Among the many worries of a building owner or manager, staying cool in the summer and cutting costs are two things which always present themselves. Unfortunately, they seem to be in complete contradiction of each other. The sun beating down on your roof can cause its temperature to rise. According to the Department of Energy, on a sunny day the temperature of a traditional black roof can be 50°F warmer than the air temperature. When dealing with this warm climate, it would be beneficial to know how to cool your roof in the summer. However, with the growing popularity and availability of “cool roofs,” this might not be the case anymore.
What are Cool Roofs?
Cool roofs have been designed to reflect more light and absorb less heat than traditional roofs. They have a high emissivity, which means that they emit infrared energy. They can be made of a sheet covering, highly reflective paint, or highly reflective tiles or shingles.
Benefits of Cool Roofs
There are many benefits to installing a cool roof on your home or building.
- Lowers utility use and cost. A cool roof reduces temperatures internally and externally so homeowners will have to rely less on their air conditioning system. Homeowners can spend less on their energy bills without sacrificing comfort.
- Provides a longer life span and fewer maintenance costs. High temperatures cause shingles to expand and contract, causing cracks in their surface. A cool roof can help prevent this damage, extending the roof’s life.
- Reduces the heat island effect. When there are many buildings in a small urban or suburban area, air temperature can feel higher than it is. If buildings in tight areas replace their roofs with cool roofs, then it can reduce the air temperature around them. Also in these areas, these roofs can lower peak electricity demand which will help prevent power outages.
- Reduces air pollution. Cool roofs reduce cooling energy use in buildings, which reduces power plant emissions such as carbon dioxide and mercury.
Costs of Cool Roofing
Costs will differ depending on many variables like location, local laws, and climate. However, the Environmental Protection Agency estimates the increased cost for cool roofs is between 0 and 10 cents per square foot. This slight increase is offset by the savings. According to epa.gov:
A California study found that cool roofs provide an average yearly net savings of almost 50 cents per square foot. This number includes the price premium for cool roofing products and increased heating costs in the winter as well as summertime energy savings, savings from downsizing cooling equipment, and reduced labor and material costs over time due to the longer life of cool roofs compared with conventional roofs.
Initially installing the cool roof products may be more expensive than traditional roofing materials. The savings will come from reducing air conditioning expenses and a longer lasting roof. This is an investment where you benefit over time through lower energy costs.
Types of Cool Roofs
Cool roof coatings are white or use reflective pigments that reflect the sunlight, rather than absorb it. They are thick paints that protect the surface of the roof from UV rays.
Which materials you use for your cool roof will depend on the slope of your roof.
Flat or low sloped roofs
There are a few options for materials for flat or low sloped roofs:
- The first option is single-ply membranes that reformulate or coat black membranes to make them reflective.
- Next are built-up roofs that consist of base sheet, fabric reinforcement layers, and a protective surface layer. They can make them cool by using reflective mineral granules of factory applied coating instead of a dark coating, or by applying a cool roof coating on top of the dark asphaltic emulsion coating.
- You can make modified bitumen cool by pre-coating it with a cool roof coating.
- Lastly, spray polyurethane foam roofs rely on a protective coating that is already reflective, which allows them to perform as cool roofs.
Steep roofs
Steep roofs can use tiles and shingles to make them cool. Tiles can be slate, clay, or concrete and some are naturally reflective enough to perform as cool roofs. They can also be coated with surface treatments to transform them into cool roof material. You can buy cool asphalt shingles that use specially coated granules, or you can buy wood, polymers, or metal shingles that can be coated to make them more reflective. GAF Timberline® Cool Series Shingles, as shown in the image above, can provide potential energy savings and cost savings when you install them on your roof.
When you are deciding whether or not a cool roof is for you, you should weigh out the cost with the energy savings. Then you need to decide if you want to install a cool roof to a new construction home, coat an existing roof, or replace an existing roof with a cool roof. If you have any questions, please contact All Weather Tite in Port Charlotte, Florida. We will be happy to give you a free estimate on your new roof.