A paint that reduces surface temperature

An innovation that fits under the category of trying to cope with the hotter weather brought on by climate change …

A team from the University of Colorado “has developed a passive radiative cooling plastic film.”  This new material, applied as paint to an existing outdoor surface, “could drop cooling costs by up to 15% in some climates.”  Air conditioning accounts for some 17% of all residential electricity use in the United States; using this film to reduce surface temperatures and lessening the need for air conditioning could mean substantial savings.

This innovation builds on the long-standing practice of painting homes white in tropical countries–the white color reflecting “as much sunlight as possible.”  But, normal white paint “typically reflects … about 80% of visible light” plus it still absorbs ultraviolet and near-infrared light–all of which warms buildings.

The new materials “reflect nearly all the sun’s incoming rays” and also deal with near-infrared and ultraviolet light as well (up to 99.6% overall).  The materials reflect the heat “without warming the surrounding air.”

Multiple research teams around the world are working on passive radiative cooling materials.  The efforts include a “polymer and silver film combo to cool water for use in air conditioning,” this plastic film/paint (embedded with tiny glass beads), and a polymer roofing material.  Each has been shown to cool surfaces by as much as 10 degrees C and save cooling costs.

The new cooling paint appears to solve an additional challenge as well–applying these new materials to existing buildings.  The paint has been successfully tested in the heat of Phoenix, Arizona where “painted surfaces remained 6 degrees C cooler than the surrounding air.”

Read the article (Robert F. Service, Science, September 27, 2018).

For more information about the impacts of climate change and attempts to adapt and mitigate, search the Science Primary Literature Database and the Headline Science Database.

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