market, policy and end-users. In tropical Australia, zinc-galvanized (silvery) sheeting (usually corrugated) do not reflect heat as well as the truly "cool" color of white, especially as metallic surfaces fail to emit infrared back to the sky. European fashion trends are now using darker-colored aluminium roofing, to pursue consumer fashions. NYC °CoolRoofs NYC °CoolRoofs is a New York City initiative to coat rooftops white with volunteers. The program began in 2009 as part of PlaNYC, and has coated over 5 million square feet of NYC rooftops white. On Wednesday, September 25, 2013 Mayor Michael R Bloomberg declared it "NYC °CoolRoofs Day" in New York City with the coating of its 500th building and reducing the carbon footprint by over 2000 tons. Volunteers use paintbrushes and rollers to apply an acrylic, elastomeric coating to the roof membrane. A 2011 Columbia University study of roofs coated through the program found that white roofs showed an average temperature reduction of 43 degrees Fahrenheit when compared to black roofs. White Roof Project White Roof Project is a US nationwide initiative that educates and empowers individuals to coat rooftops white. The program's outreach has helped complete white roof projects in more than 20 US states and five countries, engaged thousands in volunteer projects, and sponsored the coating of hundreds of nonprofit and low-income rooftops. Urban heat island effect An urban heat island occurs where the combination of heat-absorbing infrastructure such as dark asphalt parking lots and road pavement and expanses of black rooftops, coupled with sparse vegetation, raises air temperature by higher than the temperature in the surrounding countryside. Green building programs advocate the use of cool roofing to mitigate the urban heat island effect and the resulting poorer air quality (in the form of smog) the effect causes. By reflecting sunlight, light-colored roofs minimize the temperature rise and reduce cooling energy use and smog formation. A study by LBNL showed that, if strategies to mitigate this effect, including cool roofs, were widely adopted, the Greater Toronto metropolitan area could save more than $11 million annually on energy costs. See also Blue roof Building insulation Cool pavement Green roof Insulative paint Metal roof Passive cooling Passive daytime radiative cooling Passive solar building design Passive solar design Thermal insulation Weatherization References External links Roofs Low-energy building Solar architecture Climate engineering