... Green Real Estate Analysis ...

Power Savings Is Green

The US Dept of Energy's CO2 report here says that in 1999 the US produced 2245 million metric tons of CO2 in generating electricity, and in the same year generated 3691 billion kilowatt-hours of electricity with a national average output rate of 1.341 pounds of CO2 per kilowatt-hour.
Feature Tradeoffs Average Cost Average return per year Equivalent tons of carbon saved per year Equivalent mortgage payment
CFL: Compact Fluorescent Light Bulbs Benefits
  • Just "buy a CFL and save $30 in electricity over the life of the bulb", says the US Energy Star website.
  • Uses 3 or 4 times less electricity as compared with incandescent. A 60 watt incandescent will typically produce the same amount of light as a 15 watt CFL.
  • Light costs 20% of your home electricity bill.
  • My house has 58 lights I can turn on, not even at Christmas.
  • Illegal to throw away in most states
  • Difficult to return for recycling (except at Ikea in Renton)
  • Possible toxic mercury outgassing if broken, requiring Hazmat cleanup, details here. Although a bulb contains only 5mg of mercury, as compared with 500mg in an older thermometer, atomized or aerosolized mercury is much more dangerous (since you can breathe it) than liquid mercury. If you break one, keep everyone out of the room for at least 15 minutes.
  • Not for bathrooms as humidity can shorten the life of a CFL.
  • Not for three-way or dimmer switches unless specially rated.
  • Not for recessed (can) lighting fixtures, use a reflector style CFL.
  • Not for quick lighting (lights used with frequent on/off or short-on cycles).
The bulbs are pretty competitively cheap themselves.
The main effect is that your power bill goes down.
(58 bulbs in my house) * (US$30 per bulb, which at 6000 hours should last 6 years) / (6 years) = $290 per year

Realistically, I can reduce the wattage of about 20 bulbs for about 90 minutes per day from 60 to 15 watts each:

20 bulbs * (1.5 hrs per day per bulb) * (-45 watts) * 365 days/yr
= -492.75 kilowatt-hours per year

which saves

660 pounds of CO2 per year.

$290/year * 1 year / 12 months



Copyright © 2000-2007, Thomas C. Veatch. All rights reserved.
Modified: June 9, 2007