More commercial developers and owners of commercial buildings are installing “cool” roofs to increase the life of the roof and potentially lower operating costs.
Conventional flat roofs are black, and black materials absorb more heat, leading to warmer building. A cool roof is lighter in color and made of materials that tend to reflect light and heat. The result is a cooler building, which cuts air-conditioning costs in the summer. In fact, on a hot day, a black roof can be 70 degrees hotter than the air temperature, compared with only 20 degrees hotter for a cool roof.
In the past, some in northern climes have resisted cool roofs because they were thought to increase heating costs in the winter. Now a recent study of cool and conventional roofs by the Lawrence Berkeley National Laboratory has found that in virtually the entire country, the summer air-conditioning savings of cool roofs are greater than the increased heating cost in the winter.
There are other benefits of cool roofs that make them attractive, particularly for commercial structures:
- Cool roofs tend to last longer because they suffer less thermal stress than conventional roofs do.
- Cool roofs reduce the urban heat island, because the building structure is cooler. The heat island effect in one of the causes of the formation of smog and greenhouse gases.
- A cool roof helps a building qualify as environmentally friendly by the U.S. Green Building Council, which is of interest to a growing number of tenants.
Cool roofs typically cost the same or only slightly more than conventional roofs to install.
Gray, Thomas O. AIA, DRS Architects. “Cool Roofs are Hot.” Post-Gazette Now
3 Sept. 2008. Business. 3 Sept. 2008 <http://www.post-gazette.com/pg/