New York City Mandates Green Roof Systems for New Buildings, Major Alterations

By Frank Fortino

As we’ve covered in previous articles, New York’s Green New Deal is ushering in a host of changes for the New York City real estate industry. Officially known as the Climate Mobilization Act, the legislation includes Local Law 94 of 2019, which requires installation of a sustainable roofing zone in new construction—both residential and commercial—and for buildings undergoing certain major alterations.

Local Law 94 of 2019 Requirements

The law defines a “sustainable roofing zone” as “areas of a roof assembly where a solar photovoltaic electricity generating system, a green roof system, or a combination thereof, is installed.” Both new construction and properties that are undergoing replacement of the entire roof deck or roof assembly are required to install a sustainable roofing zone on 100% of the roof.

  • In such zones, contiguous areas measuring less than 200 ft2 must also include a solar photovoltaic electricity generating system, provided the system would generate at least 4kW of solar power, as determined by the Department of Buildings (DOB).
  • A sustainable roofing zone with a slope of 17% or less that would accommodate a solar photovoltaic electricity generating system that produces less than 4kW, as determined by DOB, shall require at least a green roof system.

Solar photovoltaic panels and modules installed on roofs or as an integral part of roof assemblies must comply with both the New York City Construction Codes and the New York City Fire Code.


The legislation includes the following exceptions:

  • Areas required to be reserved for setbacks or access, according to the New York City Fire Code, the New York City Construction Codes, or the Zoning Resolution of the City of New York
  • Areas occupied by rooftop structures, mechanical equipment, towers, solar thermal systems, parapets, and accessories.
  • Areas occupied by obstructions related to stormwater management, such as cisterns or reuse systems installed for Department of Environmental Protection compliance
  • Terraces on setbacks that occupy less than 25% of the building’s largest floor plate area
  • Recreational spaces that are integral to the use of the building
  • A roof assembly with a slope greater than 17% that would accommodate less than 4kW of solar electricity generating capacity
  • Areas where DOB determines that site conditions are unfavorable to either a solar photovoltaic electricity generating system or a green roof system

To discuss how this legislation will affect your projects, please contact Metropolis Group at 212.233.6344.