Looking Up: How Green Roofs and Cool Roofs Can Reduce Energy Use, Address Climate Change, and Protect Water Resources in Southern California

This report shares the results of a new study from the Natural Resources Defense Council and the Emmett Center on Climate Change and the Environment at UCLA School of Law, on the many benefits of green roofs and cool roofs for communities in southern California.   Some of those benefits are quantified, including building cooling energy savings, greenhouse gas emissions reductions, and, for green roofs, stormwater volume reduction. Policy recommendations to achieve these benefits are provided as well. 

According to the report, if green roofs or cool roofs were installed on 50 percent of existing roof surfaces for residential, commercial, and government and public use buildings in southern California, it could save up to 1.6 million megawatt hours of electricity annually, enough energy to power more than 127,000 homes in California and save residents up to $211 million in energy costs each year based on 2012 rates.  The energy savings would cut carbon pollution by 465,000 metric tons annually. Because green roofs absorb and evaporate rainfall, installing green roofs on 50 percent of the existing roof surfaces could reduce stormwater runoff by more than 36 billion gallons each year - significantly reducing the volume of pollution reaching local waters.  Additionally, green and cool roofs can cut urban temperatures, reducing temperatures in urban cores by as much as 3.5 degrees Fahrenheit, with air quality and human health benefits.

The report explains specifically how green roofs and cool roofs can help reduce impacts from climate change.   The use of energy for building cooling and mitigate the effects of the urban heat island effect, resulting in less greenhouse gas emissions that contribute to global warming and threaten the region's water supplies.  The challenges of securing an adequate, reliable water supply in the region will become exacerbated by climate change in the coming years, while stormwater runoff pollutants can be minimized by green roofs.

In conclusion, policy recommendations are outlined and specifically are to: provide incentives for residential and commercial private-party use of green roofs and cool roofs; adopt stormwater pollution control standards that require on-site volume retention;  provide guidance or other affirmative assistance for green roof and cool roof projects; adopt and implement stormwater fee and rebate programs; and to fully fund the U.S. EPA Clean Water State Revolving Fund.   

 

Publication Date: June 2012

Authors or Affiliated Users:

  • Noah Garrison
  • Cara Horowitz
  • Chris Ann Lunghino

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  • Best practice

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