It’s the middle of summer here in Auckland, and I am baking. Not because it is unbelievably hot (currently a pleasant 24°C outside), but because a) my little wooden house has virtually no ceiling insulation, and b) at some point some total dipshit decided it would be a great idea to paint my tin roof black.

So I have this situation that while the sun is shining, the temperature inside rapidly climbs beyond the ambient temperature outside. The only time of year where this makes any sense at all is on sunny winter mornings, and even this won’t begin to compensate for the fact that a black-roofed house with no insulation will radiate ALL of its heat away during the night, making winter nights and mornings unbelievably cold.

Builders here just don’t seem to get thermodynamics.

Lots of other houses with tin roofs have theirs painted red, I guess to make them fit in with tiled roofs better, and red is only going to be slightly better than black. The best color for a metal roof is silver, because just as silver tends to reflect a lot of energy outwards, it also reflects it inwards. That’s why “space blankets” are silver… it’s not because they want to look more sci-fi, it’s because the shiny foil provides much of the insulating property of the blanket.

Hopefully in the near future governments will include the cost of non-reflective surfaces in estimates for global warming and maybe strike all the stupid neighborhood laws that might require people to paint their perfectly good silver roofs for some aesthetic reason. If anything we should have goddamn mirrors coating our houses… that would provide some truly excellent insulation and reflect a large amount of shorter wavelength solar energy back into space before it can be absorbed, re-emitted and trapped as atmospheric heat.

See also: New anti-warming tool: white roofs