Cool roofs explained

A cool roof reflects sunlight and gives off heat efficiently, so less of the sun's heat goes into the house. A standard roof can reach 150°F or more in the summer sun. A cool roof can bring that down by as much as 50°F, so the house needs less air conditioning.

A cool roof is one of several ways a house can be designed to stay cool. Overhangs, awnings and reflective coatings on windows and outside walls do the same kind of work, keeping the sun's heat out before it reaches the rooms below.

What makes a roof cool

A cool roof can be a highly reflective paint, a sheet covering, or highly reflective tiles or shingles. It doesn't have to be white. Many cool roof products use darker pigments that reflect strongly in the near-infrared part of sunlight, which the eye can't see. A white roof will usually still be cooler than a dark one, because it reflects both visible and near-infrared light.

New and existing houses

A cool roof can be part of a new house or added to an existing roof. Like any change to the design of a house, it also affects comfort, durability, health and safety, so weigh it along with the rest of the house. Design features such as landscaping, windows and cool roofs can all save energy and money. ENERGY STAR certifies cool roof products, and the Cool Roof Rating Council publishes information on them. Almost any house can benefit, but the climate and other factors decide how much. Have a roofing professional do the work.

An annotated example

What to do next

Note what your roof is made of and its color in your home records. Which energy upgrades to do first covers where the roof fits among other upgrades.