light bulb 125wCan anyone out there help me out?

Doing some fact-checking for a book, I ran across a question I didn’t know the answer to: How much power is consumed by lighting in the U.S.? I spent a bit of time Googling for an answer, but at risk of looking like a dim bulb, I have to confess — I just couldn’t figure it out!

The Green Home Guide says that lighting uses 5 to 10 percent of household electricity. That lines up pretty closely with figures from the U.S. Energy Information Administration (part of the U.S. Department of Energy), which reports that, as of 2001, electric lighting represented almost 9 percent of total household power consumption.

But another branch of the Department of Energy says that lighting accounted for over 16 percent of electricity use in households (PDF), and 24 percent in offices and stores (PDF). Based on these figures, and after I add in industrial electricity consumption, it looks to me as if lighting represents about 17 percent of total electricity consumption in the country.

So that’s getting pretty close to the figure of 20 percent, which appeared in our 1999 book, Seven Wonders. But the text of that book also notes that electricity consumption from lighting would be even higher, if you include the extra air conditioning that’s required by all those hot bulbs in your house in summertime. And, in fact, this New York Times story from earlier in the year cites figures claiming that lighting consumes close to 22 percent of the nation’s electricity.

But that’s not the end of it: the Worldwatch Institute report says that lighting consumes 15 percent of household electricity, but up to 34 percent of the nation’s electricity overall!

Hmm. So light bulbs represent somewhere between 5 percent of home electricity consumption, and 34 percent of total, economy-wide consumption. That last figure is a real outlier, so I’m inclined to discount it. Still, it’s quite a spread, and all from reputable sources.

Which leaves me baffled and, er, in the dark. So if anyone else can shed some light on the subject, feel free to illuminate me.