Although LEED and ASHRAE 90.1 (Energy Standard for Buildings Except Low-Rise Residential Buildings) standards require or reward use of white “cool” roofing to mitigate urban heat island effects, it is not always the best choice of material.
Cool roofs can cast heat where it is not wanted. “Architects and roof consultants need to be aware of potentially adverse thermal effects when choosing roof membranes, particularly where roof surfaces are adjacent to walls that can be affected by bounced sunlight,” says Elizabeth Grant, associate professor in the School of Architecture + Design at Virginia Tech.
Choosing the best material for a commercial roof is a nuanced decision requiring a careful examination of the application. “Roof selection is an architectural issue,” Grant said. “It’s not as simple as slapping a white roof on everything to gain a LEED point.”
The study compared the thermal impact of white and black roofs. The black roof heated the air within 5 ½ inches, but there was no difference in air temperature impact for black or white roofing above that zone. Researchers also found that electrical metallic tubing and glazed and precast concrete wall panels near white TPO roofing were 3 to 9 degrees Fahrenheit warmer than those near black EPDM roofing.
Related Stories
Codes and Standards | Feb 11, 2019
Investing in downtowns pays off for cities, regions
Benefits include driving tax revenue, business activity, and smart development.
Codes and Standards | Feb 8, 2019
Oslo, Norway’s downtown goes virtually car-free
Parking spots converted to bike lanes, transit is fast and easy.
Codes and Standards | Feb 7, 2019
New North Carolina energy code has extensive lighting control requirements
Includes automatic shut offs for buildings of all sizes.
Codes and Standards | Feb 6, 2019
Solar carports can help with California’s Title 24 mandates
Can be combined with virtual net-metering software and tax-enabled financing.
Codes and Standards | Feb 5, 2019
Milwaukee board approves rezoning for Western Hemisphere’s tallest mass timber building
Mixed-use tower would rise 21 stories high.
Codes and Standards | Feb 1, 2019
Mass. governor proposes real estate transfer fee hike for climate resiliency projects
Opposed by real estate and trade groups, plan could generate $1 billion in next decade.
Codes and Standards | Jan 31, 2019
New York City will reform construction bid process
Streamlined process intended to improve efficiency, reduce hassle for bidders.
Codes and Standards | Jan 30, 2019
New AGC program aims to diversify construction workforce
More diversity needed to keep pace with demand for workers.
Codes and Standards | Jan 29, 2019
Registration now open for LEED v4.1 for New Construction and Interior Spaces
Emphasizes human health and integrative building design.
Codes and Standards | Jan 25, 2019
AEC professionals should push for net zero projects
Educate and lead clients to more sustainable choices, says LEED fellow.