Energy Use & Efficiency
Lighting the campus uses significant amounts of electricity. Changes in lighting types and patterns to conserve electricity throughout the campus fall into three major project areas: gymnasium retrofitting, John M. Green Hall and other exit lighting; and scheduled replacement of incandescent lamps in residences and offices throughout campus.
Gymnasium Energy Retrofit Project
The project is budgeted at $100,000 and will save up to $50,000 a year. The electricity savings will also reduce emissions from power plants supplying our local grid. We estimate that this project will eliminate the release of 3.5 tons of compounds that cause smog and acid rain, and 350 tons of carbon dioxide, each year. That greenhouse gas savings is equivalent to planting 70 acres of forest or taking 80 cars off the road.
Existing lighting was metal halide 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 five minutes to start when cold and up to 15 minutes to restart when switched off. While these lamps are much more efficient and last 10 times longer than incandescent, newer technologies have even better efficiency and quality of light.
Pulse-start metal halide lamps generate the same light output while drawing less current. They also have the advantage of shorter start and re-strike times. Because they were developed primarily for the retail marketplace, they have improved color rendering and maintain a more constant light output over time (lumen maintenance).
T5 fluorescent lamps, developed in 1995, and T5HO lamps are suitable for gym lighting. These lamps have excellent color rendition and lumen maintenance and the highest lamp efficacy (measured in lumens per watt) of all the fixtures we considered; they also reduce shadowing. Fluorescent lamps have the additional advantage of a near-instant start, simplifying the use usage-based controls to minimize burn time.
Because the T5HO fluorescent lamps have the highest efficacy, we selected them for Ainsworth and Scott gyms and the Climbing Wall. We are also retrofitting each area with occupancy sensors that automatically extinguish the lights when the rooms are empty. Ainsworth will also have bi-level controls, with the brightest level reserved for competition play. Each of the spaces will actually be brighter after retrofit, even though the wattage will be reduced 67 percent.
Two options are under consideration for the Indoor Track and Tennis (ITT) Facility, the college's largest single "room" space. The existing ITT lights draw the electricity equivalent to a 125-hp motor, a very substantial load.
- The first option leaves the existing fixtures in place, facing upward, to provide 100 percent indirect, reflected light. Retrofitting the existing 1000-watt lamps and ballasts with 750-watt pulse-start metal halide will decrease the power by 25 percent. Each fixture will have an occupancy sensor and bi-level controls that drop the light to half power when the space below is empty. When motion is detected, the switch to full power and brightness is instantaneous.
- The second option is to replace the fixtures with new T5HO fixtures that provide nearly 100 percent direct light. The savings are substantially greater because wattage is reduced by 67 percent. While the light quality (color, shadowing) and lumen maintenance are better, there is concern about the glare with direct lighting. Because glare is such an important consideration when playing tennis, maintaining the indirect light may be the best option.
To make a better evaluation, both options will be considered fully, and samples may be installed before a decision is made.
John M. Green Hall Exit Signs Project
In July 2005, the built-in exit signs at John M. Greene hall were replaced. This was not a straightforward retrofit, since these signs were built into the existing millwork in an architecturally-sensitive location. The existing units used two 15-watt incandescent bulbs each and a tremendous amount of energy, generated excess heat, and burned out often. Custom LED kits were ordered that fit the existing signs. These use just 2 watts each and last over 25 years. Annual savings are projected to be 6,200 kWh, $1,000, and 4,200 pounds of CO2.
The campus has a significant number of exit signs throughout its buildings, and these are also being changed to LED sources.
Incandescent Light Replacement Project
At Cutter-Ziskind residence, we will replace 240 incandescent 75-watt flood lamps with 16-watt compact fluorescents, and 38 incandescent exit signs with LED's. This will decrease the lighting load by 72 percent (13,700 watts) while saving 88,600 kWh and $7,300 a year.
In addition to energy savings, we will save on maintenance as well. Compact fluorescent bulbs are rated at 8,000-12,000 hours, and we have had several go beyond 14,000 hours. In contrast, incandescent bulbs are rated for 1,000 hours. Although the maintenance savings may not be as visible in dollars, there are many other tasks our housekeeping staff can do when they're not changing light bulbs that burn out six to eight times a year.
The change will also reduce the amount of pollutants released by the power plants that generate our electricity. The annual emissions reductions are 300 pounds of compounds that cause smog and acid rain, and 30 tons of carbon dioxide which is a greenhouse gas. That savings is equivalent to planting six acres of forest land or taking seven cars off the road for good.
There are approximately 3,000 potential incandescent retrofits on campus, not counting the desk and table lamps that students bring for their rooms or staff add to their overhead lighting.