What’s the Deal with White Roofs

White Roofs, Fighting Climate Change!?

If you’ve ever gotten into a car with black leather or cloth seats on a very hot day, you’ve probably noticed that it’s much hotter in the car than outside. Moreso, cars with lighter interiors like tan or beige don’t usually get as hot as cars with dark interiors. It’s a fact of life we’ve all accepted but have you ever given any thought as to why this is the case? Also, how does this relate to “white roofs?”

First and foremost, to understand why dark interiors get hot and why white roofs are preferred, we need to dive into some science. The most important aspect in understanding why black cars get hot and why consumers prefer white roofs is this. Black surfaces absorb all visible wavelengths of light. When a black surface absorbs light, the light is turned into another form of energy, heat. So essentially, sunlight to surface, surface to heat. Compare that to a white surface which reflects all visible light. Instead of absorbing light and turning that light into heat, light is simply reflected off of a white surface. Because the light is reflected, there isn’t an opportunity for the light to be turned into another form of energy, in this case, heat.

Going back to the example of the hot car, on a hot sunny day, cars with black leather will absorb the sun’s rays creating an oven while cars with white interior reflect the sun’s rays resulting in minimal temperature change. Interestingly, the same phenomenon occurs on any dark or light surface, including roofs.

Over the past few decades, there’s been a trend among consumers and businesses to change up the roof over their heads. In many cases in past decades, St. Louis flat roofs would be covered with a black coating. This black coating prolonged the life of a roof and made buildings more energy efficient. However, now that the overall population has become more climate conscience, we’ve realized a major drawback of traditional roof coatings.

Dark roofs absorb light creating an insane amount of heat. That heat is trapped below the Earth’s atmosphere contributing to climate change. Additionally, the roofs aren’t energy efficient as they increase a building’s overall temperature. Enter the white roof. White roofs reflect the sun’s rays which mean heat isn’t being trapped under the Earth’s atmosphere. Furthermore, white roofs keep a building cooler and more energy efficient.

Using the science behind what makes a car with black leather hotter than a car with white interiors, roofers have managed to help fight climate change and cool buildings. Most consumers and businesses have begun installing white roofs to limit energy costs and to help fight climate change.