Green Building Products

Calculating Energy Savings From a Green Roof is a Job for Experts

Calculating the R-value of manmade insulating materials is a straightforward process. For green roofs—not so much. “The equations that describe energy transfer through evaporation, reflection, convection, and thermal mass can get ugly,” says Chris Wark, Senior Energy Analyst, Viridian Energy & Environmental. That’s because a green roof isn’t a static object. It is alive.
Jan. 6, 2011

Calculating the R-value of manmade insulating materials is a straightforward process. For green roofs—not so much.

“The equations that describe energy transfer through evaporation, reflection, convection, and thermal mass can get ugly,” says Chris Wark, Senior Energy Analyst, Viridian Energy & Environmental. That’s because a green roof isn’t a static object. It is alive.

“A green roof does not just sit there resisting heat flow, it is an active energy device, literally collecting, processing, and releasing energy according to its immediate need, just like all other living things, including people,” Wark points out. “Now for a good rhetorical question: What is the R-value of a human?”

Projecting future energy savings from the installation of a green roof is not something for the average human, Wark says, no matter what his or her R-value. For an accurate estimate, hire an energy analyst who understands green roof thermal properties to model the building and conduct a proper roof treatment study, he recommends.

About the Author

Drew Ballensky

Drew Ballensky is general manager of Duro-Last Roofing, Inc.’s central U.S. facility in Iowa and company spokesman for Duro-Last’s cool roofing, sustainability and architectural education programs. He is past-president of the Chemical Fabrics and Film Association and chairman of CFFA’s Vinyl Roofing Division. Drew earned his bachelor’s degree in industrial technology from the University of Northern Iowa and master’s degree in business administration from Florida State University. Drew has over 29 years experience in business and industry in various engineering and managerial capacities. He has worked in the U.S. and Canadian operations for a major international manufacturer of pre-engineered steel buildings, was a financial analyst with a major athletic apparel manufacturer and was an owner of a general contracting company.
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