the effects of urban heat on human health can be significant and are likely to worsen as a result of climate change. if supported by further studies, the research results have clear policy implications, highlighting an adaptive mechanism via which humans can ameliorate the impact of climate change on urban populations.

cities are particularly vulnerable to climate change because they are warmer than rural areas. asphalt roads, tar roofs and other artificial surfaces absorb heat from the sun, creating a heat-island effect that can raise temperatures by an average 2-5 degrees fahrenheit (about 1-3 degrees celsius). white roofs reflect some of that heat back into space and thus cool temperatures–much as wearing a white shirt on a sunny day causes one to feel cooler than wearing a dark shirt.

researchers used a new computer model, designed to assess the impacts of a changing climate on urban populations and to explore options for countering rising temperatures. while the model did not capture individual cities, it did show the white roof effect in large metropolitan regions. the new york area, for example, would cool by almost 2 degrees fahrenheit on summer afternoons.

the model simulates the amount of solar radiation that urban surfaces absorb or reflect, capturing such factors as the influence of roofs, walls, streets and green spaces on local temperatures. the researchers then analyzed the interactions of global climate change and urban areas.

in this video, renowned physicist and energy efficiency expert arthur rosenfeld discusses research at lawrence berkeley national laboratory (lbnl) that for the first time quantifies the reflective power (albedo) of urban surfaces that would be necessary to mitigate the urban heat-island effect and offset carbon dioxide emissions. other speakers discuss insulated and vegetated (“green”) roofs and how different types of cool roofs may be combined or integrated with solar-roofing systems, photovoltaics (pv) and/or solar thermal technology. more information is available at bit.ly/​coolrf

in 2009, i set out to change that by launching white caps, green collars llc, a company devoted to coating flat roofs white in st. louis–a city with hot, humid summers and hundreds of thousands of flat roofs. white coatings reflect 85 to 90 percent of sunlight. that blocks heat absorption to keep homes, schools and businesses comfortably cool, dramatically reducing air conditioning usage with savings of 20 to 40 percent in hot weather months.

but the benefits for our cities and planet may be even more far-reaching. reducing electricity consumption lowers air and greenhouse gas pollution from coal-burning power plants, and u.s. energy secretary steven chu points out that because white surfaces reflect the sun’s rays back into space rather than heating our atmosphere, they offset greenhouse gas emissions through the albedo effect, too. studies have shown that cool white roofs can help reduce the urban heat island effect.

in addition to providing white roof-painting services, i’ve been a staunch advocate for their benefits and for stronger energy efficiency policies, and was named a “clean air success story” in 2010 by the st. louis regional clean air council. we donate empty, 5-gallon pails to habitat for humanity’s restore, and provide new job opportunities for graduates of st. patrick center’s “go green!” training program. white caps, green collars and several of our customers have been featured in a front-page article in the st. louis post-dispatch, on kmov-tv, in numerous articles and even a high school textbook about entrepreneurship. “green”, for me, is a roadmap for success.

see white caps, green collars on the local news:
http://www.kmov.com/video/featured-videos/go-green-white-roofs-save-money-91963704.html

watch u.s. energy secretary steven chu explain the benefits: