Guide for Estimating Differences in Building Heating and Cooling Energy Due to Changes in Solar Reflectance of a Low-Sloped Roof.
An increase in roof solar reflectance results in a saving of building cooling energy and an increase in building heating energy. This guide provides data and calculation procedures for estimating the change in HVAC energy and resultant cost savings associated with changing the solar reflectance of low-sloped roofs. A brief consideration of exterior surface mass shows that the annual energy and cost savings are small compared to the effect of changing roof solar reflectance.
The two main purposes of white coatings are:
1) to protect roof membranes, resulting in longer roof life cycles.
2) to reflect solar radiation, resulting in lower energy costs. In general, a white coating consists of a binder blended with pigments and other additives.
There are literally hundreds of different white coating products, which are formulated and manufactured by many diverse companies. Most can be conveniently classified according to the binder they use.
Jefferson Houston Elementary School - An old, failing roof was replaced with a highly reflective, insulated, single-ply membrane roofing system.
The new roof resulted in increased comfort and substantial savings with no additional cost for the higher performance.
"We've been using this particular reflective product in a number of other schools. It goes on without odors, so we can install it while the kids are still in class. It is also easy to install, so it has become the material of choice for us."
Performance of Physical Structures in Hurricane Katrina and Hurricane Rita: A Reconnaissance Report
The two main purposes of white coatings are A number of spray polyurethane foam (SPF) roofing systems were observed in the Pascagoula, MS, area. Some of these roofs were estimated to be about 20 years old. With one minor exception, all were found to have sustained Hurricane Katrina extremely well without blow-off of the SPF or damage to flashings.
SPF roof systems have the longest documented performance periods of any insulated roofing system. Silicone coated systems have a proven performance record in excess of 20 years.
Dr. Dean Kashiwagi
Del E Webb School of Construction
Arizona State University