There is a global movement toward more energy efficient buildings, and at the crux of this movement are energy efficiency standards. These are recommendations or requirements (depending on the location or jurisdiction) that are in place to ensure that builders and contractors are using the most energy efficient designs and materials. Naturally, as a broad, exposed surface, a building’s roof plays a key role in energy efficient design, and modern roofing technology, like cool roofs, can be a major component to many of the current energy efficiency standards.
Specifications for cool roofs can be found in energy efficiency standards such as Title 24, LEED, ASHRAE 90.1, International Energy Conservation Code (IECC), and ENERGY STAR® because they not only help contribute to energy efficiency, but they can increase the roof’s life expectancy and reduce maintenance costs. Bear in mind, however, that many of these standards change every 3-5 years to accommodate new science, technology, and legislation. In some cases, a standard may even be retired when legislators feel its purpose has become redundant or obsolete – as has recently been (controversially) proposed for ENERGY STAR. ENERGY STAR roof products sunset proposal.
The ever-evolving standards and rapidly changing political climates can often make it difficult to keep track of which cool roof materials are compliant with the latest energy standards, and which standards are still in play. Fortunately, there is a fair amount of crossover between the goals and directives of the various standards, and as a result, meeting one standard’s requirement can often satisfy the needs of another.
This is the case with ENERGY STAR. While some are concerned that its absence may leave a gaping hole in the energy standard portfolio, the crossover between standards may be sufficient to fill the gap. This is why it’s imperative to understand the purpose of each of these standards, how cool roofs meet the requirements they set forth, and the potential influence of the political climate may have on the standard. Below, we’ve outlined some of the more prominent energy standards and how they apply to cool roofs to help demonstrate how your cool roof system may be a versatile solution to many energy efficiency standards.
ENERGY STAR is a voluntary program operated by the U.S. Environmental Protection Agency and the U.S. Dept. of Energy. Started in 1992, it’s now become the government-backed symbol for energy efficiency by businesses and local governments across the country. A key factor in the successful installation of a cool roof is emissivity, which is the measure of a substance’s ability to release absorbed heat. Though not currently a requirement for ENERGY STAR qualification, emissivity values for all certified products are recorded and publicly posted for consumers. Find more information about ENERGY STAR at https://www.energystar.gov/products/building_products/roof_products.
California’s Building Energy Efficiency Standards for Residential and Nonresidential Buildings, better known as Title 24, includes mandatory requirements for the thermal emittance, reflectance and Solar Reflectance Index of roofing materials used in new construction and reroofing projects. Cool roofs became part of the state’s energy code in 2005 after policymakers decided cool roofing was a way to ensure buildings operated as efficiently as possible. The purpose was to save on both energy output and the cost of keeping buildings cool and more comfortable for the people inside. This is especially important in the commercial sector of the roofing industry because the Title 24 regulations apply to jobs where over half of the roof or more than 2,000 square feet (whichever is less) needs replacement. More information is available at www.energy.ca.gov/title24/coolroofs.
The Leadership in Energy and Environmental Design (LEED) standards were developed in 2009 by the nonprofit U.S. Green Building Council (USGBC), and have since become a symbol for excellence in ‘green’ — or environmentally-conscious building around the world. The goal is to ensure energy cost savings by also reducing carbon emissions that harm the environment. Cool roof projects can earn LEED credits by adhering to standards across nine measurable factors applicable to most any building, including thermal emittance and indoor environmental quality. The USGBC’s newest version of the LEED rating system, LEED v4, became mandatory in 2016. Learn more at www.usgbc.org/articles/about-leed.
ASHRAE Standard 90.1 provides minimum energy-efficiency requirements for all buildings except low-rise residential structures. First created in 1975, there have been multiple updates over the years, including the latest in 2016 that reflects rapidly-changing technology in both the energy and construction fields. Though optional for energy code compliance, many states adopted the ASHRAE standards as mandatory parts of their permitting process. It’s an essential requirement to meet in commercial roofing since most states apply the standards for all commercial and government buildings.
The latest additions included roof solar reflectance and thermal emittance requirements for low slope roof systems. Learn more at http://docserver.nrca.net/technical/10174.pdf.
The International Energy Conservation Code (IECC) was developed by the International Code Council in 2000, and has become a model for energy regulations in the construction field adopted by many states, primarily in climate zones 1-3. The code specifically establishes minimum design and construction requirements for energy efficiency. Though different than CA Title 24 and ASHRAE 90.1, the standard now has a definition of low slope roofs that’s consistent with the others, and applicable to cool roofs.
Recent changes to the IECC include an addition in 2018 that allows minimum insulation thickness to be 1-inch less at the low point of a roofing system, which is typically a roof drain. Also, requirements for roof reflectivity apply only to buildings in climate zones 1-3 with a slope less than 2:12 and directly above a cooled space. More information is available at www.aikencolon.com/assets/images/pdfs/iecc/2015/2015-IECC-roofing-proposal.pdf.
These standards may seem complicated and lengthy as they are in place to cover multiple facets of the construction process, not just the roof. The table below helps break them down into which cool roof materials meet which standards.
Keep an eye out for our next article, which will go into more detail regarding why you shouldn’t panic about the possibility of ENERGY STAR going away, what cool roofs are, how does ENERGY STAR impact cool roofs and why the other standards are still effective with cool roofs.
For additional information, please contact:
Heidi Wollert, SBS, APP and BUR Product Manager