EVALUATING THE BENEFITS, SUSTAINABILITY, AND RESILIENCE OF GREEN INFRASTRUCTURE ON A SUSTAINABLE RESIDENTIAL HOME

Abstract

With global populations becoming increasingly urbanized, green infrastructure (GI) is progressively being recognized as a sustainable approach to mitigating urban environmental problems. Unlike traditional ‘hard’ engineering approaches that historically viewed problems in isolation and solutions in singular terms, implementation of GI promises some deferment from the effects of urbanization by providing a multitude of benefits such as reduced stormwater runoff and flooding, decreased heat waves, and enlivened local environments and ecological habitats. These benefits are important considering many cities are projected to be more vulnerable to the effects of urbanization with climate change, especially as the vast amount of the global population lives in coastal urban environments.

However, the diversity of GI benefits has not been fully characterized, and they are increasingly applied in residential settings. Furthermore, current research has not fully explored the beneficial role of GI in achieving sustainable and resilient communities.

Using an Integrated Water: Energy Monitoring System measuring meteorological, water, and energy fluxes over two years (July 2014-June 2016) on a sustainable home in Rockville, Maryland, U.S., the following objectives were explored:

(1) Examined how a sloped modular extensive green roof, constructed wetland and bioretention designed in-series affected site hydrology. Furthermore, we studied the effect of season, antecedent substrate water content, storm characteristics (size, intensity, frequency), and vegetation development (green roof only) on hydrological performance.

(2) Characterized the seasonal thermal performance of the green roof (to the building and surrounding environment) relative to the cool roof. Evaluated how green roof thermal performance related to evapotranspiration, solar reflectance (albedo) and thermal conductance (U-value). Additionally, the effect of substrate water content, vegetation development, and microclimate on evapotranspiration, albedo and U-values was assessed.

(3) Green roof evapotranspiration was measured and compared to values predicted with the FAO-56 Penman-Monteith model. Furthermore, the effects of substrate water content, vegetation characteristics and microclimate on evapotranspiration rates was also evaluated.

(4) Finally, using emergy theory, GI sustainability and resilience relative to a gray wastewater system and natural forest was explored.