What Color Roof Keeps Your Home Coolest?

There are some great things about living in Southern California, and most Angelenos would mention the climate. However, midsummer can see the inside of your home turn from comfortable to sweltering.

With the mercury climbing and your AC working overtime to keep you cool, your energy bills are growing expensive. As an experienced Los Angeles roofer, we can tell you that the color of your roof matters to keep your home cool.

Albedo Matters

White roofs keep your home coolest. But why?

Visible light is the portion of the electromagnetic spectrum we can see; sunlight contains visible light, near-infrared, and ultraviolet (UV) radiation. Different surfaces reflect different amounts of light, a property known as albedo.

Albedo: The Technical Part

A surface that reflects all the wavelengths of visible light appears white, while one that absorbs all the visible colors looks black. Colors such as red, green, and blue result from a specific wavelength reflecting (the shortest wavelengths are violet, and the longest are red).

Visible light isn’t warm, but when absorbed by a surface, it loses some energy and becomes infrared radiation, also known as heat. A black surface absorbs virtually all the light that falls on it and turns it into heat, warming the object a lot.

What This Means for Your Roof

A white surface reflects most of the light that hits it, meaning that very little is absorbed to become heat. Cool roofs in Los Angeles are probably white and reflect anywhere from 60% to 90% of incoming sunlight, with very light-colored roofs (pale gray or sand) close behind.

The potential temperature difference between conventional and cool roofs in Los Angeles is significant. Whereas most roofs will hit 150°F or more on a sunny summer afternoon, a cool roof will max out around 100°F.

Is Visible Color the Whole Story?

Having explained all that about white reflecting the most light and staying the coolest, we must tell you that’s not the whole story. Around half of the sunlight that reaches the surface of our planet is already near-infrared (invisible heat energy).

There are certain pigments (chemicals that create color by reflecting visible light) that reflect this invisible near-infrared radiation. The result is a dark-colored surface reflecting a lot of incoming sunlight (between 30% and 60%) and staying cooler than you would expect.

The upshot is you can have cool roofs in Los Angeles and have them be dark in color. Sure, they won’t be as cool as white, but these so-called “cool-colored” roofs still offer many of the benefits.

Many roofing products come in cool-colored options or can be treated. Speak to your Los Angeles roofer to find out more.

Cool Roofs in Los Angeles: The Lowdown

Cool roofs reduce the need for AC units and thus reduce your energy bills; they may also qualify for rebates from government programs or utility companies.

The lower temperatures are particularly beneficial for indoor spaces that aren’t air-conditioned and could otherwise become dangerously hot. Decreased roof temperatures help prevent the degradation of roofing materials, potentially extending roof service life.

Speak to a Los Angeles roofer about cool roof options, from new shingles to a coating.