The first step in determining your roof’s energy efficiency is to determine the composition of your roof system. In most cases this requires a professional contractor to complete a core cut of the roof system. A core cut involves performing a cut of the roof system assembly to determine the overall composition of the roof assembly including the thickness of each layer of material. In addition, it is important to determine the type of decking that supports the roof assembly as this can have an impact on the energy performance of the roof system.
The second step is to determine the type and color of the exposed roof system. The energy performance of a roof system is dependent in part on the surface color and the material type. Each roof system type has a pre-determined rate of reflectivity and emissivity. Both of these characteristics help determine whether the membrane reflects solar energy or whether it absorbs it and if absorbed how long the material retains the energy. The greater reflectivity the less energy is absorbed which helps cut the transfer of radiant energy into the building. The lower rate of reflectivity, the greater the rate of energy absorption and the transfer of radiant energy into the building envelope.
he third step is to enter the composition of the roof assembly into a program designed to determine the energy efficiency of the roof assembly. There are several services offered through roofing manufacturers that help to determine the energy efficiency of roof assemblies. In addition, the NRCA has an online program for its members called Energy Wise
which allows roofing contractors to be able to determine energy efficiency of roof systems for their clients. In addition to the composition of the roof system, specific information pertaining to current heating and cooling appliances along with utility rates are required to further refine the feedback.
After determining the energy efficiency of the current roof assembly, many of the programs offer the ability to develop different options for improving the energy efficiency of the roof system. A professional roofing contractor utilizing these services can provide feedback for building owners and managers regarding how changes to the roof assembly will affect energy performance. Factors such as roof membrane color, increased insulation thicknesses as well as different insulation types can be considered. After developing these multiple scenarios, building owners and managers can then consider which option makes the most sense and produces the best return on their investment into the building.