Issue link: http://digital.canadawide.com/i/177297
The Desmarais Building at the University of Ottawa is designed to collect natural light and distribute it into the facility's core. The precast concrete insulated wall panels use their thermal mass to collect heat/cool gains and transfer them to areas of need, maximizing natural heating. Photo courtesy Canadian Precast/Prestressed Concrete Institute (CPCI). Weapon of Choice The concrete sector takes on the competition, armed with the facts by Godfrey Budd W hen comparing the buildings with precast structures using cradle-tograve boundaries, those with the lowest global warming potential (GWP) are ones with precast concrete envelopes. The precast buildings with the highest GWP are those with curtain wall or brick envelopes. Comparing Toronto and Vancouver, as representative of the two most common climate types found in Canada, for a five-storey commercial building in Toronto with cradle-to-grave boundaries, 89 per cent of its GWP stems from its operating energy, nine per cent from its embodied energy, two per cent in maintenance, and a fraction of one per cent is construction and endof-life energy use. For its Vancouver equivalent, only 50 per cent of its GWP stems from operating energy, while 38 per cent represents embodies energy, 11 per cent is maintenance and, as in Toronto, a fraction of one per cent is construction and end-of-life. These are some of the Life Cycle Assessment (LCA) findings on precast concrete in a study by the Athena Sustainable Materials Institute for Canadian Precast/Prestressed Concrete Institute (CPCI). The study is compliant to the ISO 14040:2006 and 14044:2006 standards for LCA, says Brian Hall, national marketing director for CPCI. When members of the CPCI opted a few years ago to back the institute's then-proposed sustainability initiatives, which included the use of internationally recognized benchmarks and ISO standards to ensure transparency and objectivity, they were betting that the sector had a good story to tell. "Using ISO standards was the way to go. Why? There's too much greenwashing out there. It's time to be clear about the facts," says Hall. The aim of the LCA study was to better understand the environmental life-cycle performance of precast concrete in Canadian mid-rise precast concrete buildings relative to other structural and envelope systems. The intended audience includes architects, engineers, other specifying professionals, owners, developers, government and academe. CPCI members are working to be the first North American concrete manufacturers to achieve a thirdparty-verified Environmental Product Declaration (EPD). This provides details on a product's composition and environmental impact throughout its life cycle. "Not only will it encourage the choice of better products, it should spur the development and manufacture of better products. Awareness of EPD and related product information is to be promoted through ads. We want the specifying community to understand the sustainable attributes of our products," says Hall. A 32-page technical bulletin (CPCI-TRB#12-01) provides a range of professional information on the life-cycle assessment for precast concrete commercial buildings. It is backed by substantial research and volumes of data, says Hall. Besides transparency, he says the purpose of such documents along with other CPCI sustainability initiatives is to provide precise information, "rather than guesstimates," to stakeholders. While the Athena Institute conducted an LCA study and provided some software support, Morrison Hershfield developed the models for the Toronto and Vancouver reference buildings. "The model factors in a lot of fine detail. Morrison Hershfield developed some of the LCA methodology to incorporate ISO standards," says Don Zakariasen, director of marketing, concrete products, Lafarge A recent Canadian Life Cycle Assessment (LCA) found precast concrete insulated sandwich panels were a top-performing wall system. Remington Development Corporation is using the system on its Champagne condo project in Calgary, AB. Photo courtesy Lafarge Canada. Concrete p24-33Concrete.indd 25 11/16/12 3:22 PM