Asha Stenquist, Surita Patel, Freena Chohan
Possible Energy Saving Light Changes
1) Switching to energy saving lights: compact fluorescent (CFL) light bulbs use up to 75% less energy
and last up to 10 years longer than incandescent bulbs1
2) Turning lights off when not in use: occupancy-sensing light switches automatically turn lights off
when room is not in use; daylight-sensing light switches turn lights off when ambient lighting is sufficient;
timers turn lights off at same time each day
Potential Benefits of Energy Saving Lighting
1) Reduced energy use
2) Reduced energy costs
3) Reduced environmental footprint (particularly reduced CO2 emissions)
4) Enhanced image as an environmentally aware institution
Potential Projects
3rd and 4th Floors of Pendleton Hall
1) Atrium: daylight override and timer
costs: $140 savings: $517.19 per year payback time: 3 or 4 months
2) Hallways: Change 48 incandescent lights to CFLs
costs: $52 savings: $206.49 per year payback time: 4 or 5 months
3) Classrooms:
a. install occupancy sensors
costs: $280 savings $85.84 per year payback time: 3 years
b. turn off ½ of lights
costs: $0.00 savings: $110.38 per year payback time: instant!
4) Small Rooms: install occupancy sensors
costs: $350 savings: $117.42 per year payback time: 3 years
5) Bathrooms: install occupancy sensors
costs: $350 savings: $137.59 per year payback time: 3 years
6) Offices: no potential changes
payback time for occupancy sensors is too long
1 www.gelighting.com
2Audit of Wellesley College’s Greenhouse Gas Emissions
Campus-Wide Implementation of Pendleton Projects
Pendleton is already lit relatively efficiently; this is not true for all buildings on campus. The
potential projects outlined for Pendleton can be applied campus-wide, with even greater results. For
instance, installing occupancy sensors in just one set of stacks in Clapp Library would cost $450
initially, and would save $3195.65 per year
Calculation Process
- Number and types of lights were determined through direct observation and from Wellesley
College lighting plans
- Average number of hours lit was estimated by direct observation at various times of day
- Price of energy was assumed to be $0.08
- CO2 emissions per KWH was assumed to be 2.0438 x 10-3 of CO2 2
At a Glance…
Description: Evaluation of replacing inefficient
incandescent lights with compact fluorescents, and
installing occupancy or daylight override sensors to
reduce energy use, energy cost, and environmental
footprint
Buildings: Pendleton is already relatively
environmentally efficient, so changes would be simple
and minimal; other buildings on campus are less
efficient, so the same changes that are possible in
Pendleton would result in greater savings elsewhere.
$ Costs and Savings in Pendleton:
If Projects with payback time less than 3 years were
implemented…
Total costs= $1,172
Net savings in first year= $2.91
Net savings in following years = $1,174.91
Environmental Impact:
Reduction in CO2 emissions=
30 tons per year
(equivalent to the CO2 absorbed annually by 4,615
healthy trees!)
