Earth Hour math. Heh:

…The lights on the suspension cables of the western span of one of the busiest bridges in the world are just for decoration, not for navigation safety or whatever. Pretty. They sure make a big difference to the look of San Francisco at night when they are turned off.

Question: Turning off these decorative lights for an hour saves enough electricity to power Al Gore’s house for how many minutes?

Answer: About 13 minutes. Let’s work on that math, after the jump.

O.K., the “architectural necklace” uses 600 nine-watt bulbs, per the Oakland Tribune.

So, (600)(9)= 5.4 kilowatts. Over one hour that equals 5.4 kilowatt-hours of juice saved by Earth Hour when these 600 lights were off. Remember this number, we’ll use it later.

Al Gore’s house burns an average of 18,400 kilowatt-hours per month, per the rumour fighting Snopes.com.

So, (18,400)/(30 days per month)= 613 kilowatt-hours per day. And (613)/(24 hours in a day)= 25.5 kilowatt-hours per hour (which is basically saying the house has average burn of 25.5 kilowatts).

Taking the 5.4 kilowatts of the decorative bridge lights and dividing by the 25.5 kilowatts of the house and you get .212 hours. Which is hard to understand, but you get to minutes by multiplying by the 60 minutes in an hour and you get 12.7 minutes.

So, that’s much electricity was saved by turning off these lights in San Francisco - enough to power A.G.’s house for about 13 minutes.