Over the past year, more than 1,500 volunteers have applied white, reflective coatings to 1 million square feet of New York City rooftops to help reduce cooling costs, energy usage and greenhouse gas emissions.
The NYC °CoolRoofs program is a collaboration with NYC Service–an initiative launced by Mayor Michael Bloomberg to target more volunteers towards areas of need.
The program will help the City’s efforts to reduce greenhouse gas emissions by 30% by 2030, a primary goal of PlaNYC, the City’s comprehensive sustainability plan.
“Through NYC Service we are tapping into the incredible spirit of volunteerism in our city and harnessing that energy to tackle some of the challenges government can’t solve on its own and that includes reducing the city’s carbon footprint,” said Mayor Bloomberg. “By simply applying a reflective, white coating, we can reduce rooftop temperature by up to 60 degrees, which translates into reduced cooling costs and reduced carbon emissions.”
Under the NYC °CoolRoofs Program, the roofs of 105 of public, private and non-profit buildings received reflective white coating. This includes more than 340,000 square feet of City-owned rooftops, which were identified by the Department of Citywide Administrative Services, and 70,000 square feet of rooftop on NYCHA facilities.
The full program began in May 2010, with 900,000 square feet of rooftop coated in only five months. During initial pilot program, which ran in the fall of 2009, 100,000 square feet of rooftop was coated. The program does not operate during winter months.
In 2011, NYC Service will make its volunteers available for roof coatings to for-profit organizations that are willing to provide energy bills to the City for the purpose of culling data to further examine the impact of white rooftops.
The NYC °CoolRoofs Program is a public-private partnership that engaged 17 companies in providing volunteers and resources to coat rooftops. Con Edison (NYSE: ED), this year’s lead sponsor, was responsible for coating more than 100,000 square feet of rooftop throughout the City, including 90,000 square feet of Con Edison owned buildings.
A roof with reflective, white coating–know as a cool roof–absorbs 80% less heat than traditional dark colored roofs and can lower roof temperatures by up to 60 degrees and indoor temperatures by 10 to 20 degrees on hot days. The decrease in temperature reduces the need for air conditioning, lowering electric bills and reducing energy consumption. Coating all eligible dark rooftops in New York City could result in up to a 1 degree reduction of the ambient air temperature–a significant and lasting change towards cooling the City. The decrease in energy usage from cool roofs also will help reduce the likelihood of blackouts and brownouts, as the strain on the power grid during times of peak demand will be lessened.
Financial savings from converting to a cool roof will vary from building to building, but a self-applied coating–with no labor costs–typically pays for itself after three years through energy savings. A cool roof can reduce air conditioning costs by up to 50% in a one story building, 25% in a two story building, and up to 10% in a five story building. Further, cool roofs can extend the life of a roof by five to ten years by reducing the stress caused by extreme heat.
New York City is heavily impacted by the “urban heat island” effect–the phenomenon of cities being warmer than surrounding suburban and rural areas due to the abundance of dry, impermeable surfaces, such as roads and buildings. The urban heat island effect causes New York City to be five to seven degrees warmer than surrounding areas.
Areas of the City that are most impacted by the urban heat island effect have an abundance of industrial roofs, roadways, and a lack of vegetation. For example, the combined surface temperature in the South Bronx is approximately five to ten degrees higher on hot days than the citywide mean, according to satellite imagery.