Numlock Sunday: Ames Alexander on the dark roof lobby

Photo by Jack Price-Burns on Unsplash

By Walt Hickey

Welcome to the Numlock Sunday edition.

This week, I spoke to Ames Alexander who wrote This little-known ‘dark roof’ lobby may be making your city hotter for Floodlignt. Here's what I wrote about it:

Roofs are about a fourth of the surface area of major cities, and the very basic principle of “dark absorbs more energy from sunlight than light roofs” dictates that if we were to make many dark colored roofs into, say, white roofs, we could save lots of energy in the summer on cooling costs, all for pretty much the same roof cost. This is indeed the case: light-colored roofs can be 50 degrees cooler on hot days than dark roofs, and Lawrence Livermore National Laboratory found that a cool roof on a house in central California cuts energy costs by 20 percent — and so at least eight states and over a dozen cities in other states have made requirements to install cool roofs, and the appeal of retrofitting roofs is high just because of the ene…