A new report from the Massachusetts Institute of Technology-hosted Concrete Sustainability Hub (CSHub), Critical Issues When Comparing Whole Building and Building Product Environmental Performance, addresses key concepts in quantifying the environmental impact of buildings and products comprising them. It also makes recommendations for current and future building practices using life cycle assessment (LCA), and offers suggestions for research to advance future study and practice.
|The report is posted at cshub.mit.edu.
“Buildings are complex,” says MIT Professor and CSHub Executive Director Jeremy Gregory, report co-author. “To understand the full environmental impact of a structure over decades of use, all phases—starting before construction and continuing on to the very end of the structure’s life—must be considered.
“One of the key takeaways is that there are many factors that must be considered before evaluating claims that one or another building type or product offers a better environmental return. Decision-makers must take a life-cycle perspective when evaluating impacts. One material may have a higher impact at the outset but result in a much lower impact across a structure’s lifespan.”
Building sector guides, product category rules, and environmental product declarations that use LCA to evaluate environmental impacts, including guidelines set forth by the Leadership in Energy and Environmental Design (LEED) rating system, he adds, have moved the industry forward. However, the prevailing methods have limitations: They lack consistency in their approach and do not allow whole buildings or even building products to be compared against alternatives.
“The ability to compare one building type to another, or one product choice with another, is extremely important so that decision-makers fully understand the benefits or consequences of shifting building designs and technologies,” Gregory contends.
Like past CSHub research documents, Critical Issues advocates for the development of a standardized buildings framework, which researchers feel is essential in order to increase LCA approach accuracy, while adding a call for comparability. The new research is part of ongoing work by the CSHub, which has undertaken a series of projects quantifying buildings’ full life cycle impacts.
“There is significant inconsistency in the way that many life-cycle assessment studies consider, or in some cases ignore, the life-cycle stages of buildings,” notes MIT Materials Systems Laboratory principal research scientist Randy Kirchain, CSHub co-director and report co-author. “This report tries to highlight where inconsistencies often are found and identifies best practices to address those aspects of buildings LCA. Work at the CSHub and by many other LCA experts has made it clear that without a full life-cycle assessment, the picture is incomplete.”