Cool roofs are one of the fastest growing sectors of the building industry. Building owners have come to understand the short term and long-term benefits of cool roofs for their own needs as well as the community around them.
What is a cool roof?
A cool roof is any roofing product that is designed to reduce heat absorption. These products have cool roof coatings which are white or have special reflective pigments that are typically light colored and can be used in commercial or residential application. These coatings are like a very thick paint that provides ultra-violet protection, chemical protection and some offer water protection. Today, there are products for every roof type.
What are the benefits of cool roofs?
Studies have shown that cool roofs reduce heat absorption, which helps to decrease the cost of cooling buildings. In the 80’s, The Department of Energy laboratories completed studies to determine the energy savings. Although the initial results were not substantial enough to motivate a change in thinking for the roofing industry, data that has been compiled since shows a substantial cost savings of 15% in cooling buildings. For buildings that do not have cooling systems, these types of roofs can cool the indoor air temperatures making for a more comfortable work environment.
The Department of Energy ran an additional study and released data that shows that in an urban environment, cool roofs help to reduce impact of the “urban heat islands”. Cool roofing reduces peak demand for electricity which helps to limit blackouts and power surges.
With the reduced demand, the negative environmental impact of fossil fuel generated electricity can be decreased. As an added benefit, increased use of cool roofs may potentially slow global warming by cooling the atmosphere.
How do cool roofs work?
Traditional dark colored roofing materials absorb heat, which then heats up the building beneath. The use of white or specific colored roofs are reflective of the sun’s heat. Since the roofs stay cooler, there is less heat in the building reducing cooling costs; or in the case of a building with no cooling system, the building naturally becomes cooler.
There are two properties of a roof which determine the cooling rating:
Solar reflectance, which is the portion of the reflected sun.
Thermal emittance, is the efficiency at which a roof cools down by emitting thermal radiation.
Both of these properties are rated from 0 to 1. The higher the number the cooler the roof.
Are cool roofs costly?
If you are installing a new roof or replacing one, a cool roof does not have to cost more than a non-cool roof. However, if you are converting a standard roof that is in good condition, the process could be expensive. There are specific cool roof costs for specialized materials and labor. In the long term, however; a cool roof can save money in energy savings, rebates and other incentives, HVAC downsizing and extended roof lifetime