BE-Ex Climate Mobilization Act Series: Solar & Green Roofs

BE-Ex Climate Mobilization Act Series: Solar & Green Roofs

Gotham 360 attended an event hosted by the Building Energy Exchange focused on Local Laws 92 and 94, that require solar and/or green roofs for all new constructions and major roof renovations. The laws were passed as a part of the Climate Mobilization Act (CMA). Thanks to these laws, NYC may now have the most sustainable roofing policy in the world.

The event had speakers from the NYC Mayor’s Office of Sustainability, Thornton Tomasetti, Solar One, and Fisher and Partners.

Local Laws 92 and 94 seek to convert the currently underutilized assets of city rooftops into areas that can clean the air, reduce stormwater runoff and flooding, generate electricity, and provide green spaces for building occupants. Buildings account for two-thirds of NYC’s greenhouse gas emissions, so there is a huge opportunity to reduce their impact. Compliance will begin on November 19, 2019.

These local laws have huge impacts for the city. It is estimated that 35 MW of new solar capacity will be added annually, which is equivalent to taking 9,000 households off the grid. Over 1 million tons of greenhouse gas emissions will be reduced by 2030. More than 800 jobs will be created annually. Up to 1 million additional gallons of stormwater will be managed each year, and millions of square feet of cool roofs will be added annually.

The new laws apply to all new construction, vertical and horizontal extensions, and major roof renovations. Buildings must cover all available and usable roof area in solar and/or green roofs. Buildings must install green roofs if solar is not feasible, and vice versa. If possible, integrated solutions with both solar and green roofs are ideal and optimize benefits.

The laws are flexible, allowing property owners to choose what is most cost-effective for their property. A series of exceptions exist for the laws. If a building cannot accommodate at least 4 kW of solar capacity or 200 square feet of green roof, it is eligible for an exception. Likewise, for low-rise residential buildings, the exemption threshold is 100 square feet. Affordable housing is provided with an alternative compliance pathway.

These laws are an excellent step forward for making the NYC skyline more sustainable. Green roofs can mitigate pollution from sewer overflows and hazardous urban flooding. They double the lifespan of roofs and reduce heating and cooling costs. Lastly, they provide New Yorkers with green space that is easily accessible and wildlife with additional habitats. Increasing solar capacity in NYC has many benefits as well, including reducing energy costs, especially when paired with a green or cool roof. They deliver strong financial returns, with payback periods often in the 5 to 10 year range. They also help get NYC closer to the city-wide goal of 250 MW of solar by 2025 and 1,000 MW by 2030.


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