Greenhouse Operations Management: Greenhouse Structures Notes · 2018-07-17 · Greenhouse...

Greenhouse Operations Management GOM1 Greenhouse Structures

Greenhouse Operations Management: Greenhouse Structures Notes

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Structures, Frame Styles, and Coverings:




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Greenhouse Site Selection: Greenhouse Interiors - Layout: Greenhouse Interiors – Benching:




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Greenhouse Interiors – Flooring: Additional Considerations: Environmental Concerns:


Greenhouse Operations Management: Greenhouse Structures GOM1.1

Greenhouse Structures, Frames and Coverings

Greenhouse Structures Freestanding

It’s easy to manage the upkeep of freestanding greenhouse structures. Snow removal,

temperature regulation, and ventilation are simple because the structure is not connected to any

other structure. They also boast the advantage of providing uniform light. However, freestanding

structures are more expensive to build, and require more energy and space.

Connected

Connected greenhouse structures are built together and share a single roof. They are easier to

construct, and require fewer building materials. Walls inside the connected structures delineate

zones for different kinds of plants. Less energy is expended when heating and cooling the

connected structures because of the advantage of the shared walls. However, it is harder to adjust

temperatures or apply insecticides in specific zones within the connected structure. It is also

difficult to remove snow from the roof and gutters. Connected structures also have more

shadows and less light.

Lean To

The lean-to is a modified connected greenhouse structure. It is built facing east or south, and

shares one wall with an existing structure. It is a small structure, generally only 7 to 12 feet wide,

with not much room inside. Utilities like heat, water, and electricity come from the connected

building. The lean-to does not have good roof support. Growers often use a lean-to for starting

seeds.

Greenhouse Frames Gothic Arch

The Gothic Arch frame is a freestanding structure. It is built in a rounded style, with a subtle

peak at the top of the roof. This allows for ample room inside for the growing of potted plants

and spring annuals.

Quonset

Quonset frames are freestanding structures, developed during World War II. They are entirely

rounded, and simple to build. Their rounded shape takes storage space away from the walls and

cuts into the space overhead.

A-Frame

The A-Frame is a freestanding structure. Each side of the roof runs straight from the ground to

the tip of the roof. It is a straightforward design that uses less material than a standard even span.

A-frames have ample space along the walls, and boast good air circulation.



Cold Frames

Outdoor growing structure with transparent covering; heated only by the sun, top opened during

the day, closed at night; used to harden and protect plants from frost, winter storage of bulbs.

Hotbeds

Outdoor growing structure with transparent covering; used by steam, hot water, or electricity;

used to start seedlings or cuttings.

Lath Houses

Outdoor growing structures covered with lath or shade fabric supported by vertical poles;

reduces light intensity, used in summer in temperate climates or year-round in warm climates.

Even Span

The even span frame has a symmetrically framed roof. It has good air circulation, adequate

space, and encourages even temperature maintenance within the greenhouse.

Uneven Span

The uneven span frame has a roof with asymmetrical gables. It is often built on shallow hillsides

facing south, in order to take advantage of winter light.

Greenhouse Coverings Glass

Glass is strong and allows for ample light to enter the greenhouse. It’s long-lasting and easy to

maintain. However, it’s breakable and requires a sturdy frame for support, which can be

expensive.

Polyethylene Film

This covering is flexible, lightweight, and easy to install. A light frame is adequate to support

polyethylene film. The film is also effective in transmitting adequate light. However, it requires

frequent maintenance and replacement, and is vulnerable to damage.

Polycarbonate

Polycarbonate forms rigid plastic panels with which to cover a greenhouse. It is light and

durable, but not as strong as glass. It transmits light well, although not infallibly, and does

require regular replacements.



Structures, Frames, and Coverings

Name of Structure Pros Cons

Freestanding

Gutter Connected

Lean To



Name of Frame Pros Cons

Gothic Arch

Quonset

A-Frame

Even Span

Uneven Span




Cold Frames

Hotbeds

Lath Houses

Name of Covering Pros Cons

Glass

Polyethylene Film

Polycarbonate


Greenhouse Operations Management: Greenhouse Structures GOM1.2 KEY

Structures, Frames, and Coverings

Name of Structure Pros Cons

Freestanding Easy to manage in

regard to snow

removal, temperature

regulation, and

ventilation. Provide

uniform light.

More expensive to

build, and require

more energy and

space.

Gutter Connected Occupy less land;

need fewer materials

for construction. More

interior space due to

no sidewalls. Less

energy required to

heat and cool due to

reduction in wall

surface area.

During winter

months, snow collects

in the gutters or ridges

and creates load-

bearing problems on

the roof. Collapsing

may occur during

heavy snows and/or

accumulation.

Lean To Least expensive of all

growing structures.

Confined to a space of

7 to 12 feet and less

roof support than

other structures.




Gothic Arch Provides ample

headroom.

Lower sidewall height

may reduce storage

space and headroom.

Quonset Extremely simple to

construct and

efficiently designed.

Circular frame

decreases sidewall

height, which limits

headroom and storage

space.

A-Frame Provides more space

along the sidewalls,

which promotes good

air circulation.

Space not as

functional and air

flow may be

problematic in the

corners of the

structure.

Even Span Has more usable

space than other

types, promotes good

air circulation,

maintains even

temperatures

Most structures have

overlapping panes and

can be more prone to

leaking than other

structure styles

Uneven Span Captures low light

during winter months.

More difficult to build

since the

measurements are odd




Cold Frames Good for hardening

plants, protecting

plants from frost, and

storing bulbs during

the winter

Must receive

appropriate heat from

sun only

Hotbeds Easier to control heat

levels (heated by

steam, hot water, or

electricity); good for

starting seedlings or

cuttings

More expensive,

requires more

management than a

cold frame

Lath Houses Good for tropical

plants or plants which

need shade

Must receive

appropriate heat from

sun only; best for use

in summer or warm

climates

Name of Covering Pros Cons

Glass Good light

transmission and

easily available

Breakable, high heat

loss, and the most

expensive

Polyethylene Film Inexpensive and easy

to install. Can be

applied in single or

double layers.

Short life span, 5

years or less before

replacement

Polycarbonate Lightweight and

durable.

It is more expensive

than polyethylene

film.



Greenhouse Building Site

Rate three potential greenhouse sites based on the criteria in the left column of the table below.

Enter ratings as numerical values according to the key below.

1 = Does not meet criteria well

2 = Condition of the site is passable

3 = Site meets the criteria perfectly

Once the table is complete, add the values in each column. Whichever site scores the highest

should be chosen as the best building site.

Criteria Site #1 Site #2 Site #3

No obstructions to the

East or South

0% - 5% Ground Slope

Access to Water

Is there enough space

for the 100’ ridge to run

North to South?

Totals:



Layout, Bench, and Flooring

Sketch Name About

Longitudinal

Peninsula

Island

Stationary



Sketch Name About

Rolling Top

No Benches

Pyramid Frame

Sectional/Transportable



Sketch Name About

Benches

Concrete flooring

Gravel flooring



Layout, Bench, and Flooring

Sketch Name About

Longitudinal

Water/heat lines do not affect

walkways. Inefficient; workers

must walk all the way around to

get to the other side

Peninsula

Good for container-grown

plants, starter plants, flowering

annuals; easy access to plants;

more area for growing plants

Island

Efficient center aisle allows

workers to access both benches.

Useful for bedding and

container-grown plants.

Stationary

Can only be used in their

original position, cannot be

moved.



Sketch Name About

Rolling Top

Maximize use of floor space,

use less aisle space. Intended

for wholesale use only.

No Benches

Low cost, some flexibility in

layout. Extra labor placing,

spacing and lifting crop; cold

roots impact quality unless you

put hot water heat in floor.

Pyramid Frame

Better visual display, faster turn

at retail sales. Fewer plants can

be displayed than on benches,

extra costs with materials.

Sectional/Transportable Dramatic improvement in labor

efficiency, can automate using

robots for a number of tasks,

best use of floor space. Difficult

to pick small orders. More

expensive to install, requires

greenhouse to be configured to

take advantage of product flow.



Sketch Name About

Benches

Gets crop up where one can

more easily work, mesh tops

allow improved air flow and

improves plant quality, allows

heat to go under the bench. Too

many aisles reduce crop

efficiency.

Concrete flooring

Slope toward drains

Gravel flooring

A weed mat covered with

gravel. Porous enough to allow

water to drain.



Greenhouse Environmental Controls

Heating

What do greenhouse owners/designers need to know or understand about heating?

Explanation Pros Cons

Wood Burning

Furnace

Infrared System

Solar

Gas Powered Heaters



Ventilation and Cooling

What do greenhouse owners/designers need to know or understand about ventilation and

cooling?


Exhaust Fan and

Louver System

Horizontal Air Flow

Fans

Fan & Pad Coolers

Retractable Roof and

Vent Kits

Retractable Side-

Walls



Irrigation

What do greenhouse owners/designers need to know or understand about irrigation?


Overhead

Drip

Misting

Ebb and Flood

Benches and Floors

Circulating PVC

System

Hand Watering



Greenhouse Environmental Controls

Heating

What do greenhouse owners/designers need to know or understand about heating?

Heat should be efficient, safe, and reliable. Heat is lost through conduction, air infiltration,

and radiation—all lost heat must be replaced.


Wood Burning

Furnace

Water is heated in a

chamber at the back

of large furnaces,

then pumped through

pipe through sand

floors and/or behind

radiator blowers

Works well for

businesses that own

forest land nearby;

sustainable resource

and lower utility bills

Depend on

circulating hot water,

which makes them

nearly impossible to

winterize, and labor

to keep the fires

going 24 hours a day

all winter is costly

Infrared System

Gas-fired burners

heat air distributed

through overhead

pipe system; heat

spreads through

greenhouse as

electromagnetic

waves

Works well for low

growing crops like

bedding plants

Not suitable for tall

crops like cut

flowers; in very cold

weather crops on

edges can suffer cold

damage.

Solar

Collects solar energy

during the day and

releases it at night

Efficient,

environmentally

friendly

Expensive

Gas Powered Heaters

Propane and natural

gas fuel heating units

placed throughout

greenhouse

Widely used;

sometimes readily

available;

comparatively low

installation costs

Expensive; can be

hard to get in isolated

locations; damaged

units can release high

levels of carbon

monoxide



Ventilation and Cooling

What do greenhouse owners/designers need to know or understand about ventilation and

cooling?


Exhaust Fan and

Louver System

Electrically powered

fans pull air across and

out of the house.

Louvers are vents in the

end wall that allow air

to be pulled across by

exhaust fans.

Different sizes

available. Can be

opened and closed with

an electrically powered

shutter-motor kit, or be

designed to passively

open when the exhaust

fans power on.

High startup cost

Horizontal Air Flow

Fans

Circulate warm or cool

air in circular pattern.

Number of fans needed

depends on their power.

Growers test new

systems with colored

smoke that they can see

pass through the

system.

Efficient, reduce disease

and pest problems by

improving air

circulation

Should not be run with

exhaust fans; conflicting

air streams interfere

with each other

Fan & Pad Coolers

Pad of formed paper

spans length of

greenhouse; kept

perpetually wet by

water circulation

system. Vacuum created

by exhaust fans pulls air

through cooling pads.

Could be essential cost

if grower wishes to

grow crop through hot

Missouri summer

Only economical in

smaller greenhouses

Retractable Roof and

Vent Kits

Venting windows along

ceiling, or retractable

roof that can be

electrically opened

during hot weather

Retractable roofs let

growers harden off

plants without moving

them (can save many

labor hours every year)

High startup cost

Retractable Side-

Walls

Side walls are manually

or electronically pulled

up to allow natural

ventilation to passively

pull air through house.

Absolutely the most

cost effective and

energy conserving

method

May not adequately

reduce temperatures for

optimal growth in hot

temperatures



Irrigation

What do greenhouse owners/designers need to know or understand about irrigation?

• Run automatically or manually from a control box

• Often injects fertilizer, water softeners, or pest/disease controls into the water

• Must be winterized if at risk of freezing

• Irrigation systems in greenhouses that will be unheated for a period of time in the

winter must be designed for winterization


Overhead

Uses spray emitters to

rain down water on

plants

Can be a cost-effective

way of watering many

plants

Edges tend to be

watered unevenly and

the centers

overwatered; can lead

to disease problems

Drip

Uses drip emitters to

water by the pot

Conserves water,

prevents the possibility

of disease spreading

when droplets splash

Only cost effective for

crops grown in large

pots

Misting

Light mist of water at

frequent intervals

Greatly increases

germination and rooting

rates

Needs special timer

(can be costly); clogs

easily in places with

mineral rich water

Ebb and Flood

Benches and Floors

Bench/floor designed to

be flooded with water;

pots absorb water from

the bottom up; water

drains off and is reused

Conserves water;

prevents the possibility

of disease spreading

when droplets splash

Possibility of root rot;

salts can clog up system

Circulating PVC

System

Special growing tube of

polyvinyl chloride with

holes which has

nutrient treated water

constantly circulating

through it

Very water efficient;

tends to save a lot of

money

High startup

investment; diseases

such as downy mildew

can spread quickly

Hand Watering

A person uses a hose

and nozzle specific to

plant growing stage to

apply water manually

Inexpensive startup

cost; allows for

selective watering—

prevents overwatering

Time-consuming;

increases labor costs;

increased risk of

spreading disease



Humidity

Amount of water in the air

Measured using a

hygometer

Plants transpire water into

the air, so greenhouses tend

to have higher levels

Rapid changes can cause

tissue damage to leaves

Ideal level for most

greenhouse plants is

between 50% and 60%

Too much requires

ventilation or lower

temperatures

Not enough requires

strategic water bucket

placement to evaporate

water into the air

Misting or watering plants

will also add moisture to

the air



Artificial Lighting

Some crops are subject to

photoperiodism

Most common methods are

fluorescent, metal halide,

and high pressure sodium

lights

LED lights can be used in

combination with other

methods to reduce costs

Can come on in intervals to

save energy

Expensive to purchase and

power

Unnecessary expense for

growing many crops

Before purchase, consider

crop needs, potential

income, and cost of

installing, maintaining, and

powering



Carbon Dioxide

Essential gaseous molecule

used by plants as a reactant

to produce energy during

photosynthesis

Growers can reduce

finishing time for crops by

releasing an appropriate

level

In the winter greenhouse,

plants are especially

susceptible to this

deficiency

During colder months,

when the ventilation

systems are not running

very often, natural levels in

the air become depleted



DIF

Difference between day

and night temperatures

Plants undergo stem

elongation when day

temperatures are warmer—

overgrown leggy plants are

unsellable

In winter, it can be difficult

and costly to keep

temperatures in greenhouse

warmer than daytime

temperatures

By reducing greenhouse

temperature for 2 hours near

sunrise, plants are satisfied

that cooler temperature has

been reached for entire day

Very valuable natural

growth inhibitor for plants

Many environmental

control systems have a

setting for this



Environmental Control Systems & Backup Generators

Can be accomplished with

simple thermostats

Add slightly to startup cost

or renovation costs; save

money in the long run on

labor and energy

conservation

Can be monitored remotely,

which reduces risk of crop

failure in case of system

failure

Essential element of good

greenhouse design



Energy Conservation & Environmental Protection

Keeping the structure in

good repair will prevent

heat loss in winter

Shutting systems down

when the greenhouse is not

in use conserves energy

Alternative energy sources

could reduce overhead

costs in the long run

Using heat sinks like black

concrete floors, crushed

gravel, and water reservoirs

will store heat from sun

Temporary interior ceilings

are widely used by growers

to keep warm or cool air

around plants

Reduce, reuse, and recycle

plastic as much as possible

Be mindful of fertilizer

runoff if the greenhouse

uses conventional methods



Greenhouse Structures 3-D Model and Presentation Evaluation

Correctly construct one of the specific greenhouse structure designs with your choosing of

exterior covering and interior layout. Be creative – use items from supplies provided, from home

and/or around the classroom.

1. Form a 3-D greenhouse structure. Dimensions must not be any larger than 12” width, 12”

length and 12” height. You may choose one of the following freestanding and/or

connected design structures:

• Even span

• Uneven span

• Quonset

• Gothic

• A-Frame

• Connected or Lean To

2. Choose one of the following coverings:

• Glass

• Polyethylene film

• Rigid panels/polycarbonate

3. Choose interior layout and types of benches:

• Longitudinal benching

• Island benching

• Peninsular benching

4. Construct structure according to the specifications established.

5. Choose three of the following areas to develop:

• Work spaces

• Storage areas

• Roadways

• Loading and shipping areas

• Parking areas

• Display areas

• Offices

• Breakroom/kitchen areas

• Restrooms

6. Once structure is completed, use your Greenhouse Operations and Management handout

to complete an eight-slide PowerPoint. It must include the following information:

• Title (include name of your structure, your name, class, hour)

• Three pictures throughout your slideshow (can be imported from websites)

• Supply list and budget of project

• Advantages and disadvantages of chosen structure design

• Advantages and disadvantages of chosen outside covering

• Advantages and disadvantages of chosen interior layout design

• Advantages and disadvantages of chosen types of benches

• Explanation of environmental controls

• Explanation of how greenhouse design conserves energy

• Other 3 options chosen for greenhouse, and an explanation for each



Greenhouse Structures 3-D Model and Presentation Evaluation

Points 0 5 10 15 20

Model and

presentation

of Interior

Layout and

Structure

Model and

presentation

not turned in

Model and

presentation

hastily done;

little detail and

no summary

Model is

acceptable, but

there is no

presentation

completed

Model is

acceptable;

presentation

does not

explain logic

behind design

choices

Model is

acceptable;

presentation

explains logic

behind design

choices

Title Slide and

Pictures

No

presentation

turned in

Title; no

pictures

Title; 1 picture Title; 2

pictures

Title; 3

pictures

Supply List

and Budget

No supply list

or budget

completed

Partially

completed

supply list; no

budget

Supply list

and/or budget

lacks essential

items

Supply list and

budget

complete; lack

detail

Very detailed

and complete

supply list and

budget

Advantages

and

Disadvantages

None listed 2 or fewer

items listed

3 items listed 4 items listed All 5 items

listed

Environmental

Controls

No detail Mentioned

incompletely

Mentioned; no

connection

made to

structure and

interior layout

Connection

made to

features of

structure and

interior layout;

lacks detail

Complete and

clear; connects

to features of

structure and

interior layout

Energy

Conservation

No detail Mentioned;

connection to

structure is

unclear

Some

structural

elements

present; few

details; major

considerations

left out

Conscientious

about energy

conservation;

not feasible or

practical

Conscientious

about energy

conservation;

feasible and

well-detailed

Project Total: ________/120 Points



Greenhouse Structures Evaluation

Multiple Choice:

1. What are the basic parts of the greenhouse structure?

a. Frame and layout

b. Covering and ventilation

c. Frame and covering

d. Flooring and covering

2. What are three interior parts of a greenhouse?

a. Display area, flooring, and layout

b. Benches, layout, and loading area

c. Flooring, Quonset, and benches

d. Layout, benches and flooring

3. What is the correct direction of the ridges in a greenhouse built in Missouri that allows

light to enter from the sidewalls?

a. East and west

b. North to northeast

c. South to southwest

d. North and south

List:

4. List three major considerations in determining the layout of flooring in a greenhouse

a. ________________________________________________________

b. ________________________________________________________

c. ________________________________________________________

5. List and describe three alternative types of free standing growing structures.

a. _________________________________________________________

b. _________________________________________________________

c. _________________________________________________________

6. What is an advantage and disadvantage of using glass as a covering material?

Advantage: ______________________________________________________

Disadvantage: ____________________________________________________



7. What is one advantage and one disadvantage of using rigid plastic/polycarbonate as a

covering material?

Advantage: _______________________________________________________

Disadvantage: ______________________________________________________

Matching:

The terms on the left refer to freestanding frame styles, which are picture on the right side. Write

the correct letter in the space provided.

8. _______ Quonset

9. _______ Uneven span

10. _______ Gothic arch

11. _______ A-frame

12. _______ Evan span



Greenhouse Structures Evaluation

Matching:

1. What are the basic parts of the greenhouse structure?

a. Frame and layout

b. Covering and ventilation

c. Frame and covering

d. Flooring and covering

2. What are three interior parts of a greenhouse?

a. Display area, flooring, and layout

b. Benches, layout, and loading area

c. Flooring, Quonset, and benches

d. Layout, benches and flooring

3. What is the correct direction of the ridges in a greenhouse built in Missouri that allows

light to enter from the sidewalls?

a. East and west

b. North to northeast

c. South to southwest

d. North and south

List:

4. List three major considerations in determining the layout of flooring in a greenhouse

a. Must be able to accommodate equipment and work flow

b. Must include proper drainage

c. Bare ground not acceptable

5. List and describe three alternative types of free standing growing structures.

a. Cold frames – Any one of the following answers: outdoor growing structure with

transparent covering; heated only by the sun, top opened during the day, closed at

night; used to harden and protect plants from frost, winter storage of bulbs.

b. Hotbeds – Any one of the following answers: outdoor growing structure with

transparent covering; used by steam, hot water, or electricity; used to start

seedlings or cuttings.

c. Lath houses – Any one of the following answers: outdoor growing structures

covered with lath or shade fabric supported by vertical poles; reduces light

intensity, used in summer in temperate climates or year-round in warm climates.

6. What is an advantage and disadvantage of using glass as a covering material?

a. Advantages: excellent light transmission, long lasting

b. Disadvantages: breakable, requires a heavier frame structure

7. What is one advantage and one disadvantage of using rigid plastic/polycarbonate as a

covering material?

a. Advantages: lightweight material, sturdier than film, durable

b. Disadvantages: can be damaged by the elements, must be replaced frequently



Matching:

The terms on the left refer to freestanding frame styles, which are picture on the right side. Write

the correct letter in the space provided.

8. __D____ Quonset

9. __B____ Uneven span

10. __C____ Gothic arch

11. __E____ A-frame

12. __A____ Evan span

Greenhouse Operations Management: Greenhouse Structures Notes · 2018-07-17 · Greenhouse...

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