Energy Efficiency Guide for Colorado Businesses
Recommendations by Sector
LARGE OFFICE BUILDINGS
Energy Use
There is only a rough-and-ready distinction between small and large office buildings, but the demarcation line used here is around 50,000 square feet. The principal energy uses in most large office buildings are divided about evenly between lighting, HVAC, and plug loads. Since lighting, plug loads, people, and solar all provide heat that must be removed by the building's cooling system, many large office buildings are in the cooling mode for most of the year, particularly during periods of substantial occupancy. Retrofit measures that improve the efficiency of lighting and office equipment, as well as those that improve windows and shading, can lower the demand on the cooling system. Combined with such retrofits, oftentimes an energy-efficient new chiller can be installed that is substantially downsized from the old one. This can result in both initial and life-cycle savings that are quite substantial.
Measures that are often found to be very cost-effective include the following:
High-efficiency Lighting
- Replace T-12 fluorescent fixtures with T- 8 or T-5 fixtures with electronic ballasts.
- Install and adjust automatic dimming controls to take advantage of daylighting. The “Cool Daylighting” approach keeps most outside light out of view, thereby controlling for glare, producing better distribution, and lowering cooling costs (see http://www.daylighting.org/what_is_cool_daylighting.htm).
- Install and adjust occupancy controls.
- Install LED exit signs.
- Upgrade parking lot lighting to save energy and reduce the environmental impacts associated with lighting the sky instead of the parking lot.
High-efficiency HVAC
- Install a water-cooled chiller.
- Downsize to a new high-efficiency chiller in the light of lighting and other retrofits.
- Use condensing boilers with large turn-down ratios whose efficiencies improve with turn-down.
- Switch over to direct digital controls.
- Install variable air volume air handling systems with variable speed drives.
- Install premium-efficiency motors.
- Install demand-controlled ventilation.
- Ventilate garages in response to environmental conditions.
- Upgrade the energy management system; optimize settings to reflect usage, respond to changing weather patterns, and control peak electric loads.
- Continuously commission the building.
- Verify economizer function and control.
- Consider using cool air from the cooling tower with water-cooled chillers.
- Consider indirect-direct evaporative cooling.
Combined Heat and Power (CHP) System
- Install a combined heat and power generation system to supply electricity, heating needs, and (through an absorption chiller) cooling needs. When properly sized and designed, such a system can save substantial money and avoid the large thermal losses associated with conventional power generation at utility plants.
Building Envelope
- Install high-efficiency, specularly-selective glazing carefully chosen for solar interactions with the building facade and other variables.
- Install interior or exterior shading devices.
- Install insulation in strategic locations.
- Undertake strategic air sealing, including duct work.
Plug Loads
- Use low-energy sleep functions on computers and printers.
- Choose ENERGY STAR office equipment and appliances.
Employee
- Ensure building maintenance and cleaning staff are enthusiastic about savings and adopt work habits that support energy efficiency.
- Provide training for key maintenance personnel in the proper operation of the building's energy management system.
- Involve all employees in energy savings efforts, provide efficiency education for work and home, and encourage employee suggestions on energy savings opportunities.
Funding for this Guide provided by:
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Recommendations for this and other sectors are available at www.coloradoefficiencyguide.com/recommendations.