Effect of reflective pavements on building energy use

Optimization of building energy use in an urban area requires understanding of the complex interaction between urban morphology, materials, and climate, which can have unanticipated effects on urban microclimates and building energy use. Reflective pavements reduce urban air temperatures and have been proposed as a mitigation measure for urban heat islands. However, the increased solar reflectivity also transports more solar radiation into (through windows) and onto adjacent buildings possibly increasing building energy use. The effect of albedo changes in the urban canopy floor surface on building thermal loads is investigated using the Temperature of Urban Facets Indoor-Outdoor Building Energy Simulator (TUF-IOBES). A case study for a four storey office building with 1820 m(2) floor area and 47% window to wall ratio in Phoenix, Arizona was conducted. Increasing pavement solar reflectivity from 0.1 to 0.5 increased annual cooling loads up to 11% (33.1 kWh m(-2)). The impacts on annual heating loads and canopy air temperatures were small. The confounding impacts of canopy aspect ratio, building insulation conditions reflective of building age, and window type and size were also quantified. Policymakers should carefully weigh the benefits and local energy use implications of reflective pavements for each site to ensure their optimal application. (C) 2012 Elsevier B.V.