Reducing environmental impact with green buildings

Reducing environmental impact with green buildings

Adherence to three green building code and certifications systems demonstrates on average a 14-percent reduction in the environmental impact of a typical office building, with LEED results displaying worrisomely high variability in performance.

Original Paper:
Suh, S., Tomar, S., Leighton, M., and Kneifel, J. 2014. Environmental Performance of Green Building Code and Certification. Environmental Science and Technology. 48. 2551-2560. DOI: http://dx.doi.org/10.1021.es4040792

Green building code and certification systems have proliferated recently as communities attempt to reduce the environmental impacts of the built environment. While these programs are gaining in popularity, the assumption that they actually reduce impacts remains poorly tested. Distinguishing between real environmental gains and "green-washing" will determine the ultimate success and longevity of efforts to green the built environment. A recent paper quantifies the environmental benefits of three prominent building code and certification systems using life cycle assessment (LCA) methodology. It shows that basic adherence to the three systems — Leadership in Energy and Environmental Design (LEED), ASHRAE 189.1, and the International Green Construction Code (IgCC) — reduces environmental impacts on average between 0 and 25 percent across 12 environmental impact categories.
 
In the study, published in the journal Environmental Science and Technology, the researchers assessed over 380 different materials for environmental impacts. In general, a limited number of components were found to contribute the vast majority of the environmental impact. Electricity, tap water consumption, and employee commuting during the use phase were shown to dominate 10 out of 12 impact categories — including global warming potential, human health measurements, eutrophication, acidification, water use, and smog formation. Interestingly, impacts on ozone depletion were spread much more evenly across a wide selection of material inputs. Wood products contributed the majority of land use impacts. 
 
A standard office building construction as defined by NIST was used as the starting point for the comparison. The design of the baseline building was altered according to input from the referenced green building code or certification system. Different criteria from these systems affected the inputs and outputs of building construction, maintenance, operation, and end-of-life disposal. Not all criteria included in the LEED, ASHRAE, and IgCC code and certification systems are able to be measured using current LCA methods.
 
They found that requirements built into the three green building code and certification systems improved environmental performance by 15 to 25 percent, and improvements were found in 10 of the 12 assessed impact categories. Given the contribution of buildings to global environmental impact this reduction should be viewed as significant. However, green building certification systems did little to reduce impacts related to land use and ozone depletion; in some cases they resulted in marginally higher impacts. An important caveat to the result regards the ability of the building design and certification team to choose which credits to pursue under the LEED system. Under certain combinations of credit selection the environmental gains of pursuing LEED certification can be reduced to zero. Overall, it is shown that pursuing interventions to reduce energy consumption realized the largest environmental benefit. 
 
The paper is the result of a collaborative effort between researchers at the Bren School of Environmental Management, Industrial Ecology Research Services, and the National Institute of Standards and Technology (NIST). 
 
To some extent, the results of this study are limited by the current ability of LCA methods to measure environmental impacts. Evaluation of indoor air pollution, urban heat island effects, and light pollution are three examples of improvements incentivized by the reviewed building code and certification systems that are not adequately captured by LCA. The ability to measure such benefits in the future is an important avenue for further study. The validity of green building code and certification systems depends upon their achievement of tangible environmental gains, which amplifies concern regarding the variable performance of LEED buildings. And although we may ask if 15 to 25 percent improvement is enough to reach global sustainability goals, we should take solace in the fact that it is improvement. As these frameworks mature we can expect gains to increase over time as well.

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