Global Cooling in Action

A balloon-borne sounding system gauges thermodynamic conditions at ground level. An ISRO aircraft takes similar measurements from 7-8 km altitude. (Image courtesy of Heat Island Group, Lawrence Berkeley National Laboratory)
A satellite takes readings from rooftop instruments. The satellite's footprint ranges from 1 m to 1 km. (Image courtesy of Heat Island Group, Lawrence Berkeley National Laboratory)

Cool roofs can help to delay climate change by keeping the atmosphere cooler. Akbari et al. (2009) estimate the benefits from increased reflectance of solar radiation by all urban surfaces worldwide would amount to approximately 44 gigatonnes of CO2 offset (for the lifetime of roofs). Until now, however, such projections have not been tested in an experimental setting.

Our Global Cooling in Action project, sponsored by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) and Office of Science, seeks to experimentally verify the radiative benefits of reflective cool roofs.

Our controlled study at two sites in India will:

  • experimentally verify the radiative benefit of cool roof treatment of buildings under varying atmospheric conditions using rooftop and satellite retrieved data
  • use the field study data to verify the performance of a regional climate model that includes an urban canopy
  • evaluate heat flux and temperature changes in rooms below the treated and untreated roofs

We will be modeling simulations to capture the resulting impacts from different types of rooftops. From these simulations, we aim to inform future policy by:

  • quantifying benefits for a range of representative climatologies
  • informing future studies that might attempt to quantify the urban heat island effects in U.S. cities
  • providing essential information for analysis of future building code policies
  • helping develop urban landscape and community policies


Marc Fischer
(510) 486-5539