Lilek’s talks about Light Bulb Wars.
When I owned a house in Seattle I replaced all my bulbs with fluorescents. Difference in my energy bill? Nil. Average life of bulb? 18 months (despite 7-year guarantee, wish I’d kept the receipts). Apparently, one is supposed to leave a fluorescent bulb on for a minimum of 15 minutes or the lifetime is shortened. I don’t remember what I paid for the fluorescents, but I’m sure it cost me more to use them than incandescent bulbs. I tend to use lower wattage incandescent bulbs, 15 or 40 rather than the 60 or higher.
Speaking of energy saving measures (or the lack thereof) I also spent $8,000 replacing the aluminum frame, single pane windows with vinyl double pane windows. Impact on heating bill? 5% or $30 a year. Admittedly, in Seattle I didn’t have an air conditioner (not really needed there) and the average winter low is in the 30s. The savings might be more dramatic in less temperate climates. Part of the lack of improvement in efficiency is likely due to more insulation was needed in the attic. Still, from an energy savings perspective, it isn’t likely the windows will “pay for themselves”. I don’t consider the windows a waste of money, however. They added to the value of the house, and I suspect had some influence on the sale of the house. They’re significantly more attractive than aluminum framed windows.
The improvement that made the biggest impact was a programmable thermostat ($100). Dropping the temperature during hours of sleep and work led to a 40% decrease in the heating bill. That figured out to about $80 a winter. The fact that it had a cool hidden panel with lots of light up buttons and a digital readout was just gravy.