EPDM Roofing Systems Are An Energy Efficient Option

Commercial EPDM Single – Ply Roofing System Part 2

EPDM roofing membrane accounts for more than 1 billion square feet of new roof coverings in the United States each year. Today, there are well over 500,000 warranted roof installations totaling more than 20 billion square feet of EPDM membrane in place nationwide.

However, when seeking a “cool roofing” option, many building professionals do not realize that black EPDM provides similar energy savings as its white, non-EPDM, counterparts. A cool roof, as defined by the California Energy Code, is a roof covering or surface that has been tested and labeled by the Cool Roof Rating Council as having an initial solar reflectance of a least 0.70 and an initial thermal emittance of at least 0.75. So where exactly does ballasted roofing fit among cool roofing options?

A three-year study initiated by the Single Ply Roofing Industry (SPRI) and conducted by the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) was completed in 2008 and provided extensive analysis of the energy performance of ballasted systems. As part of the study, titled Evaluating the Energy Performance of Ballasted Roof Systems, six roof panels – four ballasted EPDM featuring different stone/paver ballast weights and two control panels (a white TPO and a black EPDM membrane) – were subjected to daily weather cycles side-by-side from March 2004 through April 2006.

EPDM Roof System

EPDM Roof

Among the key findings:

  • The cooling loads for the heavy and medium stone-ballasted and uncoated paver-ballasted systems were approximately the same as for the white system.
  • Cooling loads for the lightweight stone systems were slightly larger than for the white system but significantly less than for the black system.
  • By the start of the second year of the project, temperature and cooling loads increased for the white system due to the effects of weathering.
  • Heating loads for the ballasted systems showed random variation as loading increased and type changed. Except for the heavyweight stone system, they were about the same as for the white system.
  • The heavyweight stone system showed slightly less heating load than the black system but this is considered an anomaly due to rain effects.
  • All evidence on clear days of diurnal behavior showed the heavyweight stone and uncoated paver systems performing equally due to the same thermal mass despite different solar reflectance.

The study further revealed that the ballasted EPDM profiles offered better thermal emittance properties. While solar reflectance measures how well a roofing material reflects sunlight, emittance measures the roofing material’s ability to release absorbed heat back into the atmosphere, rather than into the building. Both are important properties that help a roofing system remain cool.

In the study, the ballasted EPDM profiles delayed the temperature rise for up to three hours, effectively moving about 20 percent of the cooling load into off-peak hours of the day when energy costs are lowest. Summarizing the study’s results, AndrĊ½ Desjarlais, program manager of the Building Envelopes Program at ORNL, stated that certain ballasted roof systems “are as effective as white-membrane roofs in mitigating peak energy demand.”

As a result, several regulatory bodies across the country have adopted new standards in regard to cool roof materials. For instance, the California Energy Commission has approved the use of ballasted roof systems as a cool roofing option as part of its 2009 Title 24 energy standards. And, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has tentatively decided to update its cool roofing standards and will recognize ballasted roof systems as an acceptable alternative to light-colored materials. Likewise, the city of Chicago, which has earned international accolades for its commitment to sustainable roofing practices, has added ballasted EPDM as an accepted cool roofing alternative in its municipal code for low-sloped roofs.

Talk to a Minnesota commercial roofing contractor to find out if an EPDM roof system is the right choice for your building.

Source: arwmag.com
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4 Responses to “EPDM Roofing Systems Are An Energy Efficient Option”

  1. Elizabeth Says:

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  3. roofing company vancouver Says:

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  4. johnny Says:

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