Expanding Your Options
Energy Initiatives Continue to Require Monitoring
by Richard K. Olson, President & Technical Director, Tile Roofing Industry Alliance
(Editor’s Note: Richard K. Olson is president and technical director for the Tile Roofing Industry Alliance. The association represents industry professionals involved in the manufacturing and installation of concrete and clay tile roofs in the United States and Canada, and works with national, state, and local building officials to develop installation techniques, codes, and standards for better roofing systems. Olson can be reached at rolson@tileroofing.org.)
For the design professional, the topic of energy savings of roof assemblies can be challenging as there are many aspects to consider in steep slope applications. As an industry association, the Tile Roofing Industry (TRI) Alliance is constantly monitoring the proposed changes at the local levels for both code and legislative influences. In recent years there seems to be a focus by organizations to attempt through legislative actions, to mandate that a white roof is the only way to help energy reduction. We are seeing this play out in certain geographic regions where legislative actions have been proposed. The TRI Alliance, in collaboration with other industry associations that represent builders, roofers, and cladding product materials have joined forces to help educate and refute the theory that only a white roof cladding should be allowed. The TRI Alliance is supportive of finding more energy efficient roof assemblies. A white roof, one size fits all approach, is not the answer, nor does it present the full scope of options.
When designing energy efficiencies in steep slope applications there are several compliance options that the codes allow. Color is just one aspect of the design options or tools that are available. Organizations like the Cool Roof Rating Council provide third party ratings for the Solar Reflectance of various roofing materials. When aged on weathering farms for three years they are assigned a three year Solar Reflective Index (SRI) value. For new products there is an initial rating and method to calculate an SRI for designers to use. The higher the SRI, the greater the material will be in reducing heat transfer through the system based upon one aspect, color. While white would provide the highest potential SRI, it is limited in availability for most cladding products that can provide equal field performance. On steep slope applications in humid climates there is formation of fine dirt, algae, mold, or other growth affecting the color white. In other regions the buildup of pollutants, silt, dirt and vegetation can occur. Even with pressure washing, it is hard to maintain a white roof as regrowth occurs on a regular basis.
For our concrete and clay tiles, there are energy saving attributes beyond color that can be incorporated into the energy discussion. In many cases these benefits will provide greater energy savings than the color-based ratings of other cladding materials. Our materials are rated at the CRRC, but again these are just color-based ratings to allow comparison to other materials that only have color as an attribute.
In looking at similar SRI ratings of roof cladding options, you will see for instance that an orange-colored clay tile will be greater in SRI ratings versus a very light colored shingle. As the design professional we need to look at the actual colors of our materials when selecting our roof claddings as their ratings and colors are not equal across the rating lists.
The pure mass of our tiles, compared to other products, increase the natural insulative properties that will reduce the transfer of heat through the cladding. Department of Energy studies have shown up to 70% reduction compared to shingles. For the consumer this will equate to actual energy cost savings and can help move the peak time demands in areas of tiered energy costs. In colder climates the mass of the tile can help in reverse by holding daylight heat in the tile for longer timeframes.
We have talked in previous articles about the attributes of above sheathing ventilation for roofing tiles or any system that allows the natural airflow on steep slope application. As air exits the top of the roof assembly, ambient air is drawn into the eave creating a natural airflow. This air barrier provides an insulative barrier to increase energy efficiency.
We are seeing an increase in the use of radiant barriers in areas where new construction, or even a reroof is using material preferences that opens a greater color selection for the claddings. In the past year there have been new underlayments that have entered the market that bring insulative properties through increased thickness of fiber materials. For the design professional it is important to look at all the available energy options and to review the manufacturers information for how to best install a roof assembly to gain the greatest benefits for your building project
As an industry association we are here to help educate and provide resources for information on the topics of energy efficiencies. We are commencing a formal research project to quantify the consumer savings of our roofing tiles in the ten code defined climate zones in the country. This study will gather data for three years to better understand the full benefits of the various tile installation configurations.
