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Reduce US air conditioning costs by 20%

The New York Times has a story about how energy secretary Steven Chu says the US can easily save as much as 20% of our national energy costs for air conditioning. The solution isn't rocket science - just make sure that buildings in the south have white roofs. Since dark roofs absorb more sunlight than white roofs, they can heat up a building much more efficiently - leading to higher energy costs for cooling that building. In the colder climes this may not always make sense because you end up having to pay more to heat the building in the winter, but in states like Texas this is a no-brainer. According to the story, houses with reflective tin roofs used to be common in Florida before air conditioning (and before the oil companies discovered they could make even more money in asphalt - which is used in roads of course, but also roof tiles). These asphalt shingles absorb as much as 90% of the sun's heat energy, while a white roof absorbs as little as 10%! [Nate begins to see a conspiracy] What I think I need at my latitude is roof shingles that are black at low incident angles (when the sun is low in the sky) and white (or at least more reflective) at high incident angles (when the sun rides high in the sky in the summer). Oh, and those shingles should all have integrated solar panels which lock together into a giant roof-net.