Monday, January 08, 2007

On the Wonders of Compact Fluorescent Bulbs

Three of the bulbs pictured on the left draw 40 watts of electricity. One of them draws only 9 watts. Can you guess which one?

I've been a big fan of compact fluorescent (CF) bulbs for a couple of years now, but I was shocked to hear recently that only 6% of households in the US are using them. CF bulbs don't work for every application, but as I just discovered, even "aesthetic" bulbs can be replaced with CFs. And certainly most of your everyday bulbs can. A 100 W incandescent bulb, for example, can be replaced with a 23 W CF that produces the same amount of light. To my eye, at least, they appear completely identical. Not like those ugly whitish fluorescent things they tried to sell us 20 years ago, which for obvious reasons never caught on.

The economics on this are rather startling. If you replace 10 incandescent bulbs of 100 W each with comparable CF bulbs, that saves you 770 W for every hour they're on. If they're on for an average of 4 hours a day, that's just over 3 kilowatt-hours (kWh) saved per day. At about $0.10 per kWh of electricity, that'll save you around 30 cents a day. It may not sound like much, but over a year those savings add up to over $112. Just for changing light bulbs.

The CF bulbs are certainly more expensive. If you buy them individually, they cost about $5 each, though you can get them cheaper in bulk. But they're also guaranteed to last for 5 years, unlike incandescents which last only a matter of months, so it equals out in the end. (One hint though: save your receipts and UPC; you may buy a whole package that ends up going sour, which happened to me once.) But you don't have to wait for the bulbs to live out their full life-span in order to get your money back. Switching 10 bulbs will cost you at most $50, and assuming you use them regularly, you will have doubled your money in less than a year.

Another way to think about this is to assume that you're making an investment. $50 invested today will, within 5 years, return $560 in energy savings. Subtracting your original investment and assuming the interest is compounded annually, that's about a 60% annual return on your money over the life of the bulbs. I challenge anyone to find me an investment that guarantees a better than 60% return. I mean seriously, if you know of one please tell me.

Absent finding that magical guaranteed 60+% return, switching to CF bulbs is about the best investment that anyone can make. To be sure, CF bulbs aren't entirely without their drawbacks. The biggest is that they don't get up to full brightness for about 15 seconds after you turn them on. But that is at most a minor nuisance. Another drawback that most of the CF bulbs produced are ugly and you don't want to use them in situations where you have a naked bulb jutting out from a light fixture. But as in the case above with my bathroom lights, even this is no long an issue in most cases. Barring these trivialities, there is no reason why everyone shouldn't be switching to CF bulbs.

In addition to saving you some serious duckets, switching to CF bulbs is good for the environment. Were everyone to do so, using the above assumptions and given about 100 million households in the US, that would save over 112 million megawatt-hours (MWh) of electricity per year. That's a lot. Unfortunately, the US generates over 4 billion MWh of electricity per year, so we're talking about only a small dent here. But it's a dent nonetheless. And you get paid for it.