Rhys Carpenter Library

An Analysis of Return on Investment (ROI) and Carbon Footprint Reduction

Rhys Carpenter Library

After counting 916 light bulbs in Rhys Carpenter Library last Thursday, we complied the data and ran some analysis on three major types of bulbs. The two most widely used bulbs in this building are T8 and U-Shaped T8. As for the art exhibition, Carpenter Library uses PAR 38 for dimmable illumination. All three types have existing LED replacements. The replacements for T8 and PAR 38 are LED 6114 and LED 1666 respectively, and Jim McGaffin helped us acquire some detailed information on these two models. We’ve found one manufacturer that produces LED replacement for U-shaped T8, and unfortunately, without price information listed on their website. Therefore we approximately the price as $100 each.

The ROI is composed of two parts — from energy savings and from labor cost savings of changing the bulbs as LED has an extended lifespan of approximately 50,000 hours.  The abbreviated formula for ROI is as follows:

ROI = Energy Savings/Year + Labor Cost Savings/Year – Cost (Material, Labor)

For complete ROI formula, breakdown of each section, and details on Carbon emission reduction calculations, please click here.

The result from Carbon emission reduction is quite encouraging. With the high market price for LED technology, however, the ROI alone does not appear to be very promising.  It could turn out better if we take into account the incentives received from PECO’s Smart Ideas Program.

If we replace all T8, U-Shaped T8 and PAR 38 in Carpenter, then about 7835.26 lbs of CO2 will be reduced each year, which is equivalent to 3.9 tons.

Follow this link for Carbon emission reduction calculations.