Mitigating urban heat islands to save cooling energy use, improve urban comfort and air quality, reduce heat-related mortality, and counter global warming

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Summary of Proposal During the summer, cool roofs and cool walls reflect most of the incoming sunshine and reduce heat conduction through roofs and walls. Similarly, strategically placed trees, shading windows and walls of a building reduce the direct heat gain. The reduction in summer heat gains reduces the air-conditioning load of a building, improves comfort, saves peak demand electricity, and save money. During the winter, cool roofs and shade trees may add to the heating load of a building, however, the heating energy penalties are fairly small (trees can actually save heating energy bills by shielding a building from cold wind). Summertime temperatures in many Canadian cities have been steadily increasing with expansion of the city. Also, most new buildings are equipped with air-conditioners; as a result the local utility companies are experiencing significant summertime peak load. Cool urban surfaces together with vegetation can potentially cool down the city by a few degrees, further reducing cooling energy demand, improve ambient air-quality, and reduce summertime heat stress related mortality. Increasing the solar reflectance of urban surfaces, increases reflection of short-wave radiation back to space. This process of "negative radiative forcing" counters global warming. IPCC estimates that increasing the solar reflectance of a m2 of surface by 0.01 cools down the globe equivalent to reducing CO2 emissions by 7 kg. Increasing the reflectance of 50% urban areas by 0.10, cools down the world equivalent to 130 Gtonne of CO2 (~ 50 years of emissions from all cars in the world). The objective of this program is to perform basic and applied research addressing energy efficiency and air quality appropriate to Canadian cold climates, buildings and communities. We will: Perform detailed analysis to characterize effects of cool surfaces and vegetation on building and community energy use and urban air quality; Develop detailed land-use databases for several Canadian cities (obtain high-resolution orthophotos and perform statistical analysis to characterize urban fabrics); Develop guidelines for installing cool roofs, cool pavements, vegetation; Develop climate- and regional-specific cool roofing and cool paving materials appropriate for Canadian climate ; Conduct research on the impact of heat islands and mitigation technologies on ambient air quality, citizen comfort, and summertime heat-stress mortality and morbidity; Develop regional-specific correlation between increasing urban albedo and global warming; Assist local, states, and federal governments to develop regional energy codes, standards, implementation guidelines; Organize workshops and conference to disseminate information to practitioners and policy makers; and Seek and train HQP with strong background in buildings and community design, material development, climate and air quality modeling, and codes and standards development.