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Sustainability Events

Heat Island Mitigation in the Broader Context of Urban Sustainability

David J. Sailor

  • Professor, Portland State University

One of the most commonly cited environmental effects of urbanization is the tendency of urban areas to be warmer than their unbuilt surroundings. This "urban heat island" (UHI) phenomenon has many adverse consequences, particularly in summer when it contributes to increased energy consumption for air conditioning, poor air quality, and higher risks for heat-related morbidity and mortality. As a result, many local and regional governments are pursuing efforts to reduce UHI magnitudes. This generally takes the form of increasing solar reflectivity (albedo) of roof and paved surfaces, increasing the availability of moisture for evapotranspiration (e.g., pervious pavements, green roofs, green walls), and providing street-level shading and evaporative cooling through tree planting programs.

A key assertion of this presentation is that governments are increasingly acting on limited and potentially flawed information to address issues of extreme summer heat and the resulting challenges to quality of life in cities. This rush to act to mitigate urban warming, while well-intentioned, may lead to policies that do not fully accomplish their intent. In the worst case, such policies can actually have unanticipated negative consequences, interfering with other sustainability goals. This presentation will begin by providing an overview of the causes and consequences of urban heat islands. It will then delve into some of the unintended consequences of UHI mitigation and suggest a path forward for improving urban climate outcomes.

This event is presented with the support of Barrett, The Honors College.

Tuesday, April 1, 2014
3:00 - 4:00 p.m.