[Kendall] Lighting Retrofit
Mount Holyoke College undertook the retrofit of gymnasium lighting in Summer 2005. The basketball gym was a prime candidate for retrofit because of its advanced age, heavy usage patterns, large number of fixtures, and availability of new technology.
What We Had
Existing lighting was mercury vapor HID [high intensity discharge]. HID lighting uses a ballast to regulate the power applied to a sealed arc tube, where compounds are vaporized to provide an intense light source. HID lamps can take up to 5 minutes to start when cold, and up to 15 minutes to restart when switched off. While these lamps are much more efficient and last much longer than incandescent, newer technologies have better efficiency and color rendering.
Total power: 16,560 watts
Controls: switches usually left on because of restrike time
Brightness: 19.9 foot-candles
What We Changed To
High-output T5 fluorescent lamps have excellent color rendition and lumen maintenance, and the highest lamp efficacy, measured in lumens per watt, of all the fixtures we considered. Light quality is further improved because of its diffuse nature, which reduces shadowing. Fluorescent lamps have the additional advantage of a near-instant start, simplifying the use of occupancy sensors and ambient light controls to reduce burn time.
Total power: 8460 watts [reduced 50%]
Controls: sensors automatically turn off lights when gym is empty
Brightness: 46.7 foot-candles [increased 135%]
—— 46,456 KwH and $4,000
Annual Emissins Reduction:
—— 140 lb. NOx [smog] and 400 lb. SOx [acid rain]
Annual Greenhouse Gas Reduction:
—— 24 TONS OF CARBON DIOXIDE [That's equivalent to removing 5 cars from the road or planting 3 acres of trees]