Last month, The National Roofing Contractors Association (NRCA) updated its EnergyWise Roof Calculator. The online tool now includes information from the 2015 version of the International Code Council’s International Green Construction Code and the 2013 version of ASHRAE Standard 90.1 (“Energy Standard for Buildings Except Low-Rise Residential Buildings”). Other adjustments were made to the online calculator.
Joan Crowe, The NRCA’S Director of Technical Services told Energy Manager Today that to date about 3,700 contractors and other interested parties have registered to use the calculator and that it has generated almost 8,000 reports. It doesn’t provide information that can’t be garnered through other means, Crowe said. It is a tool that consolidates and adds convenience.
The free tool, originally called “RoofWise, The Energy Workbench,” was launched in 1998. It provides four benefits, according to Crowe. The tool:
- Judges compliances of the roof in the context of the codes and regulations for that particular municipality;
- Estimates the R-value (a measure of thermal resistance) for the materials and insulation selected;
- Assesses the thermal gradient of the roof;
- Provides a very rough estimate of heating and cooling costs based solely on the roof infrastructure.
Roofs are difficult to discuss collectively, because there are many different types, from residences to tall office buildings. In addition to the vast differences in mechanisms between a building and a house, geography plays a role. For instance, a roof in a warm southern environment would be more reflective than one in a colder northern area.
However, Crowe did offer one universal suggestion: People should pay attention to their roofs.
The basics of roofs are not changing. However, insulation requirements tend to grow more demanding over time and some of the details shift in subtle but important ways. “People want a proven time-tested roof system,” Crowe said. “We always tell home owners and building owners when to stick with something with a proven track record. In terms of synthetic systems we don’t know how long they will last. They often are made of recycled material and you have to be careful when install those.”
The NRCA recommends that property owners inspect their roofs twice annually and after major weather events. This should be done by professionals who understand what to look for – and who are accustomed to being on roofs, which are inherently dangerous places. Crowe said that roofing inspectors will look for debris, pooling water, delamination or a deterioration of materials.
The growth of rooftop solar voltaics raises an important issue for building owners and energy managers. These panels have long lifespans. An easily made mistake – and a very costly one – would be to install them on a roof that is near the end of its lifespan. Thus, coordination between the age and state of repair of the underlying roof must be a main consideration when a solar project is being planned.
In general, Crowe points out, the installation of panels on roofs requires penetration, which is something that is frowned upon by roof experts. Likewise, skylights must be installed with proper flashing, which is the manner in which the window is installed.