Daily Archives: March 8, 2008

A Very Gravia Situation

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While poking around looking into the DST-doesn’t-save-energy story, looking for something that didn’t just link back to the WSJ story, I ran across this: a new lamp being hyped by some sites with a “green” tint, called Gravia. (a second story is here at treehugger)

The lamp took second place in the Greener Gadgets Design Competition. It’s described as being gravity-powered, which is wrong. It’s human-powered — you lift 50 lbs, and the weight falling back down supplies energy to some LEDs, and is supposed to supply 600-800 lumens, or the equivalent of about a 40-W light bulb, for four hours. Something about this immediately struck me as being wrong. You aren’t going to power the equivalent of a 40-W light bulb with that, not even with really efficient LEDs. 50 lbs, lifted a bit over a meter, will require 250 Joules of work. Over 4 hours, that’s 17 milliWatts of output. That didn’t add up — even the best LEDs are only 5 to 10 times more efficient than incandescent bulbs. There’s no way this can work.

And sure enough, that’s what I found

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Forward, Sproing!

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Spring forward tomorrow (or tonight just before bed). Daylight Saving Time begins in the US.

Three things:

– It’s saving, not savings.

– “Don’t blame me, blame the dee-oh-tee.” DST is the purview of the Department of Transportation. Universal time is unchanged — from a timekeeping standpoint this is a non-event. Displays get changed for devices that read out in local time, but atomic clocks that have displays read out in UTC.

– It apparently doesn’t save energy, at least in Indiana. But the story (not surprisingly) gets it wrong.

For decades, conventional wisdom has held that daylight-saving time, which begins March 9, reduces energy use. But a unique situation in Indiana provides evidence challenging that view: Springing forward may actually waste energy.

But later,

They conclude that the reduced cost of lighting in afternoons during daylight-saving time is more than offset by the higher air-conditioning costs on hot afternoons and increased heating costs on cool mornings.

So the decades-old “conventional wisdom” is only wrong if there has been widespread use of air conditioning during that time. If, however, the use of air conditioning has increased in that time, the conclusion is wrong. What you can conclude is that that right now, in Indiana, DST uses extra energy. Because they are selfish bastards who like air conditioners way too much.