roof cooling basics

Roofs are responsible for up to 50% of home's cooling loads. And that means large air-conditioning bills. If your home overheats in summer and hot weather, reflective roofs and insulation are excellent means to solve the problem.

Common Dark shingles are energy-Inefficient

Common dark-color asphalt and fiberglass shingles absorb most of the solar radiation, and are a major cause of high-conditioning costs. A large amount of the unwanted heat in buildings comes in through the roof and attic. To solve this problem the most effective and direct answer is a reflective roof (also technically called cool roof).

Cool roofs

Use reflective roof materials for a cooler home in hot weather conditions. In some cases you just have to install these materials directly over the surface of your room, using an appropriate coating or membrane. These materials will decrease the heat transferred into attics and rooms by several degrees and will provide lower cooling costs. See: Roof coatings.

If your are re-roofing or building a new home, avoid common asphalt and fiberglass shingles and choose some metal, ceramic and other reflective materials. See: Metal, Ceramic and Roof Reflective Materials.

Roof insulation

Roof insulation is also a crucial element to achieve a cooler roof. Reflective roof materials and insulation complete themselves in most climates.

When installing a reflective roof, to attain maximum energy savings, consider also attic and ceiling insulation. Insulation isn't only crucial to get lower heating bills. It's also important to reduce air-conditioning needs.

See, for details:

Attic insulation
Roof and ceiling insulation
Reflective insulation

Cold climates and reflective roofs

The advantages of reflective roofs techniques and materials in cold climates is a controversial subject. But most experts agree that even in colder climates a cold roof is more advantageous than traditional low reflective and dark-colored roof materials.

See: Roofing and climate

Urban heat Islands

A «cool roof» doesn't mean only lower cooling needs. It will also increase the roof’s life cycle and reduce urban heat islands (higher urban temperatures relatively to surrounding countryside, due to dark and inefficient urban roofs and pavements), which is good for the environment.

The color of the roof

Most roofs in America and worldwide are dark-colored, absorbing up to 90% of sunlight and causing higher cooling needs and air conditioning costs.

If you are considering a new roof or a roof remodeling bet on a light color. Roofs with white and lighted colors are much more energy-efficient, namely in hot and mild climates.

See: Roofing and climate

Reflective roofs and attic fans

Attic fans are a good and cheap contribution to a cooler attic and to some energy savings in air conditioning bills. They don't solve overheating situations, and have a much more limited scope than reflective roof materials, but they can minimize some heating loads.

See:

Attic fans basics
Solar attic fans
Solar vs. electric attic fans

Radiant barriers and roof cooling

To reduce attic temperatures you may also install a radiant barrier (basically a sheet of aluminum foil) on the underside of the roof. A correctly installed radiant barrier can reduce heat gains through ceiling by a quarter.

See, for more information on radiant barriers: Reflective insulation

green roofs

A green roof is a roof covered with vegetation planted over a waterproofing layer. Green roofs are experiencing some popularity in some cities and states, and are an ecological answer to roof overheating.

See, for details: Installing a green roof and Green roofs costs, pros and cons