Building Energy Technology: Guidelines for Selecting Cool Roofs

Fraunhofer Center for Sustainable Energy Systems

A cool roof system.

Project Motivation

Cool roofs are designed to maintain lower roof temperatures by reflecting sunlight and allowing more heat to be emitted from the building below. By reducing roof temperature, cool roofs cut the amount of heat that enters the building, lowering the amount of air conditioning and ventilation needed to keep occupants comfortable. 


Working on behalf of the US Department of Energy and Oak Ridge National Labs, Fraunhofer CSE's researchers assembled a guide to help building owners understand how cool roofs work, what kinds of cool roof options are available, and how to determine if cool roofing is appropriate for a particular building. 

 

Benefits of Cool Roofs

A cool roof can be desirable to a building owner for several reasons. Cool roofs can reduce energy bills by decreasing air conditioning needs, improve indoor thermal comfort for spaces that are not air conditioned, and decrease roof operating temperature, which may extend roof service life.


In many cases, cool roofs cost about the same as non-cool alternatives. The energy cost savings you can realize from a cool roof depends on many factors, including local climate; the amount of insulation in your roof; how your building is used; energy prices; and the type and efficiency of your heating and cooling systems.


Cool roofs can also provide benefits to the environment. Cool roofs can reduce local air temperatures, which improves air quality and slows smog formation; reduce global warming by reflecting more sunlight back into space; reduce peak electric power demand, which can help prevent power outages; and reduce power plant emissions, including carbon dioxide, sulfur dioxide, nitrous oxides, and mercury, by reducing cooling energy use in buildings.