The Department of Energy's Argonne Laboratory has determined that using certain roofing materials can lower temperatures on the outside and inside of buildings, reducing the need for air conditioning and lowering energy costs.
This past summer, the world experienced the highest temperatures on record, according to scientists, and communities are looking for strategies to address extreme heat, especially in urban areas. Many cities contain a large amount of concrete and brick buildings, traffic, and steel infrastructure that absorb and re-emit the sun’s heat more than natural landscapes. This results in the urban heat island effect, which causes cities to experience higher temperatures than their surrounding area.
Since cities are densely packed with buildings, using cool roofing offers a solution to lower temperatures for residents in practically all areas of a given city. The Argonne lab explored the effectiveness of three types of cooling roof materials in a simulation of the Chicago area: heat-reflecting white paint, vegetation, and solar panels.
Cool roofs were found to have the most effective cooling effect, followed by vegetation, then solar panels. Cool roofing lowered building energy demand by about 16.6%, while solar lowered demand by 14%, and solar panels by 7.6%.
Cool roofing was also found to be the best option for large-scale deployment as it costs less than the other two technologies and does not require water or extensive maintenance.
Cool roofs work by reflecting more sunlight than a conventional roof, so they absorb less solar energy, lowering roof temperatures by as much as 50 degrees on a hot, sunny summer day.
Along with cooling roof technology, a number of heat-reducing strategies are being developed and tested for the ability to lower urban temperatures.
One such solution is a simple, nature-based fix: planting trees. A modeling study done earlier this year found that increasing tree cover in urban areas can decrease heat-related deaths and reduce temperatures by about .4 degrees. Shade provided by trees and other vegetation can also work to cool buildings in urban areas, reducing energy costs and the need for AC. Some cities have also explored the use of cool pavement, which reflects solar energy and enhances water evaporation in order to remain cooler than conventional pavement.
Urban planners, governments, and individuals may use the findings from this Argonne study to inform both present and future heat mitigation strategies.
