Energy Conservation Measures

This page includes lists of potential energy conservation measures (ECMs) intended to serve as a source of inspiration when brainstorming appropriate ECMs.

Architecture

ECM	Comments
Separate vision and daylighting windows	Optimize the glazing selection separately for the upper (daylight) and lower (vision) portions of the windows. Choose daylight glazing for good daylight distribution and vision glazing to balance views and glare. Most beneficial if combined with lightshelf or light louver to control glare from upper window or with separate interior mini blinds for upper (daylight) portion of window.
Spectrally selective low-e glazing	Choose optimal combinations of solar heat gain (SHGC) and visible light transmittance (VLT) to minimize cooling load and optimize visual environment.
Exterior shading – overhang	Size overhang to eliminate direct solar radiation if possible, reducing cooling load and glare. Account for window cleaning, birds.
Exterior shading – sidefin	Size overhang to eliminate direct solar radiation, reducing cooling load and glare. Account for window cleaning.
Exterior shading – screen or louver	Design shades to block direct sun. Also generally desirable to bounce light up onto ceiling for better daylight distribution. Account for window cleaning. Can be fixed position, manually operable or automatically operable.
Light shelf	Distributes daylight deeper into the perimeter zone and provides shading to help reduce heat gain and control glare close to the window.
“Lightlouver”	Proprietary product that mounts inside the upper window and redirects light up to the ceiling to improve the depth of daylight distribution.
Interior shades	Roller shades or venetian blinds on the vision glass help to control glare. Can be manually or automatically operated.
Thermally broken window frame / curtainwall	Reduce winter heat loss and summer heat gain by avoiding metal thermal bridges. Can also improve the comfort of occupants close to the windows.
Optimized glazing area	Use simulation to determine the optimal range of glazing area that provides adequate daylighting while minimizing solar heat gain.
Glazing orientation	Orient windows north or south, where solar gain is relatively easy to control. Minimize west and east glazing, where direct sun is hard to control.
Double-wall facade	Typically a second skin of glass that creates a buffer zone up to several feet deep.
Operable ventilation openings	Provide the occupants with access to outdoor air. In many climates this can reduce overall energy consumption. Requires coordination with mechanical design. May increase the range of acceptable comfort conditions (ASHRAE 55-2004).
Cool roof	A reflective roof membrane reduces cooling loads. Typically white, may be a single ply membrane, liquid applied coating, or coated metal. Must have a high emissivity as well as high reflectance. If color is desired, then consider new metal coatings that have similar visual properties to traditional coatings yet have higher solar reflectance.
Vegetated roof	Provides additional insulation as well as reducing stormwater runoff rate.
Light colored wall exterior surface	Use light-colored, preferably white, exterior surfaces in warm climates to reduce cooling load. Ensure high emissivity as well as high reflectance.
Reflective interior surfaces	The interior space design can greatly affect the amount of light required to provide adequate illumination.  Use of light colors and fewer and lower partitions in the space design can result in increased lighting efficiency.
Increase ceiling and window height at perimeter	Higher windows increases the depth of daylight penetration.
Increase ceiling height	Higher windows increases the depth of daylight penetration. Higher ceiling improves the performance of underfloor air distribution by allowing temperature stratification to occur.
Eliminate ceiling	Higher windows increases the depth of daylight penetration. Higher ceiling improves the performance of underfloor air distribution by allowing temperature stratification to occur. May reduce total material use. Account for acoustics.
Space planning to maximize daylighting potential	Locate regularly occupied spaces in daylighted zones. Move circulation to interior, where lower illumination levels may be acceptable.
Space planning to minimize solar heat gain	Locate service space such as mechanical/electrical rooms, toilets, and stairwells at the west and/or east orientations.
Space planning for improved comfort	Locate circulation at perimeter, with relaxed comfort criteria for air temperature, mean radiant temperature, and glare. (Example: USGBC office, Washington D.C.)
Optimum building envelope insulation levels	Use simulation results to select economically optimal levels of insulation.
Thermal mass	Concrete or other dense material within the building can delay and reduce peak cooling load,
Infiltration reduction	Envelope sealing and attention to minimizing window and door leakage can reduce heating and cooling loads in perimeter zones.
Highly insulated enclosure	Avoid installation of separate perimeter heating system with highly insulated windows and walls.

Electric Lighting

ECM	Comments
Efficient lighting design	Minimize lighting power requirement through luminaire selection and layout.
High efficiency luminaires	Specify luminaires with a high coefficient of utilization to minimize lighting power requirement.
Efficient task lighting	LED task lighting
Daylight dimming controls	Dimming LED drivers with photocell control.
Pendant-mounted indirect or direct/indirect luminaires	Indirect light reflecting from the ceiling provides even, relatively glare-free illumination and helps a space to feel brighter.
Occupancy sensor control - private office	Motion sensor control for lighting.
Occupancy sensor control - open office	Motion sensor control for lighting.
Occupancy sensor control - restrooms	Motion sensor control for lighting.
Occupancy sensor control - misc spaces	Motion sensor control for lighting.
Task lighting occupancy sensor control	Motion sensor control for lighting.
Efficient garage lighting
LED exterior lighting

Mechanical - Air-side

ECM	Comments
High efficiency cooling equipment	Specify packaged cooling equipment with high full-load and part-load efficiency.
Select air filters for low pressure drop	Consider both initial and final (loaded) pressure drop ratings.
Maximize air filter face area	Take advantage of all available space to maximize the area of filters within the air handler, reducing air velocity (face velocity) and therefore reducing pressure loss.
Low face-velocity coils	Select heating and cooling coils to minimize air pressure loss.
Bypass dampers	Provide dampers that allow air to bypass the cooling and heating coils when the coils are not active in order to reduce air pressure loss.
Return air shaft sizing	Maximize shaft cross-sectional area to minimize air pressure loss.
Duct sizing	Choose larger ducts for lower pressure loss.
Duct fittings	Choose efficient fittings for lower pressure loss, such as larger radius turns or bends with turning vanes.
Efficient duct layout	Minimize the number of turns and other fittings.
Demand control ventilation	Minimize outdoor air ventilation flow based on measurements of room CO2 concentrations as a proxy for occupancy.
Duct sealing	Duct leakage can be significant and cause excess fan energy as well as wasted heating or cooling energy.
Evaporative cooling of ventilation air	Pre-cool outdoor air to reduce peak chiller load during hot weather and to reduce chiller run hours during mild conditions.
Outdoor air economizers	Use 100% outdoor air for cooling whenever outdoor air is cooler than return air.
Efficient fan selection	Carefully select fans for maximum efficiency in the expected operating conditions for air flow and pressure.
Housed fans rather than plenum-type fans	Housed fans generally need more space than plenum fans because a straight length of duct is required at the discharge of the fan, but housed fans are generally more efficient.
Static pressure reset controls	Dynamically reset the static pressure setpoint for the supply fan based on zone damper demand.
Supply air temperature control via chilled water temperature reset	In a system with a single large cooling coil, consider controlling the supply air temperature by varying the chilled water temperature rather than (or in sequence with) varying flow through the coil. Chillers typically operate more efficiently with higher chilled water temperatures. Determine an optimal control scheme that balances chiller energy and pump energy.
Supply air temperature reset control	Control supply air temperature in a VAV system to minimize combined cooling, fan, and reheat energy.
Sequenced economizer dampers	Outside air dampers and return air dampers are sequenced rather than modulated simultaneously to reduce pressure loss during periods when the system is calling for somewhere between 100% and minimum outside air.
Return air via space or plenum rather than ducted return	Minimize fan energy required for return air by avoiding a ducted return air path where possible.
Optimal air handler layout	Minimize air pressure loss by allowing adequate area for filters and coils and by paying attention to fan inlet and discharge conditions to avoid system affect losses.
Mixed mode ventilation	Consider integrating natural ventilation and mechanical ventilation.
Displacement ventilation	Deliver air at low level and at moderate temperature, typically about 65°F and remove at ceiling level.
Dual-fan, dual-duct system	Separate cooling and heating air handlers and ducts serve variable-volume mixing boxes at each zone. The heating duct typically recirculates return air and significantly reduces reheat energy consumption compared to a single-duct VAV system. May require extra space for ducts.
VAV box – dual maximum control sequence	Set minimum air flow setpoint based on minimum ventilation requirement, and set separate maximum flow setpoints for cooling and for heating. Limit discharge temperature in heating mode to about 90°F.
Chilled-beam cooling delivery
Dedicated outdoor air system
Water-source heat pumps	May be ground-coupled.
Indirect/direct evaporative cooling	Use evaporative cooling to meet some or all of cooling loads in climates where humidity is low during warm weather. An indirect evaporative stage followed by a direct evaporative stage can produce relatively low supply air temperatures.
Night-flush cooling cycle	Run fans at night when free cooling is available to pre-cool the building and reduce peak cooling load during the day. Careful attention to controls is required to avoid creating morning warmup penalty.
Heat recovery	Several options available including air-to-air heat exchangers, heat pipe, run-around coil, or heat wheel.

Mechanical - Water-side

ECMs	Comments
Thermal energy storage for cooling	Chilled water or ice storage to reduce or eliminate chiller electric demand during peak cooling periods.
Variable-speed chiller	Specify chillers with variable speed compressor to provide significant efficiency improvement at partial load conditions.
High-efficiency chiller	Select a chiller with maximum efficiency in the expected operating range.
Select chiller size(s) for efficient staging
Low-approach cooling tower	Select a tower that can produce cooler leaving water temperatures – targeting no more than 7°F higher than the design wetbulb temperature.
Variable-speed cooling tower fan
Variable-speed condenser water pump control
Efficient cooling tower	Select a tower designed to minimize fan power.
Primary-only, variable flow chilled water pumping	Can be lower first cost and more efficient as well, compared to a primary/secondary pumping arrangement.
Chilled water pump pressure differential reset	For variable flow systems, reset the pressure differential setpoint (which is used to control the speed) based on the chilled water control valve that is “most open”, with the intent that it should be at least 90% open.
Chilled water temperature reset	Employ a control scheme that increases the chilled water temperature under low-load conditions in order to improve chiller efficiency.
Condenser water temperature reset	Lower the condenser water setpoint during mild conditions to improve chiller efficiency.
High chilled water delta T	Select cooling coils for at least a 15°F difference between entering and leaving chilled water in order to minimize flow and pumping energy.
Efficient coil selection	Minimize water pressure drop and air pressure drop through the coil.
Efficient piping layout	Minimize the number of fittings. Consider increasing pipe sizes to reduce pressure loss.
Two-way valves on heat pumps (condenser water loads)	Shut off condenser water flow through the heat pump condenser whenever the heat pump compressor is not running.
Variable flow hot water distribution	Variable speed control of hot water pumps and two-way valves on hot water coils.
Water-side free cooling (economizer)	Use cooling tower to provide chilled water during cool weather. Typically use a plate and frame heat exchanger.

Receptacle Loads

ECM	Comments
Efficient office equipment

Additional Resources

• EnergyStar list of existing building ECMs

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