Today we build on prior blog posts about energy-efficient buildings and the role reflective roofing can play in improving building energy performance. One option that has emerged as a way of reducing solar heat absorption is the “cool roof system,” which uses reflective roofing materials to help keep roof surface temperatures lower.
But how exactly does a cool roof system provide benefits?
Below, we take a quick look at how a cool roof can benefit building owners and, in some cases, the surrounding environment.
The Cool Roof and Its Consumer Benefits
- Cool roofs have high reflectance and emittance values. Reflectance describes how much solar energy a roof reflects, while emittance describes how effectively the roof releases absorbed heat. Cool roofing materials are designed to reflect more solar energy and release more absorbed heat than many darker roof surfaces. As a result, less heat may transfer into the building below, which can reduce cooling demand and improve indoor comfort in some buildings. Actual energy savings depend on climate, insulation, HVAC efficiency, roof construction, building use, and the specific roofing system.
- Cool roofs may reduce a building’s environmental impact. When a reflective roof helps reduce cooling-related electricity use, it may also reduce the environmental impact associated with that energy consumption. Lower roof surface temperatures can also reduce some forms of temperature-related stress on roofing materials.
- Cool roofs can contribute to broader heat-reduction strategies. Reflective roofing is one of several approaches that may help reduce heat absorption in developed areas. The effect on local temperatures, air quality, and public health depends on many factors and should not be attributed to any individual roof alone.
- A cool roof may reduce electricity demand during hot periods. By reducing solar heat gain, a reflective roof may lower cooling demand during some of the hottest parts of the day. Buildings with demand-based or time-of-use electricity pricing may see additional value from reducing energy use during peak periods, although actual savings vary by building and utility rate structure.
It is clear that a cool roof system can offer meaningful value through lower roof surface temperatures, reduced solar heat absorption, potential cooling-energy savings, and other building-performance benefits. The actual results depend on the roof system, climate, insulation, building use, and other project-specific factors.
Additional Cool Roof Benefits and Considerations
Cool roof systems can include reflective membranes, coatings, and other roofing materials designed to reduce solar heat absorption. Some coating-based systems may also be used to restore an existing commercial roof when that roof is structurally sound and otherwise suitable for restoration.
A properly selected and installed reflective coating system may provide a continuous protective surface over properly prepared roof areas and help extend the useful life of an existing roof. However, coatings should not be expected to eliminate every future leak, correct serious structural problems, or provide the same performance in every application.
Before restoration, the roof should be evaluated for wet insulation, structural deterioration, drainage problems, failed seams or penetrations, damaged roofing materials, and other conditions that may need to be corrected first.
Reflectivity, durability, weather resistance, warranties, maintenance requirements, and expected service life vary by roofing product and system. These characteristics should be evaluated using current manufacturer documentation and the conditions of the specific project.
A commercial roofing contractor can inspect the existing roof and discuss whether a cool roof coating, repair, restoration, or replacement is appropriate for the building.
For more information, visit our Cool Roof Systems page.
