© 2009 Autodesk Autodesk Sustainable Design Curriculum Lesson Six: Modeling the Design of...

© 2009 Autodesk

Autodesk Sustainable Design Curriculum

Lesson Six: Modeling the Design of Mechanical, Electrical, and Plumbing Systems for Sustainability

Lighting HVAC Plumbing Case Studies How to use GBS Modeling Building Energy Use

© 2009 Autodesk

Goal: Design Buildings with Minimum Carbon Footprint for a Given Program

1. Form/Footprint: Sun is the primary source of heat and light. Once built, the form is fixed for 50, 100 years.

2. Envelope: Openings and mass primary source of cooling and fresh air for ventilation. Location of openings for light and cooling/ventilation.

3. Electric lighting: Use in spaces where the natural light is insufficient and during hours where there is no sun.

4. Mechanical Ventilation: Use in conjunction with #2 when #2 is not sufficient.

5. Mechanical Cooling: When #2 is not sufficient. First stage fans (economizer), then compressorless where possible, and then compressors. Talking about displacement versus radiant versus overhead supply should be after the first items are addressed.

6. Mechanical Heating: Use when #1 is not sufficient. Heat recovery where possible.

7. Generate Energy: Power what remains with noncarbon source (photovoltaics, air and water panels, wind, hydro?, biodiesel?, nuclear? and other yet to be determined sources).

© 2009 Autodesk

Where Should Efficiency Efforts Be Concentrated?Energy Use•Varies by Building Type•Varies by Region

The architect’s design impacts the future energy use of lighting, heating, cooling, water heating, and ventilation.

The largest piece may surprise some people―lighting.

The other surprise….

Based on current LEED, ASHRAE, and Title 24 Standards, designers ignore the “other” loads that represent approximately 1/3 of the total for typical buildings, and will represent even more in an efficient building—for low carbon, all the energy should be considered.

© 2009 Autodesk

Where Should Efficiency Efforts Be Concentrated?Criteria for Modeling Electric IlluminationElectric lighting is one of the primary uses of electricity in buildings. It has been a long-standing area of focus for energy efficiency initiatives.

The desire to reduce the amount of energy used to illuminate a building must be balanced with the very real safety, productivity, and comfort criteria that professional lighting designers address.

Light can be transmitted from a light source to the eye through many different processes. Today, designers use three simple mathematical models of these processes to quickly produce efficient lighting:

• Ambient • Diffused • Specular

For those who have a strong interest in this area, other more advanced illumination models also exist. (See http://www.cs.jhu.edu/~cohen/RendTech99/Lectures/Illumination_Models.color.pdf and http://www.diva-portal.org/diva/getDocument?urn_nbn_se_liu_diva-5403-1__fulltext.pdf).

© 2009 Autodesk

Where Should Efficiency Efforts Be Concentrated?Criteria for Modeling Electric Illumination

A sustainable approach to artificial illumination maximizes natural daylight and employs lighting controls (such as photosensors and occupancy sensors) along with efficient lamps, ballasts, and fixtures to minimize energy use, while optimizing the visual experience of the building inhabitants by addressing the following criteria:

• Glare-free, well-distributed daylighting.• Illumination levels and color contrasts required in different rooms

buildings, and building types at different times of the day and year.• The need to reduce “veiling flare” (stray light that washes out contrasts).• Ambient lighting requirements for background and space definition.• Task lighting requirements for individual detail work.• Accent lighting requirements for emphasis and drama.

© 2009 Autodesk

• Saves energy.• Connects people to the outdoors.• Student performance.*• Retail sales.* • Worker productivity.*• Drastically cuts lighting costs.• Pays for itself very quickly.• Does not have to cause glare or

heat gain.

*http://www.h-m-g.com/projects/daylighting/projects-PIER.htm

Design Goal: Daylighting with Supplemental Electric Lighting Backup

© 2009 Autodesk

Direct Versus Indirect-Direct Lighting Fixtures: Mini Case Study

•30’ x 30’ classroom

•2-lamp fixtures

•T-8 lamps, 3150 lumens/lamp

•58 watts/ fixture

© 2009 Autodesk

Simulation Results

2-lamp lensed troffer

2 lamp direct-indirect

Illumination level 50.6 fc 51.2 fc

Lighting power density 1.3 W/sq. ft. 1.03 W/sq. ft.

Number of fixtures 20 16

Ratio of light to dark 5.1 4.9

Direct-indirect fixtures provide:

•Higher illumination

•Less watts

•Fewer lamps

•Narrower range of light to dark spots

ONLY FIXTURE TYPES CHANGED

With NO CHANGE in the ballasts or lamps—only fixture type—the lighting power was reduced by 30%!

© 2009 Autodesk

Real Life Success Stories - Retail

Source of Photos: Osram Sylvania Lighting

Before:3500K lampsStandard power-factor ballasts 3” deep, 12-cell parabolic lenses4-lamp fixtures 114 watts/fixture

After:4100K lamps

Low-power factor ballasts1.5” 18-cell parabolic lenses

3-lamp fixtures71 watts/fixture

© 2009 Autodesk

My Engineer Say She Cannot Beat the Lighting Requirements

Do not use the energy code as the target for your lighting energy. You can do better.

Large retail chain account has achieved LPD of 0.95 Watts/sf. Illumination Engineering Society of North America (IESNA) recommendations:

Classroom: 30 FC Retail: 50 FC

American Society of Heating, Refrigerating and Air Conditioning (ASHRAE) and CA code requirements, maximum lighting power density (LPD) for whole building: School: 1.2 watts per square foot Retail: 1.5 watts per square foot

IESNA online lighting resource: http://12.109.133.232/cgi-bin/lpd/lpdhome.pl

© 2009 Autodesk

Mechanical CoolingUse mechanical cooling only when mechanical ventilation and natural ventilation are not sufficient. Enable fans and economizers. Economizers, as the name implies, economize by saving on cooling energy costs.

Examples of cooling without compressors include evaporative cooling, dessicant cooling, and in some locations air pulled through an underground culvert. An evaporative cooler provides cooling by combining water evaporation and moving air. Fresh outside air is drawn through a moist medium; the air is cooled by evaporation and is:

• Circulated through the space directly (direct evaporative cooling); • Used as a secondary air stream to pre-cool an air-conditioning system (indirect evaporative cooling); • Or a combination of the two, called indirect-direct or IDEC evaporative cooling.

The temperature of the outside air can be lowered by up to 30° F. Evaporative coolers are very effective as long as the outside air is dry enough. However, the capacity for evaporative cooling decreases as the humidity of the outdoor air increases. Newer two-stage, or indirect/direct evaporative cooling systems, can provide cooling well beyond the thresholds of the traditional “swamp coolers” used in the past.

The cooling stage of “last resort” is use of air-conditioning compressors. The supply air cooled by the compressors can be distributed in ways that also impact the energy consumption of the building. Fans can use a great deal of energy, and some distribution systems minimize the fan energy better than others. This includes under-floor and displacement systems that take advantage of the buoyancy of warm air and in some cases provide occupants with control over the air flow in their own space.

Use mechanical cooling only when mechanical ventilation and natural ventilation are not sufficient. Enable fans and economizers. Economizers, as the name implies, economize by saving on cooling energy costs.

Examples of cooling without compressors include evaporative cooling, dessicant cooling, and in some locations air pulled through an underground culvert. An evaporative cooler provides cooling by combining water evaporation and moving air. Fresh outside air is drawn through a moist medium; the air is cooled by evaporation and is:

• Circulated through the space directly (direct evaporative cooling); • Used as a secondary air stream to pre-cool an air-conditioning system (indirect evaporative cooling); • Or a combination of the two, called indirect-direct or IDEC evaporative cooling.

The temperature of the outside air can be lowered by up to 30° F. Evaporative coolers are very effective as long as the outside air is dry enough. However, the capacity for evaporative cooling decreases as the humidity of the outdoor air increases. Newer two-stage, or indirect/direct evaporative cooling systems, can provide cooling well beyond the thresholds of the traditional “swamp coolers” used in the past.

The cooling stage of “last resort” is use of air-conditioning compressors. The supply air cooled by the compressors can be distributed in ways that also impact the energy consumption of the building. Fans can use a great deal of energy, and some distribution systems minimize the fan energy better than others. This includes under-floor and displacement systems that take advantage of the buoyancy of warm air and in some cases provide occupants with control over the air flow in their own space.

© 2009 Autodesk

Mechanical HeatingUse mechanical heating systems when the building form/footprint does not allow sufficient passive solar heating. Use heat recovery systems where possible and provide heat in a form that is most useful to occupants. This can include radiant or convective heating, or a combination.

Heating Equipment • Solar collectors. • Furnaces (air heaters).• Heat pumps.• Boilers (water heaters/steam).• Infrared radiant heaters (gas/electric) – Electric radiant heaters can be very expensive

unless the climate is mild.• Electric heaters.

Cooling Equipment• Heat rejection equipment. • Direct Expansion (DX) units, typically called RTUs (rooftop units) or packaged units,

depending on the region.• Chillers – In large buildings, the equipment used to produce cool water is called a chiller.

The cool water is pumped to air handling units to cool and dehumidify the air.• In the U.S., the capacity of cooling equipment is typically measured in tons. One ton of

cooling is equal to the amount of cooling that occurs when one ton of ice melts in 24 hours. One ton of cooling = 12,000 Btu/hr. A window wall air conditioner provides approximately one ton of air conditioning.

Use mechanical heating systems when the building form/footprint does not allow sufficient passive solar heating. Use heat recovery systems where possible and provide heat in a form that is most useful to occupants. This can include radiant or convective heating, or a combination.

Heating Equipment • Solar collectors. • Furnaces (air heaters).• Heat pumps.• Boilers (water heaters/steam).• Infrared radiant heaters (gas/electric) – Electric radiant heaters can be very expensive

unless the climate is mild.• Electric heaters.

Cooling Equipment• Heat rejection equipment. • Direct Expansion (DX) units, typically called RTUs (rooftop units) or packaged units,

depending on the region.• Chillers – In large buildings, the equipment used to produce cool water is called a chiller.

The cool water is pumped to air handling units to cool and dehumidify the air.• In the U.S., the capacity of cooling equipment is typically measured in tons. One ton of

cooling is equal to the amount of cooling that occurs when one ton of ice melts in 24 hours. One ton of cooling = 12,000 Btu/hr. A window wall air conditioner provides approximately one ton of air conditioning.

© 2009 Autodesk

Air Distribution EquipmentThe conditioned air is typically delivered with fans pushing the air through ductwork or under the floor and through diffusers. Moving a large mass of air at low speed is a far more efficient than pushing air through small ducts at high speed.

Constant Air Volume systems deliver a constant flow of air while varying the temperature of the supply air.

• Variable Air Volume (VAV) systems vary the amount of air supplied to a zone while holding the supply air temperature constant.

• Under-floor air distribution delivers air low in the space, at low velocity and pressure drop, and relatively high temperature compared to traditional ceiling delivery systems that deliver a blast of 55° F air from above. This system type has the potential to save energy with both reduced fan energy and warmer supply air (reduced HVAC loads), and to provide a high degree of individual comfort control.

• Displacement ventilation relies primarily on the buoyancy of warm air rather than fans to move air.

• Radiant heating provides space heating by circulating heated water or steam through radiators in the room or tubing embedded in the floor.

• Chilled beams provide space cooling by circulating cool water through exposed tubes in the ceiling.

The conditioned air is typically delivered with fans pushing the air through ductwork or under the floor and through diffusers. Moving a large mass of air at low speed is a far more efficient than pushing air through small ducts at high speed.

Constant Air Volume systems deliver a constant flow of air while varying the temperature of the supply air.

• Variable Air Volume (VAV) systems vary the amount of air supplied to a zone while holding the supply air temperature constant.

• Under-floor air distribution delivers air low in the space, at low velocity and pressure drop, and relatively high temperature compared to traditional ceiling delivery systems that deliver a blast of 55° F air from above. This system type has the potential to save energy with both reduced fan energy and warmer supply air (reduced HVAC loads), and to provide a high degree of individual comfort control.

• Displacement ventilation relies primarily on the buoyancy of warm air rather than fans to move air.

• Radiant heating provides space heating by circulating heated water or steam through radiators in the room or tubing embedded in the floor.

• Chilled beams provide space cooling by circulating cool water through exposed tubes in the ceiling.

© 2009 Autodesk

Built Up Systems

Typically use chilled water (CHW) and hot water (HW) instead of refrigerant to move heat to central air handlers that contain the fans, economizers, cooling and heating coils, and dampers.

Chillers supply the chilled water.

Cooling towers that supply condenser water (CW) to the chiller are used instead of the air condensers as found on most DX equipment.

Boilers typically supply the HW (can be steam from district heating).

Typically contain CHW, HW, and CW loops along with piping, pumps, and controllers.

© 2009 Autodesk

Chillers/ Chilled Water LoopsComponents•Chillers

•Centrifugal – large/efficient•Screw – part load operation•Reciprocating – small/cheap•Absorption – Gas/steam powered

• Many different piping/pumping options. Older chillers typically require constant volume water flow. Newer chillers tolerate variable flow well, saving on pumping energy at low loads.

Characteristics•~2.0 – 3 gpm of CHW per ton of chiller capacity•Efficiencies and Capacities

•Centrifugal ~150 – 10,000 tons, 0.45 – 0.70 kW/ton•Screw ~100 – 300 tons, 0.6 – 0.8 kW/ton•Reciprocating ~ 25 – 150 tons, 0.85 – 1.2 kW/ton, typically integrated air side condensers.

•Old chillers typically used R11, R12 CFC refrigerants. Newer chillers use 134a and others.

Air Handling Unit 1 (AHU)

\

Air Handling Unit 2 (AHU)

© 2009 Autodesk

Water and Energy EfficiencyWhile climate change awareness has led to an important movement toward more energy efficient buildings, it is essential that an energy efficient design also incorporate Water conservation measures. Why?

Although it may not be front-page news, there is a critical relationship between water, energy, and global warming. We are all familiar with efficient water-using appliances such as washing machines. However, even toilets and irrigation systems consume electricity, but because that usage does not show up on the electric meters in our homes and offices it is easy to ignore.

Based on recent research done in California, it is estimated that approximately 19% of the state’s electricity and an even higher percentage of its natural gas is used to acquire, treat, and convey water to end-users.

Clearly saving water also saves energy, although the connection is not intuitive to most people.

© 2009 Autodesk

Water Conservation StrategiesIn light of these increased demands for fresh water, sustainable designers frequently rely on plumbing engineers to implement water conservation and recycling strategies into the design of building plumbing systems. Water conservation strategies for indoor systems typically rely on modeling use rates (that is, flushes per person per day), flow rates (in gallons per minute), and the number of persons in the facility.

Water conservation solutions usually specify low-flow fixtures and on-demand water heaters. For outdoor irrigation systems, a water budget is used to calculate the amount of water that a landscape needs, taking into account the inputs and outputs of water to and from the root zone. Inputs, such as precipitation, are subtracted from outputs, such as evapotranspiration, to calculate the water needs of the landscape.

Many factors are taken into consideration when calculating a water budget, such as plant type and irrigation system efficiencies. The water budget establishes a baseline of how much the owner should expect to use in the building, where the water goes, and when it is used.

© 2009 Autodesk

Onsite Renewable EnergyPhotovoltaic (PV) panels convert between 5% and 20% of the incident solar energy into electricity.

Wind turbines have an average efficiency of 35%.

PV and wind systems use an inverter to convert the direct current electricity from the panels or turbines into alternating current that can be used in most buildings, and can be “inter-tied” to the larger power grid. In remote locations, a battery system can be used to store power. It does not typically make sense to store energy in batteries if the project is in an urban or suburban location because of the high cost of batteries, relative to the low cost of power supplied by the grid during the ”off peak” demand nighttime hours.

General rules of thumb for renewable energy systems:

• Incorporate PVs as part of the shading systems of the building.• Use wind power when available and appropriate to the site.• It is almost always cheaper to use skylights to light a space than photovoltaic

panels or a wind turbine to power an inefficient lighting system.

© 2009 Autodesk

Modeling the Design of Plumbing Systems for Sustainability

It has become common knowledge in the AEC community that global water supplies are coming under increasing pressure.

Only 3% of the world’s water is fresh and less than a third of 1% of this is available to humans. Many models of global climate change include increased incidence of drought.

When sustainable designers turn their attention to the design of plumbing systems, it becomes even clearer how important fresh water is to every aspect of a building’s design, construction, and operation.

The challenge of sustainability for the modeling of plumbing systems requires an added awareness of the importance of water conservation, because potable water is increasingly being used for many other purposes besides just drinking, bathing, and conveying sewerage.

© 2009 Autodesk


Plumbing for “Green” Roofs and Rainwater Catchment Systems

Plumbing for “Green” RoofsGreen roofs usually require permanent irrigation systems that are similar to site irrigation systems. These systems are designed and installed by an irrigation system provider, so it is important to coordinate a green roof’s layout with the irrigation system design. A water budget is used to calculate the amount of water that a landscape needs.

Plumbing for Rainwater CatchmentThe integration of rainwater catchment from roof areas is another rapidly expanding area of design innovation. Plumbing engineers are being called upon to help model and implement strategies for sizing catchment storage tanks (with respect to local precipitation, system demand, dry periods during the year, and the roof area), and dealing with environmental pollutants such as dust, twigs, leaves, and bird/animal droppings.

© 2009 Autodesk


Plumbing for Water Source Heat PumpsEnergy efficiency goals have made water source heat pumps much more attractive to building owners, designers, and builders because they are extremely efficient technologies for heating and cooling spaces.

The best models extract 5 kWh of heat from the water loop for every 1 kWh of electricity used to power the compressor and fan, delivering all 6 kWh as heat into the air. This 6-to-1 ratio is called the COP (Coefficient of Performance), and can be equated to a 600% efficiency level. By comparison, the very best fossil fuel furnaces and boilers produce heat at less than 100% efficiency.

A high-efficiency chiller is typically 10 to 15% less efficient than a water source heat pump (TET) system, operationally, while a standard chiller performs 30 to 50% less efficiently.

(John Vastyan, 2009 “Thermal Energy Transfer to Commercial Building Efficiency,” TMB Plumbing Engineer. http://www.plumbingengineer.com/july_09/vastyan_feature.php)

© 2009 Autodesk

Case Study: Municipal Office

• 30,000 sq. ft. municipal office in Santa Clarita.• Strawbale construction.• Reduced the cooling system size by 50%.• Half the building is daylit – high performance glass +

skylights.• Lighting system has 60% of “Title 24” Watts.• Raised floor “displacement” cooling.• Exceeded T24 Standard by approximately 45%.

Except for the strawbale construction, the efficiency upgrades were paid for by the reduction in number of cooling units and a reduced number of lighting fixtures.

© 2009 Autodesk

Case Study – Southern California Office Building

Highlights:•Skylights 1st and 2nd Floor with chase.

•Lighting at 40% of T24 (0.5 W/sq. ft.).

•LED task lighting (0.05 W/sq. ft.).

•Shading of glass for visual comfort.

•Cooling system size reduced 30%.

•Energy Use – reduced 35% (50% if “plug” loads are counted).

•PV’s power approximately 50% of the rest.

•LEED Platinum applied for.

© 2009 Autodesk

$3,418

$40,000 $50,000 $60,000 $70,000 $80,000 $90,000 $100,000

Alt 0Alt 1Alt 2Alt 3Alt 4Alt 5Alt 6Alt 7Alt 8Alt 9

Alt 10Alt 11Alt 12Alt 13Alt 14Alt 15Alt 16Alt 17Alt 18Alt 19Alt 20Alt 21Alt 22Alt 23Alt 24Alt 25Alt 26Alt 27Alt 28Alt 29Alt 30Alt 31Alt 32Alt 33Alt 34Alt 35Alt 36Alt 37Alt 38Alt 39Alt 40Alt 41Alt 42Alt 43Alt 44

Electric Cost Gas Cost

Title 24

Varying Insulation, Thermal Mass

Raise sill ht. 1'

Varying Glazing Characteristics

Light Shelves for Daylighting

Building Shades - varying size

Add'l Skylights and Controls

Lighting, Task Lighting, Occ Sensors

Very Efficient Central Plant

Alt 36 -UFAD Bad Results

Enhance Pkg HVAC with Evap Condenser + IDEC

Natural VentilationNight Flush Ventilation

Combination Packages A, B, C

Energy Star Plug Loads

Approx. 70 tons of peak cooling - Alts 42 - 44

Approx. 100 tons of peak cooling for baseline building

Prelim. Design + Skylt + Ctrls Whole Building Energy Analysis Results:

•Top line, Energy Code Baseline, nearly $90,000 annually.

•Bottom three bars, combination of energy efficiency measures, approximately $45,000 annually. Half of the baseline!

•Not all energy saving measures “count” for regulatory purposes (for example natural ventilation), but all measures should be considered when designing for carbon neutrality.

Case Study – Southern California Office Building

© 2009 Autodesk

Schematic Designs in Autodesk® Green Building Studio® Web Service (GBS) If the change is a change in form, make the change in the BIM

tool. Building footprint Adding, moving glazing/skylights, Changes in floor plan Adding shading surfaces/shading studies with sun position

If the change is a technology, equipment, or component, make the change in GBS. Glazing properties (heat gain, transparency, and so on) Lighting and lighting controls Insulation levels Quantifying energy impacts of shading HVAC type and efficiency

© 2009 Autodesk

Step 4: Exporting to the Green Building Studio Web Service from the Revit® Family of Products

Step 1: Under the Room and Area Design Bar, select the Settings icon to open the Room and Area Settings dialog box. Select the Compute Room Volumes check box.

Step 2: Specify a zip code for your building’s location and the building type under the Settings|Project Information menu and gbXML Settings Parameter menu.

Step 3: Select the Green Building Studio Client menu item under the Tools|External Tools menu.

© 2009 Autodesk

Step 5: Login to Autodesk Green Building Studio Client

Log in

Choose a Project

Get Results

© 2009 Autodesk

Step 6: GBS Run Begins

If everything with your model is correct, a browser window will open, presenting you with the status of your Green

Building Studio energy analysis.

If everything with your model is correct, a browser window will open, presenting you with the status of your Green

Building Studio energy analysis.

© 2009 Autodesk

Step 7: View Results

Most runs complete within minutes. Large models (with gbXML files over 8 MB) may take up to an hour to run. Once your run is complete, you will see a screen similar to the one above.

Most runs complete within minutes. Large models (with gbXML files over 8 MB) may take up to an hour to run. Once your run is complete, you will see a screen similar to the one above.

© 2009 Autodesk

Steps to Running Design Alternatives

1. Select a tab of interest, and make change in drop-down list; in this case, changing to PPG glass.

2. Make additional changes as desired.

3. Give alternative a name “PPG Glass.”

4. Click the #3 button.

5. Repeat as desired.

6. Click the #4 button.

© 2009 Autodesk

Look at the Results

Start at the run list.

Good place to see how much gas/electric/fuel is consumed and its cost, across alternatives.Export to Excel if desired.

Select an alternative to look at in detail. Click the run name.

© 2009 Autodesk

Which Changes Had the Most Impact?•Form/Footprint•Envelope Construction•Glazing Type/Amount/Shading•Daylighting•Lighting•HVAC

Which metric of “impact” is emphasized?•Carbon•Money•kWh/therm/gallon of fuel oil

© 2009 Autodesk

What Happens – Measure by Measure

Energy Use by Alternative

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000

Ltg + Insul + Daylt + Glass + Eff RTU

E + All + Triple Pane

Ltg + Insul + Daylt + Glass + HVAC

E + XL70 + Day + Low LPD

Ltg + Insul + Daylt + Glass

Box + All Measures

E Shape + XL70 + Daylight

E Shape + PPG XL70

E Shape + Hi Roof Insul

GBS Training ofc E-Shape multizone pb.xml

E Shape + Hi R+W Insul

GBS Training ofc box multizone_pb.xml

Annual Electricity

0.0 50.0 100.0 150.0 200.0 250.0 300.0

Annual Fuel

AnnualElecUse AnnualFuelUse

© 2009 Autodesk

Modeling Building Energy Use with DOE-2

DOE-2 is a widely used freeware building energy analysis program that engineers can use to predict energy use and cost. Because it is scientifically rigorous and open to inspection, DOE-2 has been chosen to develop many different state, national, federal, and international building energy-efficiency standards, including:

• The ASHRAE-90.1 standard for commercial buildings, which is based on thousands of DOE-2 analyses for different building types and climates. This standard is mandatory for new federal buildings, and has been adopted by many states for nonfederal buildings.

• The ASHRAE-90.2 standard for residential buildings, which is based on 10,000 DOE-2 analyses.

• The State of California standard for commercial buildings (Title 24). • Standards for other countries such as Hong Kong, Saudi Arabia, Kuwait,

Singapore, Malaysia, Philippines, India, Indonesia, Thailand, Switzerland, Brazil, Canada, Mexico, and Australia.

DOE-2 is a widely used freeware building energy analysis program that engineers can use to predict energy use and cost. Because it is scientifically rigorous and open to inspection, DOE-2 has been chosen to develop many different state, national, federal, and international building energy-efficiency standards, including:

• The ASHRAE-90.1 standard for commercial buildings, which is based on thousands of DOE-2 analyses for different building types and climates. This standard is mandatory for new federal buildings, and has been adopted by many states for nonfederal buildings.

• The ASHRAE-90.2 standard for residential buildings, which is based on 10,000 DOE-2 analyses.

• The State of California standard for commercial buildings (Title 24). • Standards for other countries such as Hong Kong, Saudi Arabia, Kuwait,

Singapore, Malaysia, Philippines, India, Indonesia, Thailand, Switzerland, Brazil, Canada, Mexico, and Australia.

© 2009 Autodesk

Modeling Building Energy Use with DOE-2

It is important to note that the DOE-2 Weather Data Library (consisting of hourly values of outside dry-bulb temperature, wet-bulb temperature, atmospheric pressure, wind speed and direction, cloud cover, and, in some cases, solar radiation) was originally based on data from only 60 U.S. weather stations.

Autodesk Green Building Studio (GBS) tool uses the DOE-2 engine, and provides even more enhanced weather data, which includes 55,000 + virtual weather stations, 231 TMY2 stations, and 16 California Climate Zone (CCZ) stations.

GBS virtual station data was derived using two weather models: the Rapid Update Cycle (RUC) and Mesoscale Meteorological Model version 5 (MM5).

It is important to note that the DOE-2 Weather Data Library (consisting of hourly values of outside dry-bulb temperature, wet-bulb temperature, atmospheric pressure, wind speed and direction, cloud cover, and, in some cases, solar radiation) was originally based on data from only 60 U.S. weather stations.

Autodesk Green Building Studio (GBS) tool uses the DOE-2 engine, and provides even more enhanced weather data, which includes 55,000 + virtual weather stations, 231 TMY2 stations, and 16 California Climate Zone (CCZ) stations.

GBS virtual station data was derived using two weather models: the Rapid Update Cycle (RUC) and Mesoscale Meteorological Model version 5 (MM5).

© 2009 Autodesk

Modeling Building Energy Use with EnergyPlusEnergyPlus is a next-generation, freeware building energy simulation program based on DOE-2 and BLAST, another sophisticated energy analysis program. EnergyPlus has numerous added capabilities.

EnergyPlus models heating, cooling, lighting, ventilating, and other energy flows, as well as water in buildings. While originally based on the most popular features and capabilities of BLAST and DOE-2, EnergyPlus includes many innovative simulation capabilities, such as:

• Time steps of less than an hour • Modular systems and plants integrated with heat balance-based zone simulation • Multizone air flow • Thermal comfort • Water use • Natural ventilation• Photovoltaic systems

EnergyPlus is a stand-alone simulation program. It lacks a user-friendly graphical interface. EnergyPlus reads input and writes output as text files. A number of graphical interfaces are available or under development. See http://www.eere.energy.gov/buildings/energyplus/ for more information.

EnergyPlus is a next-generation, freeware building energy simulation program based on DOE-2 and BLAST, another sophisticated energy analysis program. EnergyPlus has numerous added capabilities.

EnergyPlus models heating, cooling, lighting, ventilating, and other energy flows, as well as water in buildings. While originally based on the most popular features and capabilities of BLAST and DOE-2, EnergyPlus includes many innovative simulation capabilities, such as:

• Time steps of less than an hour • Modular systems and plants integrated with heat balance-based zone simulation • Multizone air flow • Thermal comfort • Water use • Natural ventilation• Photovoltaic systems

EnergyPlus is a stand-alone simulation program. It lacks a user-friendly graphical interface. EnergyPlus reads input and writes output as text files. A number of graphical interfaces are available or under development. See http://www.eere.energy.gov/buildings/energyplus/ for more information.

© 2009 Autodesk

CommissioningGreen building measures cannot achieve their goals unless they work as intended. The best way to determine whether a building is working as intended is by a process called “commissioning.” Building commissioning includes testing and adjusting the envelope, mechanical, electrical, and plumbing systems to ensure that all equipment works and operates according to design criteria.

What Do You Get Without Commissioning?A study of 60 commercial buildings found that more than half suffered from control problems.

• 40% had problems with HVAC equipment. • 1/3 had sensors that were not operating properly.• 15% had missing specified equipment.• Approximately 1/4 of them had energy management control systems (EMCS),

economizers, and/or variable speed drives that did not run properly.

Benefits of Commissioning• Increase in energy efficiency.• Improved performance of building equipment and systems.• Improved IAQ, occupant comfort, and productivity.• Decreased potential for building owner liability related to IAQ problems.• Reduced operation and maintenance costs.

Green building measures cannot achieve their goals unless they work as intended. The best way to determine whether a building is working as intended is by a process called “commissioning.” Building commissioning includes testing and adjusting the envelope, mechanical, electrical, and plumbing systems to ensure that all equipment works and operates according to design criteria.

What Do You Get Without Commissioning?A study of 60 commercial buildings found that more than half suffered from control problems.

• 40% had problems with HVAC equipment. • 1/3 had sensors that were not operating properly.• 15% had missing specified equipment.• Approximately 1/4 of them had energy management control systems (EMCS),

economizers, and/or variable speed drives that did not run properly.

Benefits of Commissioning• Increase in energy efficiency.• Improved performance of building equipment and systems.• Improved IAQ, occupant comfort, and productivity.• Decreased potential for building owner liability related to IAQ problems.• Reduced operation and maintenance costs.

© 2009 Autodesk

SummaryModeling the performance of mechanical, electrical, and plumbing systems is an essential step in the sustainable design process.

Optimizing the design of each of these systems so that they interact in a mutually reinforcing manner, with respect to the flow of heat and the consumption of energy and water, enables architects and MEP engineers to achieve sustainable design goals and to fine-tune whole building performance.

Modeling the performance of mechanical, electrical, and plumbing systems is an essential step in the sustainable design process.

Optimizing the design of each of these systems so that they interact in a mutually reinforcing manner, with respect to the flow of heat and the consumption of energy and water, enables architects and MEP engineers to achieve sustainable design goals and to fine-tune whole building performance.

© 2009 Autodesk

Autodesk, Green Building Studio and Revit are registered trademarks or trademarks of Autodesk, Inc. and/or its subsidiaries and/or affiliates, in the USA and/or other countries. All other brand names, product names, or trademarks belong to their respective holders. Autodesk reserves the right to alter product offerings and specifications at any time without notice, and is not responsible for typographical or graphical errors that may appear in this document.

© 2009 Autodesk, Inc. All rights reserved.

© 2009 Autodesk Autodesk Sustainable Design Curriculum Lesson Six: Modeling the Design of...

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