I've known for quite a while that CFLs (Compact Fluorescent Bulbs) were cheaper in the long run, but I was ambivalent about the savings, and was under the impression that it wasn't that much of a difference anyways. Now that I'm trying to become more disciplined and save money wherever I can, I decided to do an honest evaluation of the potential savings.
We are likely moving in January, so I wanted the CFLs to pay themselves off before then since I don't know what kind of lighting our yet-to-be-found new house will have.
My plan was to a) analyze the costs and b) stick all the existing incandescent bulbs into a shoebox till we're moving out and take the CFLs with us.
We now have all CFLs, except for the two porch lights which are almost never used and which are difficult to replace anyways. If my estimates and calculations are correct, we should save about $10 a month and recoup our costs in four months.
Below is the spreadsheet I used for my calculations. Please let me know if you see any errors. The in-line view doesn't have quite the whole sheet. Please view it on Google docs or download it to see the full thing.
(Post continues after spreadsheet)
View it, Download it as ODS, Download it as XLS.
As you may have noticed, the longer you leave your lights on the sooner you recoup your costs. The obvious solution is of course to leave your lights on all day long. You'll be saving money before you know it! ;-)
There are some minor issues to switching to CFLs. If you're concerned about the color of your lighting, you may want to buy just a couple of bulbs and try them first. The CFLs, though they claim to be pure white, daylight or whatever do seem to have more of a blueish tinge than the incandescents.
I put the bulbs in our house last night, and due to the color of the glass around the light fixtures, the color temperature change isn't that noticeable, except in the bathroom, where we have a built-in vanity with six bare bulbs surrounding it.
When my two year old walked into the bathroom this morning, he said "We got new walls in the bathroom?", "No" replied my wife. "Somebody painted the walls in the bathroom?" returned my son. The color change isn't bad, but it does exist and may take some getting used to. For $10/month though, I'll do it.