Evaluating the Influence of Ecoroof Surfaces on Indoor Air Quality

Portland State University, Portland OR

Investigators

Abstract

1605843 Starry, Olyssa Americans spend 90% of their time in buildings, resulting in exposures to air pollution being largely dictated by indoor air quality. One key determinant of indoor air quality is ventilation of indoor spaces with outside air. Increased rates of building ventilation have been correlated with improved occupant health, satisfaction, and productivity. However, improved indoor air quality, from increased ventilation, is ultimately contingent on the quality of outdoor air. Ecoroofs are an increasingly popular strategy for improving building sustainability that result in vegetated building surfaces that may be in close proximity to a building?s outdoor air supply (often rooftop). While air quality models indicate that ecoroofs may remove substantial quantities of air pollutants from urban atmospheres, no empirical studies are known that investigate how an ecoroof may affect the indoor air quality of the same building. Urban air quality studies of ecoroofs typically consider only deposition of air pollutants, however, there is precedence for vegetation to emit volatile compounds that may degrade indoor air quality or participate in secondary chemistries which results in the formation of irritating or harmful air pollutants. Therefore, there is a need to critically and holistically evaluate source, sink, and transformations of air pollutants at vegetated ecoroof surfaces. Examining how ecoroofs may impact indoor air quality is critical for developing more sustainable building designs and for identifying synergistic opportunities to enhance the sustainability of the urban environment. This research will investigate the effects of ecoroofs on indoor air quality with a holistic approach that addresses two fundamental, yet interrelated research questions: 1) How does the design of a building rooftop affect deposition, processing, and emissions of air pollutants? and 2) How might ecoroofs affect indoor air quality? This project will address these questions with a combination of extensive and innovative data collection that integrates ecology, biology, and building science approaches. Specific investigations will include a broad field survey of 48 roof surfaces in Portland, OR, an intensive air quality monitoring study at a commercial facility with a dual ecoroof/white membrane roof, and bench-scale laboratory investigations. Field measurements and laboratory parameterizations will be used in statistical models and material balances to explain relationships between the urban environment, ecoroofs, and indoor air quality. This project will provide data that leads to an improved understanding of ecoroof-indoor air quality interactions. The data, parameterizations, and models from this project will inform building sustainability practices by enabling indoor air quality impacts to be integrated into ecoroof and urban green-surface design. Study outcomes will help identify opportunities to improve indoor air quality and reduce human exposure to air pollutants. The project will work closely with the City of Portland and the local Greenroof Information Thinktank (GRIT) to engage the community in this work and disseminate results to the public as well as industry.