Technologies > 15 TIPS FOR BEATING STANDARD 90.1
Introduction: Lighting accounts for 25 to 40 percent of a building’s total energy consumption, and up to one-half of the monthly electric bill. For the past two decades, the lighting industry has recognized energy efficiency as a major market driver and responded with a wide variety of energy-saving lamps, ballasts, fixtures and controls. A number of these approaches can be used to exceed the lighting power density requirements of ASHRAE/IES 90.1-2001.
To help, ASHRAE recently published the Advanced Energy Design Guide for Small Office Buildings (available at www.ashrae.org), which demonstrates how to design new office buildings that are at least 30 percent more efficient than allowed by Standard 90.1-1999 (which has the same LPD values as Standard 90.1-2001, upon which the Commercial Buildings Deduction is based).
Developed in conjunction with other organizations, including the American Institute of Architects (AIA), the Guide focuses on office buildings <20,000 sq.ft., which represents the bulk of office space in the United States. It provides energy-saving recommendations across the entire building, including lighting, for each climate zone in the U.S.
Tips: Below are 15 tips for beating the 1999 (2001) Standard and preserving or improving lighting quality in commercial applications, derived from the Guide, advice from manufacturers and other sources. These tips do not address daylighting or exterior lighting, only interior electric illumination:
- Increase luminous comfort by distributing light on walls and ceilings.
- Specify a Color Rendering Index (CRI) rating of >80 when color rendering is an important issue in the application, along with “white” light sources between 3000K and 4100K in color temperature.
- Consider lower and/or translucent partitions in open plan offices.
- Choose an 80+ percent reflectance for ceiling finishes and a 70+ percent reflectance for walls and vertical partitions. For indirect lighting and daylighting, a 90 percent ceiling reflectance is preferred.
- Utilize lighting systems (lamp-ballast combinations) that provide a minimum maintained efficacy of 90 lumens per watt.
- Specify occupancy sensors wherever practical to ensure that unused lighting is shut off.
- Consider high-efficiency fluorescent electronic ballasts.
- Consider high-lumen “Super T8” lamps in combination with low-output ballasts to reduce power or with standard or high-output ballasts and then delamp and/or reduce fixture count.
- Consider low-wattage ceramic metal halide lamps as an alternative to tungsten halogen lamps, and pulse-start metal halide instead of probe-start metal halide.
- In some indirect lighting applications, it may be possible to use one T5HO lamp in place of two T8 lamps or otherwise increase the fixture spacing, reducing the number of fixtures and/or lamps used.
- Use only electronic ballasts for linear fluorescent, compact fluorescent and metal halide lamps.
- Use incandescent lamps as little as possible. Consider compact fluorescent or low-wattage metal halide instead when feasible.
- Layer the lighting design where practical so that the general lighting system does not do the heavy lifting of task lighting.
- Choose lamps with maximum service life to minimize maintenance.
- Choose light fixtures that offer the highest optical efficiency. Fixture design is an often overlooked but powerful strategy for achieving energy efficiency. Select fixtures that get the light where it’s needed at the great possible efficiency.
T8 and T5 linear fluorescents, compact fluorescents, pulse-start metal halide and efficient fixture optics should form the nucleus of a high-efficiency lighting design. However, this does not prohibit the use of less efficient sources on a limited basis.
