Tim Coolong, University of Kentucky Photo credits: Tim CoolongVisit: www.extension.orgSee also: High Tunnel Video Presentation

Tim Coolong is an assistant professor at the University of Kentucky. Dr. Coolong works primarily with small mixed vegetable farms around Kentucky. His research has focused on sustainable management for mixed vegetable production including irrigation management, new crops, and season extension.

High tunnel (hoop house) greenhouses are becoming increasingly popular for use by small farms who often market directly to consumers. Although they have proven to be economically advantageous to farmers who wish to capitalize on high prices obtained either early or late in the growing season, permanent high tunnel structures do represent a significant capital investment. The cost for a standard size tunnel, including plastic (two layers) and all the materials required for construction can range from $1.50-$2.50 per

square foot without labor and freight charges. This represents an initial investment of several thousand dollars, which is simply too much for some small farms. Although most growers are able to pay for their tunnels within a few growing seasons, others cannot justify the investment. For this reason, extension and research personnel at the University of Kentucky have been working on developing a low cost high tunnel covered with a single layer of plastic that can be assembled or moved in an afternoon.

This low cost high tunnel only provides about 3 oF in frost protection, compared to 7 oF for a double poly tunnel. This tunnel design has proven to withstand 60 mph winds with little damage in central and western KY. This tunnel will not withstand much more than a very light snow event (<1 inch), however it is not meant to be used through the winter in parts of the country that receive significant snowfall. The best time to use this tunnel is for a few months in early spring and mid-fall that receive low daily temperatures and mild frosts. Demonstrations in Central and Eastern KY have shown that growers can reach the market up to three-four weeks earlier with tomatoes grown in this tunnel than in the field. The added income from these early tomatoes more than offsets the initial costs.

Additional benefits from this type of design include the ability to make the tunnel as long as is necessary. Because much of the labor is in constructing the endwalls, there is not as much difference in labor costs for constructing a 300 foot long tunnel compared to a 100 foot long tunnel. Obviously materials costs are more, but it allows flexibility for the grower depending on market conditions. Another positive for organic growers in particular is the ability to easily disassemble the tunnel and move it from one location to another. One of the central tenets of organic agriculture is the idea of crop rotation. Unfortunately with some of the more permanent high tunnel structures proper rotation is difficult. Often growers find themselves growing the same crop in the same location for many years. Failure to rotate annual crops does not comply with organic requirements, and in many cases results in high levels of soil-borne diseases. Organic growers in particular have had to adapt to find creative ways to deal with these diseases, including grafting of resistant rootstocks, biofumigants, and soil solarization. Being able to quickly move a tunnel allows growers to easily rotate and avoids many of these problems. The following are step-by-step instructions on how to assemble this type of tunnel. This design is constantly being modified to find the most economical use of money and labor while still providing a sturdy useful structure. Below is a detailed outline on how to construct this tunnel.

Constructing the High Tunnel Greenhouse

In this tunnel we have already laid plastic in the field and transplanted. By assembling the tunnel over the already formed beds we can use traditional tractor mounted bedshapers and transplanters, saving the need for specialized equipment. Here anchors are made from one inch diameter pieces of steel pipe 24 inches in length with a single turn of auger flight welded to the end. The kleet is welded approxiametly 18 inches on the anchor.

These anchors are placed on eight foot centers the entire length of the tunnel. Genrally they are spaced 12 feet apart, which is enough to easily cover two beds made on six foot centers.

The anchors are then augured into the ground with a small hydraulic driven motor which can be hooked to a tractor. Anchors are driven into the ground so that the "hook" that is welded on the side is just at the soil level.

Then 1.5 inch schedule 40 pvc pipe is placed over the anchors. Typically pipe can be purchased in 20 foot lengths. A 20 foot pipe will form a tunnel 12 feet wide at the based with a center height of just over six feet. Pipes should be painted with a latex paint. Experience has shown that non-painted pipe may cause plastic to degrade where it comes in contact with the pipe.

End walls were constructed the previous season. These are made from 2x4 lumber and have a number of aluminum channels attached to them for fastening plastic. They are quickly put in place and attached to the end loops. In addition, ropes are run from either side of the door to anchors that are sunk deep into the ground. Mobile home anchors are inexpensive and work well for this purpose.

A lightweight metal pipe is then attached to each bow using aluminum cross connectors. A typical source of pipe would be the top rail for a chain link fence. This pipe is very important as it gives the entire tunnel rigidity. Demonstration plots showed that tunnels with the center pipe withstood very strong (60 mph) wind gusts while those without the pipe did not. The rigid pipe also helps shed water after rains.

Ropes are then attached to anchors at each end and attached to the first three bows on either end in crisscross fashion. These ropes help tighten the tunnel and improve end-wall stability.

Plastic is then unrolled and pulled over the house. Because the plastic is meant to be removed during the winter months, a lighter weight (4 millimeter) plastic can be used if desired. However, 6 millimeter plastic has shown to be able to withstand wind to a much greater extent than 4 millimeter in central KY. Once pulled over the hoops, the ends of the plastic are attached to the endwalls using "wiggle wire" put into the pre-fastened channels (shown in the far right photo).

Then nylon rope is fed back and forth over the plastic attaching to the hooks that were welded on the side of the anchors. The rope is sent down the tunnel and attached to every other hook then it is brought back up the tunnel and attached to the remaining hooks. The rope is twisted at each hook so that the rope can be easily tightened as needed. By using the rope to hold the plastic cover down, one does not have to permanently affix the plastic to any base. Therefore when warm weather strikes the plastic can be pulled up on each side easily venting the crop inside. In fact, this type of structure was used to grow organic colored bell peppers during the summer in Lexington, KY. It served to keep rain off of the peppers, reducing fruit rot and the spread of bacterial spot of pepper.

Total assembly time for a 160 foot long tunnel from start to finish can be done with 2-3 people in about 3-6 hours, depending on experience level. The end walls would take an individual about 2 hours each to build. While these tunnels only give about 2-3 oF of frost protection alone-more if an additional layer of plastic or remay is placed in the tunnel, they effectively increase the number

of hours above 50 oF when used in spring. Thus they promote rapid growth and early fruit when used for tomatoes. Above is a picture taken on June 20, 2008, in the mountain region of East KY. The plastic had been removed, but one can easily see the difference in growth and fruit set on the tomatoes 'Mt. Crest' planted in the tunnel and those outside the tunnel. Both were planted on the same day in late April 2008. While not for everyone, these inexpensive tunnels can give growers a jump on the season without a large investment of capital.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

Low-Cost cu efect de seră construcții

Pas cu pas direcţii pe cum de a construi propriul low-cost, înalt tunel, cu efect de seră pentru toamna și iarna sezon extensia.

De Tim Coolong, Universitatea din Kentucky Fotografie de credite: Tim CoolongVizitaţi: www.extension.orgVezi și: Ridicat tunel Video de prezentare

Tim Coolong este un profesor asistent la Universitatea din Kentucky. Dr. Coolong funcţionează în primul rând cu mici ferme mixte de legume în jurul Kentucky. Cercetările sale are axat pe gestionarea durabilă pentru productia vegetala mixte, inclusiv gestionarea de irigare, culturi noi şi extensia de sezon.

Serele tunel înaltă (colacul casa) devin din ce în ce mai popular pentru utilizarea de către ferme mici, care adesea de piaţă direct către consumatori. Deşi acestea s-au dovedit a fi avantajoasă agricultorilor care doresc să valorifica pe preţuri ridicate obținute fie mai devreme sau mai târziu în sezonul creştere, structurile tunel ridicat permanente reprezintă o investiție capitalului semnificative. Costul pentru un tunel de dimensiune standard, inclusiv plastic (două straturi) și toate materialele necesare pentru construcția poate varia de la $1.50-2.50 dolari pe picior patrat fără taxe muncii si transport. Aceasta reprezintă o investiţie iniţială de mai multe mii de dolari, care este pur şi simplu prea mult pentru unele ferme mici. Deși majoritatea cultivatorilor sunt în măsură să plătească pentru lor tuneluri în termen de câteva sezoane, în creştere alţii nu poate justifica investiției. Din acest motiv,

personalul de extindere şi de cercetare la Universitatea din Kentucky au fost de lucru pe în curs de dezvoltare un tunel de mare low-cost, acoperit cu un strat unic de plastic care pot fi asamblate sau mutat într-o după-amiază.

Acest tunel low-cost de înaltă oferă numai aproximativ 3 of protecții îngheț, comparativ cu 7 of pentru un tunel poli dublu. Acest tunel design sa dovedit a rezista la 60 mph vânt cu puţine daune în KY. centrală și de vest Acest tunel nu rezistă mult mai mult decât un eveniment foarte uşoare de zăpadă (< 1 inch), cu toate acestea, nu este menit să fie utilizate prin-iarna în părţi ale ţării, care primesc ninsoare semnificative. Cel mai bun timp pentru a utiliza acest tunel este pentru câteva luni în primăvara timpurie şi mid-fall care primiţi zilnic de temperaturile scăzute și ingheturi uşoară. Demonstraţii în centrală şi de Est KY au arătat că cultivatorii puteţi ajunge la piaţa până la de trei-patru săptămâni mai devreme, cu tomate cultivate în acestui tunel decât în câmpul. Adăugat veniturilor din aceste devreme tomate deplasează mai mult costurile iniţiale.

Beneficii suplimentare la acest tip de design includ capacitatea de a face tunel atâta timp cât este necesar. Deoarece mare parte a muncii este în construirea endwalls, nu există de mult diferență la nivelul costurilor muncii pentru construcţia un picior 300 de tunel lung, comparativ cu un tunel lung de picior 100. În mod evident, costurile materiale sunt mai multe, dar permite flexibilitate pentru cultivatorul în funcţie de condiţiile de piaţă. Un alt pozitiv pentru cultivatorilor organici este în special capacitatea de a uşor dezasambla tunel şi mutaţi-l dintr-o locaţie la alta. Unul dintre centrale tenets de agricultura ecologica este ideea de rotație a culturilor. Din păcate, cu unele dintre tunelul ridicat mai multe permanent structurile corespunzătoare de rotație este dificil. Adesea cultivatorii găsi aceeași cultură în aceeaşi locaţie în creştere de mai mulţi ani. Eşec pentru a roti culturile anuale sunt conforme cu cerințele ecologice și, în multe cazuri rezultate nivelelor ridicate de bolile solului. Cultivatorilor organici în special au trebuit să se adapteze pentru a găsi moduri creative pentru a se ocupa de aceste boli, inclusiv altoire portaltoaie rezistente, biofumigants și sol Solarizare. Fiind capabil de a face o mutare rapidă un tunel permite cultivatorii să rotiţi cu uşurinţă și evită multe din aceste probleme. Următoarele sunt pas cu pas instrucţiunile despre cum să adune acest tip de tunel. Acest design este fiind constant modificat pentru a găsi cele mai cunoașterea utilizării de bani şi muncii încă oferind o structură utile voinic în acelaşi timp. Mai jos este o schiţă detaliată privind modul de a construi acestui tunel.

Construirea mari tunel cu efect de seră

În acest tunel avem deja stabilite de plastic în câmpul şi transplantat. Prin asamblarea tunel peste paturi format deja putem folosi tractorului tradiţionale bedshapers de plantat și răsădit, salvarea necesitatea echipamente specializate. Aici ancorele sunt realizate din diametrul de un inch piese de țevi din oțel 24 de centimetri în lungime, cu o singură rândul său, de zbor auger sudate la sfârşitul. Kleet este approxiametly sudate de 18 inch pe ancoră.

Aceste ancorele sunt plasate pe piciorul opt centre pe întreaga lungime a tunelului. Genrally sunt distanțate 12 de picioare în afară, care este suficient pentru a acoperi uşor două paturi făcute pe centre de şase picioare.

Ancore sunt augured apoi în pământ, cu un mic hidraulic acționat motor care poate fi cuplat la un tractor. Ancorele sunt conduse în pământ, astfel încât "cârlig", care este sudate partea este doar la nivelul solului.

Apoi 1.5 inch program 40 pvc conducte se așează peste ancore. De obicei țeava pot fi achiziţionate în picior 20 lungimi. O țeavă de 20 picior va forma un tunel de 12 metri lăţime la baza cu o înălțime de centrul de peste şase picioare. Conducte trebuie să fi vopsite cu o vopsea de latex. Experiența a arătat că țeava non-pictat poate provoca a se degrada în cazul în care vine în contact cu conducta de plastic.

Sfârşitul zidurile au fost construite sezonul precedent. Acestea sunt făcute la 2 x 4 cherestea şi au un număr de canale de aluminiu ataºat pentru prindere din material plastic. Rapid, ele sunt de a pune în aplicare şi ataşat la sfârşitul buclele. În plus, cabluri se execută din oricare parte a ușii la ancorele care sunt scufundate adânc în sol. Mobil acasă ancorele sunt ieftine şi de a lucra bine în acest scop.

O ţeavă de metal usoare apoi se atașează la fiecare arc folosind aluminiu cruce conectori. O sursă tipic de conducte ar fi șină sus pentru un gard de link-ul de lanţ. Această conductă este foarte important ca oferă rigiditate întreaga tunel. Parcelele de demonstraţie a arătat că tuneluri cu țeavă centrul a rezistat rafale de vânt foarte puternic (60 mph) în timp ce cei fără conducta nu. Conducta rigide ajută, de asemenea, şi-a vărsat apă după ploile.

Cabluri sunt apoi ataşat la ancorele la fiecare capăt şi ataşat la arcuri primele trei pe oricare scop la moda crisscross. Aceste cabluri ajuta strânge tunel și să îmbunătățească stabilitatea sfârşitul-perete.

Apoi, din material plastic este unrolled şi tras peste casa. Deoarece plastic este menit să fie eliminate în lunile de iarnă, o brichetă de greutate (4 milimetri) din material plastic poate fi utilizat dacă doriţi. Cu toate acestea, 6 milimetri de plastic a demonstrat ar fi să poată rezista la vânt într-o mult mai mare măsură decât 4 milimetri în KY. centrală Odată ce s-a tras peste cercuri, capetele de plastic sunt anexate la endwalls folosind "wiggle sârmă" pune în canale pre-fastened (prezentată în extremitatea din dreapta foto).

Apoi nailon coarda este alimentat înainte şi înapoi peste ataşarea la cârlige care au fost sudate pe partea laterală a ancore de plastic. Frânghie este trimis în jos tunel şi ataşat la fiecare alte cârlig, apoi este adus înapoi până tunel şi ataşat la cârlige rămase. Cablului este sucit la fiecărui cârlig, astfel încât frânghie pot fi strânse cu uşurinţă, în funcţie de necesităţi. Prin utilizarea de frânghie apăsării pe coperta din plastic, una nu trebuie să aplice permanent de plastic la orice bază. Prin urmare, când vremea calda greve plastic poate fi tras pe fiecare parte cu uşurinţă în atmosferă culturilor în interiorul. De fapt, acest tip de structură a fost folosit să crească organice ardei colorate în timpul verii în Lexington, KY. A

servit pentru a păstra ploaie off de ardei, reducerea veștejirii bacteriene fructe şi răspândirea de bacterii la faţa locului de ardei.

Timpul total de asamblare pentru un tunel lung de 160 picior la început la sfârşit se poate face cu 2-3 persoane în aproximativ 3-6 ore, în funcţie de nivelul de experienţă. Zidurile sfârşitul ar lua un individ aproximativ 2 ore fiecare pentru a construi. În timp ce aceste tuneluri da numai despre 2-3 of îngheț protecția singur-mai în cazul în care un strat suplimentar de plastic sau

remay este plasat în tunelul, care măresc efectiv de numărul de ore anterior 50 of atunci când este utilizat în primăvara anului. Astfel le promovează creşterea rapidă și începutul fructe atunci când este utilizat pentru tomate. Mai sus este o imagine în luate pe 20 iunie 2008, de în regiunea de munte din est KY. Plastic au fost eliminate, dar se poate vedea cu uşurinţă diferența de creştere şi fructe pe tomate "Mt. Crest" plantate în tunel şi cele din afara tunelului. Ambele au fost plantate în aceeași zi la sfârșitul lunii aprilie 2008. În timp ce nu pentru toată lumea, aceste tuneluri ieftine pot da cultivatorii un salt pe sezon fără un mare de investiţii de capital.

Acesta este un articol de eOrganic şi a fost revizuit pentru conformitatea cu reglementările Programul Naţional de biologică de membri din Comunitatea eOrganic. Întotdeauna verificaţi cu Agenţia dumneavoastră certificare ecologica înainte de a adopta noi practici sau utilizarea noilor materiale. Pentru mai multe informaţii, consultaţi eOrganic lui articole pe certificare ecologica.

Home-made Polytunnel

A small polytunnel can be quite useful throughout the year for many different purposes. It can extend your growing season and allow you to grow more tender crops than in the open ground. In the early spring, it can be used for

germinating and growing bedding and vegetable plants earlier than would otherwise be possible. In the summer it can be used for growing more tender vegetables such as Tomatoes and Peppers or for root cuttings. It can be used in the autumn to start winter vegetable plants. During the winter, it can protect patio plants and other hardy but containerised woody plants.

Commercial polytunnels can be expensive to buy but a home-made polytunnel can be built easily and inexpensively in several hours using simple hand tools and materials available at most building supply or D.I.Y stores.

These instructions and plans for building your own polytunnel can easily be adapted to suit your owns needs as to size. Measuring 12 feet by 14 feet (168 square feet), it is small enough to be unobtrusive but large enough to meets the needs of the serious grower. The completed structure is shown above.

Selecting a Site

Choose a level, well-drained plot for the polytunnel. If it will be used primarily for plant propagation in the summer, place it in partial shade to minimise heat build-up. If a partially shaded site is not available, you can use shade cloth or a white plastic cover to control the amount of sunlight reaching the interior.

If the polytunnel will be used for starting transplants or growing plants to maturity, it will need maximum exposure to the sun. It should also be located where air drainage is good; avoid low areas surrounded by woods or buildings.

Constructing the Polytunnel

Cutting List

Qty Description

16 3/4" PVC pipe, 10 feet long6 3/4" PVC crosses (Please Note: Since I wrote this article in 1998, I have since found that the PVC cross sections are no longer in production. I therefore suggest 20mm electrical cross inspection boxes.) 2 3/4" PVC tees 32 3/4" Plastic or copper clips 2 2"x6"x14' treated pine boards 2 2"x6"x12' treated pine boards 4 2"x4"x7' treated pine boards 4 2"x6"x6' treated pine boards 4 4"x4"x2' treated pine boards 2 2"x4"x3' treated pine boards 2 1"x4"x12' treated pine boards (to be cut up for door parts) 1 Set of door hinges

1 Sheet of plastic, 24'x20' 1 Can of PVC cleaner 1 Can of PVC cement 1 1/2"x10' galvanised electrical metallic tubingPlus Miscellaneous nails, screws, and staples

Assembly Plan

The polytunnel consists of a wooden frame to which are attached hoops of PVC water pipe. The hoops support the clear plastic film covering.

All timber for construction should be treated with preservative. This can either be purchased as ready treated (ask for Tanalised Timber) or treated separately. Avoid wood preserved with creosote as this can be detrimental to the plants grown in the polytunnel. Tanalised timber is pressure

treated with the preservative and therefore will last much longer than untreated or lightly treated wood. Except for the covering, the structure should last 10 to 12 years.

Unless the site is very flat, you will need to level the ground prior to

construction. The purpose of the 4-inch-by-4-inch post at each corner is to anchor the polytunnel and prevent it from moving in high winds. It also provides a convenient way of jointing the boards together.

The PVC pipe hoops are attached to the inside of the foundation boards with clips. These are sold to secure plastic and copper water pipe in place and are usually copper or plastic. The plastic ones are probably better as they will not rot but the copper ones are probably stronger but will have to be replaced every few years. It is best to attach the clamps loosely to the side boards with wood screws before you secure the side boards to the end boards and corner blocks. They may be tightened after the PVC pipe has been slipped into place.

The 12-foot width of the polytunnel was chosen so that each half of the rib section of pipe is 10 feet long. PVC pipe may be easily cut with a hand saw, although a neater cut can be made with a pipe-cutting tool specially designed for that purpose. The joints at the cross sections are cemented using a special adhesive that is sold specifically for this purpose and can be bought from the supplier of the pipe. Care must be taken during assembly because the cement used to fasten PVC is fast-acting and permanent and care should be taken when using the adhesive. Always follow the directions on the tin.

It is best to lay all parts out on a flat surface for assembly. For the ribs to be 2 feet apart, the midrib pipe must be cut into pieces about 22 1/2 inches long. After all joints have been cemented and allowed to harden for a few minutes, position the entire assembly over the foundation boards, bend the ribs, and secure them in place with the clips.

Assembly is best done by two or more people to prevent over stressing the cemented joints. Ten feet of galvanised metal tube positioned inside the midrib will give added strength to the structure.

After all the PVC ribs have been secured, the end frames and door may be constructed. Although there is a door on only one end, both frames are essentially the same. The two diagonals on each end give strength to the structure and make it easy to secure the cover. The top of the end frame may be fastened to the end ribs with either a wood screw or a small metal strip bent into a U shape. If wood screws are used, the PVC pipe must be pre-drilled to prevent splitting. (2005 Note: It has been pointed out to me by a couple of people making this polytunnel that they have required additional diagonal supports on the ends of the polytunnel. This is to stop the end pieces of tubing from distorting when the polythene is tightened. They have fitted the additional supports from the base of the door to the center of the end hoops on each side. Personally, I did not find this a problem so perhaps they were over tightening the polythene!)

Select the type of cover material according the intended use of the polytunnel. Clear plastic polytunnel film is generally best if the tunnel will be used for growing plants. If it will be used exclusively for propagating or overwintering plants, consider using milky or white copolymer film. White copolymer film reduces the amount of heat and light within the house and therefore limits the fluctuations in these factors, keeping conditions more nearly constant during propagation or over the winter. However, shading clear plastic with a 30 to 50 percent polypropylene shade netting or polytunnel whitewash available from horticultural supply companies will produce nearly the same effect.

The cover may be attached with small tacks, but staples are much faster and are more secure. Allow the cover to extend several inches past the bottom of the foundation boards and cover the extra material with packed soil to prevent the entrance of rainwater.

Use of the Polytunnel

It is essential that the house be as tight as possible so that it retain both heat and humidity. Problems with overheating can usually be solved by simply opening the door. If the polytunnel is placed in a site where electricity is made available a fan can help in ventilation. Supplemental heat can be provided if needed during very cold weather or at night by one or more heat lamps or a small electric heater. Any electrical devices used in the damp environment of a polytunnel should be connected only to a circuit equipped with an approved circuit breaker. Other source of heat can be used, but even very small gas or oil heaters will usually overheat a polytunnel this small and may not burn well if not properly ventilated.

The polytunnel will satisfactorily support up to 4 inches of dry snow. If the snow is deeper or wet, one or more temporary supports should be provided along the midrib to prevent the structure from collapsing. If a larger polytunnel is required, the length may be increased. Do not increase the width of the house without increasing the size of the ribs. Doing so will seriously reduce the ability of the house to withstand snow and wind loads.

Home-a făcut Polytunnel

Un mic polytunnel poate fi destul de util pe parcursul întregului an pentru multe scopuri diferite. Poate extinde vă sezonului de creştere şi vă permite să crească mai multe culturi licitaţie decât în sol deschise. La începutul primăverii, acesta poate fi utilizat pentru germinating şi cultivarea plantelor aşternut şi legume mai devreme decât ar fi altfel posibil. În vara, poate să fi utilizat pentru cultivarea legumelor de ofertă mai multe, cum ar fi tomatele și ardei sau pentru butași de rădăcină. Poate fi utilizat în toamna pentru a porni plante de legume iarna. În timpul iernii, se poate proteja plante a terasă şi alte hardy dar răsădite lemnoase plante.

Polytunnels comerciale poate fi scump pentru a cumpara, dar un home-a făcut polytunnel poate fi construit, uşor şi ieftin, în câteva ore utilizarea simplu parte instrumente şi materiale disponibile cel mult construirea de aprovizionare sau D.I.Y magazine.

Aceste instrucţiuni şi planurile pentru construirea propria polytunnel poate fi uşor adaptat pentru a se potrivi vă detine nevoile în ceea ce privește mărimea. Măsurarea 12 de picioare de 14 metri (168 de metri pătraţi), este suficient de mic pentru a fi discret, dar suficient de mare pentru răspund nevoilor cultivatorului grave. Structura completat este arătat mai sus.

Selectând un Site

Alegeţi un nivel, bine drenate complot pentru polytunnel. În cazul în care vor fi utilizate în principal de înmulțire de plante în vara, plasaţi parţială umbra pentru a minimiza acumulării de căldură. În cazul în care un site parţial umbrită nu este disponibilă, puteţi utiliza umbra cârpă sau un capac din plastic alb pentru a controla cantitatea de lumină solară care ajunge la interior.

Dacă polytunnel va fi utilizat pentru pornirea transplanturi sau cultivarea plantelor la maturitate, va trebui maxim de expunere la soare. Ar trebui să fie amplasate în cazul în care aerul drenaj este bun; Evitaţi scăzut zonele înconjurată de pădure sau de clădiri.

Construcţia Polytunnel

Listă de tăiere

Cant. descriere

16 3/4 "PVC conducte, 10 de picioare lungi6 3/4 "PVC cruci (Vă rugăm să reţineţi: din moment ce am scris acest articol în 1998, am deoarece găsit care PVC secţiuni transversale nu mai sunt în producție. Prin urmare, sugerez 20 mm electrice cruce casetele de control.) 2 3/4 "PVC tees 32 3/4 "De plastic sau cupru clipuri 2 2 "x 6" x 14' tratate PIN camerelor 2 2 "x 6" x 12' tratate PIN camerelor 4 2 "x 4" × 7 "tratate PIN camerelor 4 2 "x 6" x 6' tratate PIN camerelor 4 4 "x 4" x 2' tratate PIN camerelor 2 2 "x 4" x 3' tratate PIN camerelor 2 1 "x 4" x 12' tratate PIN panouri (pentru a fi tăiate pentru uşa părți) 1 Set de balamale USA Foaia 1 din material plastic, 24'x 20' 1 Poate de PVC curat 1 Poate de din PVC ciment 1 1/2 "x 10' zincat tub metalic electriceÎn plus, diverse cuie, șuruburi, și staples

Plan de asamblare

Polytunnel constă într-un cadru din lemn, la care sunt atașate cercuri de PVC conducte de apă. Cercuri acceptă acoperire folie de plastic clar.

Toate din lemn pentru construcții trebuie tratate cu conservant. Acest lucru fie poate fi cumpărat ca gata tratate (a intreba pentru lemn de Tanalised) sau tratate separat. Evitaţi lemn conservate cu creozot ca acest lucru poate fi dăunătoare plantelor cultivate în polytunnel. Tanalised din lemn

este tratează sub presiune cu conservant și, prin urmare, va dura mult mai mult decât lemn netratat sau uşor tratate. Cu excepția pentru acoperind, structura ar trebui ultimii 10 până la 12 ani.

Dacă site-ul este foarte plat, va trebui să nivelul solului înainte de construcție. Scopul post 4-inch-de-4-inch în fiecare colţ este de a polytunnel de ancorare și de a împiedica mutarea în vânturile. De asemenea, furnizează un mod

convenabil de a îmbinărilor plăcilor împreună.

PVC conducte cercuri sunt atașate în interiorul camerelor de Fundaţia cu clipuri. Acestea sunt vândute la sigur din material plastic și cupru țeavă apă în loc şi sunt, de obicei, din cupru sau din plastic. Cele din plastic sunt, probabil, mai bine ca vor putrezi nu, dar cele de cupru sunt, probabil, mai puternice, dar va avea să fie înlocuite cu fiecare câţiva ani. Este cel mai bun pentru a ataşa clemele vag la panourile laterale cu șuruburi înainte de a vă securiza panourile laterale scop comisii şi colţ blocuri. Ele se pot strânși după PVC conducte a fost alunecat în locul.

Lățimea 12-picior de polytunnel a fost ales astfel încât fiecare jumătate din secţiunea coaste țevii de 10 de picioare lungi. PVC conducte pot fi uşor tăiate cu o mână de văzut, deşi o tăietură neater poate fi făcută cu o țeavă-tăiere instrument special concepute în acest scop. Articulaţiilor la secţiuni transversale sunt cimentat folosind un adeziv speciale, care este vândut în mod specific pentru acest scop şi pot fi cumpărate de la furnizorul de conducte. Îngrijire trebuie luate pe parcursul asamblării deoarece ciment utilizate pentru a se agăţa de PVC este rapidă și permanentă și se acordă atenție când utilizaţi adezivă. Întotdeauna urmaţi instrucţiunile privind staniul.

Este cel mai bun pentru a pune toate părțile pe o suprafață plană de asamblare. Pentru coaste să fie 2 metri în afară, țeava de midrib trebuie să fie tăiate în bucăți aproximativ 22 1/2 centimetri lungime. După toate rosturile au fost cimentat şi permisiunea de a întări pentru câteva minute, poziţionaţi întregul ansamblu peste camerelor Fundaţiei, îndoiţi coaste şi sigur-le în loc cu miniaturile.

Adunarea se face cel mai bun prin două sau mai multe persoane pentru a preveni peste subliniind articulaţiilor pavată. Zece metri din oţel zincat tubului metalic poziţionat în interiorul midrib va da puterea adăugat la structura.

După ce au fost depuse toate coastele din PVC, sfârşitul cadre şi USA pot construite. Deşi există o ușă de doar un singur capăt, ambele cadre sunt în esenţă acelaşi. Diagonale două pe fiecare capăt da puterea la structura şi asiguraţi-o usor pentru a asigura acoperirea. Partea superioară a cadrului sfârşitul poate se atașează coaste sfârşitul cu un lemn şurub sau cu o mică fâşie metalice aplecat în formă de U. Dacă sunt utilizate șuruburi, PVC conducte trebuie să fie preforat pentru a evita scindarea. (2005 Nota: S-a subliniat la mine de un cuplu de oameni de luare această polytunnel că acestea au necesare diagonală suplimentare acceptă pe capete polytunnel. Aceasta este pentru a opri piese sfârşitul de tub la deformarea când se strânge folie de polietilenă. Acestea au echipate sprijină suplimentare de la baza USA la centrul de cercuri sfârşitul pe fiecare latură. Personal, nu am găsit acest lucru o problemă atât de probabil au fost peste înăsprirea polietilenă!)

Selectaţi tipul de material de acoperire în funcţie de utilizarea preconizată a polytunnel. Polytunnel clar din plastic filmul este în general mai bune dacă tunelul va fi utilizat pentru cultivarea plantelor. În cazul în care vor fi utilizate exclusiv pentru materialului săditor sau a overwintering plantelor, luaţi în considerare utilizarea filmul datorită lăptos sau albe. Datorită alb filmul reduce cantitatea de căldură și lumină în casă și, prin urmare, limitele fluctuațiile de acești factori, păstrarea condițiilor mai aproape constante în timpul înmulțirii sau peste iarna. Cu toate acestea, umbrire clar de plastic cu un 30-50 la sută din polipropilenă umbra plasă sau polytunnel văruit disponibile de la companii de aprovizionare horticole va produce aproape acelaşi efect.

Acoperirea poate fi fixat cu crampoane mici, dar sunt mult mai rapid și sunt mai sigure. Permite acoperirea a extinde mai multe inch trecut de partea de jos a camerelor Fundaţiei şi acoperi material suplimentar cu sol ambalate pentru a preveni intrarea apei de ploaie.

Utilizarea Polytunnel

Este esențial ca casa fie bine posibil, astfel încât el să păstreze căldura și umiditatea. Probleme cu supraîncălzire, de obicei, poate fi rezolvată prin pur şi simplu deschide uşa. Dacă polytunnel este plasat într-un site care energia electrică este pus dispoziția

un fan poate ajuta în ventilație. Căldură suplimentare pot fi furnizate, dacă este necesar în timpul vremea foarte rece sau noaptea de una sau mai multe lămpi de căldură sau un incalzitor electrice mici. Orice dispozitive electrice utilizate în mediu umed de o polytunnel ar trebui să conectat numai la un circuit echipat cu un disjunctor aprobate. Alte sursă de căldură poate fi folosit, dar chiar foarte mici de gaz sau încălzitoare de ulei, de obicei, va supraîncălzi un polytunnel acest mic şi nu pot arde ventilate bine dacă nu sunt corect.

Polytunnel va sprijini satisfăcător până la 4 centimetri de zăpadă uscat. În cazul în care zăpada este mai profundă sau umed, una sau mai multe suporturi temporară trebuie să aibă de-a lungul midrib pentru a împiedica restrângerea structura. Dacă este necesară o mai mare polytunnel, lungimea poate fi mărită. Nu creşte lăţimea de casa fără să creşteţi dimensiunea coaste. Acest lucru serios va reduce capacitatea casa de a rezista încărcături de zăpadă şi de vânt.