Cool Roofs: A Cheap Way to Improve Energy Efficiency
Cool roofs reflect solar heat and emit absorbed radiation. In this way, they reduce the amount of solar heat transmitted to the building, helping to keep the building cool.
Cool roofs are relatively cheap to install and can significantly reduce the cooling load for areas beneath the roof. The cooling energy savings associated with cool roofs are in the order of 20% .
Cool roofs can also prolong the life of roofing materials and help to reduce urban heat island effects.
Cool roofs need not be white – there are many cool-colour pigments that reflect energy in the near infra-red range of the solar spectrum. Green roofs use plants as a roof covering – though not reflective, they provide similar cost savings as cool roofs.
In general, in areas where winter heating is not required, cool roofs provide cost savings. As such, they should be strongly considered for buildings in Rio de Janeiro.
Types of Cool Roof
Cool roofs for commercial and industrial buildings generally fall into one of three categories:
- Roofs made from inherently cool materials such as white vinyl
- Roofs coated with a solar reflective material
- Green roofs, which use plants and growth substrate as a roof covering and where cooling occurs by evapotranspiration
Cool Roof Resources
- US Dept. of Energy Cool Roof Calculator
- US Environmental Protection Agency Cool Roof Calculator
- Cool Roofs Europe
- Cool Roof Rating Council: This US based organisation administers a product rating program in which roofing manufacturers can label various roof surface products.
- Heat Island Group: The Heat Island Group at Lawrence Berkeley National Laboratory works to cool buildings, cities, and the planet by making roofs, pavements, and cars cooler in the sun.
- “Cool Roofs : City of Melbourne Research Report,” 2011. [Online]. Available: http://www.melbourne.vic.gov.au/Sustainability/CouncilActions/Documents/Cool_Roofs_Report.pdf. [Accessed: 08-Nov-2012].