Rule of Thumb #4 - Ignore Advice

01_blue_bulbs_pileYou've heard the advice about compact-fluorescent (CFL) bulbs: replace your frequently used lights with these, and you'll save money, energy and reduce global warming pollutants.

Well, I'm going to tell you to stop taking this advice. Instead, replace all your lights with CFLs.

In the old days when they cost $15, the original advice was fine. Now that you can purchase them for as little as $2 or $3 apiece, that advice no longer holds. It now makes more sense to replace them all.

“But they woe-on’t last as lo-onng,” you’ll hear people whine. Let’s do the numbers.

Assume that you have a 60-watt light that you switch on five times a day for two minutes each time (ten minutes total per day). You replace it with a 15-watt CFL that costs $3. Because of frequent switching, let’s assume its lifetime is hugely reduced by 75% to 2000 hours instead of 8000.

Your annual return on investment for that bulb is 5%-15% depending on your electricity rates and, dang, it will only last you for 33 years before you have to replace it. It might not be the 50% return you’ll get from some of your other fixtures, but it’s still a no-brainer. For a couple hundred dollars you can probably change out your whole house (a little more if you buy more expensive dimmables and 3-ways; visit for a good selection of bulbs). What are you waiting for? The climate to change?

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