Black paint emits heat much more than white paint, and white paint reflects heat much more than black paint. Thermochromic paint changes colour depending on heat... So why not paint houses in a specialized mixture, so when it gets too hot, the south-facing sides of a house turn white, and the north-facing sides of a house turn black. And vice versa (and vice versa again, if you're in the southern hemisphere).
May not save *that* much on heating/cooling bills, but would be funky to look at.