People have long noticed that using light-colored building materials on a roof reduces the temperature in the building beneath. Just as a white shirt is cooler on a summer day than a dark colored shirt, light-colored roofs can make a significant impact on the energy efficiency and comfort inside the building they cover. New technologies and materials available in the building industry have created cool roofs with more options in colors and designs.
How Cool Roofing Materials are Rated
How much a roofing material adds to cooling of the building is measured on two scales. One measure is solar reflectance (SR) which rates how well the material reflects heat without absorbing it. The other measure is thermal emittance (TE) which measures how well the material lets heat escape from the building under the roof. Both scales go from 0 to 1, and a higher rating means better reflection and escape of heat.
The Cool Roof Rating Council, or CRRC, is an organization which tests roofing materials and gives them a rating for SR and TE. These results are then published in their online Rated Product Directory, available at no charge to the public. The Directory lets you compare different roofing products and determine their coolness rating.
A study done by the Lawrence Berkeley National Laboratory found that a white roof has a solar reflectance rating up to 0.4 higher than dark-colored roofing materials, using the CRRC scale. The study estimated a 10 billion dollar annual reduction in energy costs in the State if metropolitan areas converted to cool roofs.
How a Cool Roof Can Benefit Your High Desert Property
Covering a roof with cool roof materials can do the following:
- Lower summer utility bills,
- Increase the life-span of AC system,
- Improve the comfort level inside,
- Extend the life-span of the roof and lower repair costs,
- Contribute to reduction of local urban heat island effects,
- Improve the aesthetic appeal of the roof and add value to the property,
- Possible rebates for installation.