In a cold climate like Minnesota's, is it better to have a light or dark house exterior and roof? We spend more of the year heating than cooling, so that makes me think dark. On the other hand, we live in a city heat island, and I would think dark colors would just add to that.
--Cynthia in Minneapolis, Minnesota
Going with lighter colors is generally best for many regions, but darker colors might be the best choice for the great northern city of Minneapolis. So you’ve got Mr. Green in the (rather rare) position of lacking a definitive answer. This is because of a gazillion variables: the insulation quality, the type of heating and cooling systems, the size and shape of the building, the pitch of the roof, and so on. (Even the absence of shade trees or wind-busting evergreens might come into play.) Obviously, every building in this country needs a thorough energy audit.
But you can get an estimate for your dwelling by using calculators provided by the EPA and the U.S. Department of Energy here and here. Plug in the math -- and do disregard idiots at town-hall meetings and right-wing bloggers who’ll no doubt claim that these sites are a scheme from Obama’s emerging socialist tyranny to invade your privacy.
Regarding heat islands, if you were to move to a hotter place like Los Angeles, the case for lighter colors is easy to make. For example, one study showed that if L.A. installed reflective roofs, reflective asphalt, and 10 million more shade trees, it could knock 5 degrees off its summertime temperatures and slash the need for air-conditioning by 18 percent. That’s a whopping amount of energy, with the added bonus of reducing the lung-searing ozone caused by higher temperatures.
Homes aren’t the only places where huge savings could occur; commercial buildings could reduce their energy use by 13 to 16 percent by taking energy-saving measures, which would not only hugely cut greenhouse gases, but save $30 billion per year on energy costs by 2030.