About 8 months ago, we changed out 15 of our high use light bulbs to compact florescent bulbs. They included our outdoor lights, which are on every night when it's dark, and several high use bulbs within the house in our family room and entry way. We've noticed that since we made this change, our electric use has dropped by about 15% compared to the same month in the previous year when we had the older style lights. We were surprised to see what a difference it made.

Remember that, while they save energy, compact fluorescent lamps contain mercury and need to be disposed of properly. As with everything, there are trade-offs.

You can figure out how much any watt bulb costs to run per month. Say your old bulb was a 60 watt bulb and the compact florescent replacement draws only 15 watts (typical). Say the light is on four hours a day. In a 30-day month, that's 120 hours.

Now if your electricity, like mine, costs about $0.07 per kw hour, then the bulb at 60 watts (or 0.06 kwatts) costs 120 hours * 0.07 dollars/kwhour * 0.06 kwhours = 50.4 cents per month.

The 15 watt compact florescent uses only 1/4 of that power, so it would drop from 50.4 cents to about 12.6 cents a month. So you'd save about 37.8 cents a month per bulb...let's say 40 cents a month, per bulb. If you have 15 bulbs running like that, at 4 hours/day, you'd save $6/month on your electric bill with these bulbs.

Andrew

We've switched to flourescent here some time ago. A few downsides -- can't be used with dimmer switches and not really good for short-lighting uses such as closets and halls . . . they don't brighten up fully before one switches it off -- probably not a big deal, but waiting to see things clearly in a dark closet can get annoying -- but everywhere else in the house ought to be using these things.

Outside we're using 35w Sodium lights (damned bright!) although I have a 150w sodium lamp which can be used to rebuild engines at night and contacting aliens on other planets.