Beyond Roofing Basics: Sustainable Roofs and Local Law 92/94
By Ula Bochinska
A roof can be so much more than simply a barrier defending against the elements. It can house mechanical equipment or recreational space. It can also assist in making the building more sustainable, by means of cool roofs, green roofs and solar panels. In certain instances, roofs are in fact required to either incorporate a green roof or solar panels, for example in New York City, as mandated by Local Laws 92 and 94 of 2019. New York City, like other cities in the United States, is expanding on its sustainability efforts.
The OneNYC 2050 strategy was created to confront the climate crisis along with achieving equity, strengthening democracy, and other objectives. The “Livable Climate” goal is meant to achieve carbon neutrality and end reliance on the fossil fuel economy. The NYC Department of Buildings takes up this challenge by mandating that building owners install either a solar system or a green roof on top of any new roofs. The requirements apply to new buildings as well as enlargements and even installations of a new roofing system. New roofs are required to be covered 100% with solar panels, a green roof or a combination of both.
Solar panels derive electricity from solar energy, helping to shift from fossil-fuel to renewable sources. Green roofs, on the other hand, support sustainability efforts by enhancing storm water management, decreasing flooding and sewage run-off, and reducing effects of the “urban island effect” — also known as “heat island effect”. In essence, green roofs have an additional component as compared to regular roofs: they contain a layer of soil varying from several inches to several feet thick. Vegetation is then planted in the soil, and both the soil and plants retain water that would otherwise contribute to the already overloaded city storm and sewer system. Green roofs are also considered cool, as they do not heat up like your typical black top roofing membrane.
While installing a green roof or solar panels is more costly and more complex than installing a basic roofing membrane, the benefits to the building owner and the environment are grand. One should keep in mind that green roofs and solar panels add weight to the roof and therefore will require a more robust structure than a regular roof that is only required to sustain snow loads. Depending on the type of green roof, there will also be some additional steps in terms of installation and maintenance. Solar panels need to be securely fastened to the structure as they have to be able to resist strong uplift forces from wind.
As with many building code requirements, there are exemptions from the 100% sustainable roof directive. Areas of clearances required by zoning or the fire department do not need to comply with the law, neither do areas of rooftop equipment or other structures and associated required clearances. Recreational roof decks serving the building residents are also exempt. Although it appears that there are many instances where the sustainable roof rules can be averted, local governments encourage building owners to take advantage of the benefits sustainable roof features offer. For example, New York State offers real estate tax abatement programs for a financial incentive.
In the end, solar panels produce electricity that will lower or eliminate the building’s energy bills, and green roofs save on heating and cooling bills and create beautiful ecosystems for insects and humans. Both green roofs and solar panels can be combined with recreational areas for a sustainable, beautiful and relaxing environment.
We encourage owners of new or existing real estate to explore the options for sustainable roofs with a seasoned design professional, whether local laws mandate sustainable roof installation or not. Long term benefits will most likely outweigh upfront costs.
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