When I think of a cool roof, I usually picture a green roof covered with vegetation. But another popular method to cool a roof is to coat it white with a light-colored, reflective paint.
I volunteered to install an extensive green roof at 594 Broadway of sedums, seeds, and cuttings in September 2010. This spring, I watched the installation of a NYC °CoolRoof on 154th Street. (It was my intention to help to paint the roof but an injury prevented me from doing so.)
NYC °CoolRoofs was initiated three years ago as one of numerous strategies to reduce the city's greenhouse gas emissions by 30% by 2030. Learn more about the city's sustainability master plan or PlaNYC here. Cool roofs offer several benefits. Coating a roof with a light colored material or paint reduces roof temperatures, internal building temperatures, carbon emissions and the urban heat island effect. The impact of cooler internal temperatures is most acute for the top floors of a building. Cooler air and surface temperatures reduce the demand for air conditioning thus limiting emissions and improving air quality. Two added benefits are longer lasting roofs and cooling equipment.
NYC °CoolRoofs has developed a self-reporting tool for building owners who coat their roof without assistance from the program. °CoolRoofs relies on volunteers to lower the cost for nonprofit and other financially-eligible property owners. Yale Day of Service volunteers coated the roof of Macombs Manor at 254 West 154th Street, a Harlem Congregations for Community Improvement (HCCI) residential property in May 2012. HCCI owns 2,000 housing units and 40 commercial sites. The total roof area at Macombs is 9,000 square feet but only 4,500 square feet were slated for coating on the May work day. Nine volunteers and a few °CoolRoofs staff applied the first coat of latex to the roof's flashing by noon. The completed cool roof lowers residents' utility bills and creates a safer and more comfortable living environment.
New State offers incentives to residential and commercial properties to install a cool roof. Review the °Cool It Yourself guide to determine if your roof is eligible for a cool roof coating.
P.S. Have you heard of a blue roof? Blue roofs are designed to detain stormwater without the use of vegetation. The NYC Dept. of Environmental Protection is testing the efficacy of conventional, green, and blue roofs to manage stormwater at PS 118 in Queens. The DEP website notes that a blue roof outfitted with light-colored material "can provide sustainability benefits through rooftop cooling."