Findings from charter research projects at the two-year-old Concrete Sustainability Hub continue to validate longstanding industry claims on potential energy savings a home or building owner can realize with concrete structures. They surface as construction and real estate interests look beyond the style of green certification to the substance of hard energy-consumption numbers during a project’s use or operation phase.
A final report from the Massachusetts Institute of Technology-hosted Hub, Methods, Impacts, and Opportunities in the Concrete Building Life Cycle, confirms the positive role of thermal mass in residential and commercial buildings’ energy efficiency. Using Chicago and Phoenix properties to measure varied climate conditions, MIT faculty and staff compared the heating- and cooling-related energy consumption of insulating concrete form or conventional wood-framed homes, plus cast-in-place concrete and steel frame office buildings. Results show that the ICF-built homes in Chicago and Phoenix consume about 7 percent and 11 percent less HVAC energy, respectively, against the wood-built homes. The office buildings’ HVAC energy consumption figures show concrete exhibiting a potential savings of 7–9 percent; typical finishes and architectural treatments, however, lower the thermal mass factor and bring the concrete-favoring figure more in the 2–3 percent range.
Methods, Impacts was released last month in conjunction with the Concrete Sustainability Hub 2011 Industry Day (report, page 12), drawing upwards of 350 concrete and cement producers, plus representatives of national groups spanning production and practice. The report presents a unique, authoritative view of life-cycle assessments (LCA), according to officials from Hub sponsors, the RMC Research and Education Foundation and Portland Cement Association. It factors buildings’ cradle-to-grave cost and environmental impacts and fully measures embodied carbon dioxide levels at initial construction and those during the operation phase.
“Life cycle assessment is a valuable tool through which designers, policy-makers and consumers can understand how to lower the environmental impact of any structure,” Methods, Impacts authors contend. Indeed, architectural and engineering professionals, along with their customers, are looking more closely at life-cycle costs and CO2 emissions, especially given the initial-construction criteria to which the U.S. Green Building Council’s (Leadership in Energy and Environmental Design) LEED rating system is limited.
Hard numbers on concrete’s energy performance appear even more timely in light of issues raised in a federal lawsuit centered on LEED-certified buildings’ energy efficiency. Plaintiffs challenged USGBC claims from an April 2008 press release on results of a Council-sponsored study that indicated “new buildings certified under the LEED certification systems are, on average, performing 25–30 percent better than non-LEED certified buildings in terms of energy use.”
Led by a consultant in energy-saving building design, the plaintiffs alleged that USGBC claims were false and the study diverted customers from their businesses to LEED Accredited Professionals. They also alleged that the press release statement “harms consumers who may spend significant amounts of money on LEED certification but will not experience energy savings.”
Closing a case that had been considerably scaled back since its October 2010 filing, the U.S. District Court for the Southern District of New York found last month that plaintiffs lacked standing under a federal statute governing false representation of goods or service in commerce. While failing in court, plaintiffs nonetheless spotlighted voids in a widely subscribed rating system.
As operation phase energy consumption data takes hold among green-building practitioners, the concrete industry stands ready to show customers and certifying bodies proof of homework at MIT.