New York City Local Law 21

Introduced in 2011 by Council Member Garodnick, Brewer, Chin, Comrie, Fidler, Gentile, Gonzalez, James, Koppell, Lander, Mark-Viverito, Nelson, Palma, Sanders Jr., Vann, Williams, Rodriguez, Gennaro, Van Bramer, Levin, Lappin, Recchia, Vallone, Crowley, Jackson, Koo, Wills, Barron and Greenfield

To amend the administrative code of the city of New York and the New York city building code, in relation to roof coating standards

Be it enacted by the Council as follows:

Section 1. Legislative findings and intent. The Council finds that the use of cool roofs as a mitigation strategy for the “urban heat island effect”-- the tendency of urban areas to be hotter than their suburban surroundings because of dark absorbent surfaces and a lack of vegetation--can result in lower energy use and reduced air pollution and greenhouse gas emissions, while at the same time improving health and comfort in warm weather. A cool roof transfers less heat to the building below so that the building stays cooler and more comfortable during the summer, resulting in the use of less energy for cooling. A cool roof coating also increases the durability of the roof membrane because it is subject to reduced thermal cycling amplitude and UV radiation. At the same time local climate and site specific factors play a role in the amount of savings achieved. Cool roofs result in energy savings when they are most needed, during very hot summer periods subject to peak electrical demand. The disadvantages over the heating season, known as the “winter penalty”, have been found to be minimal in studies of New York City’s installations. The Council further finds that studies show that North Atlantic states with relatively long heating seasons may nonetheless benefit and reap net savings from cool roofs because of high electricity costs in places like New York City. On a global level, implementing the proposal will also help combat global warming, because light is reflected into space rather than being turned into heat, which is then trapped in the CO2 blanket.

Further, to the extent that energy demand is lessened, it can result in fewer air emissions and air quality related environmental diseases. New York City began addressing these issues by incorporating a requirement for white roofs in its last code cycle. Therefore, the Council finds that it is in the best interests of New York City to strengthen its roof coating standards to require the use of more reflective and emissive materials. Read more