By Steven Cohen, Ph.D., Director of the M.S. in Sustainability Management program, School of Professional Studies
The transition to a sustainable city is underway here in New York City. It will be a long road, but the path we are set on will succeed. I know that there are headwinds and obstacles. Even without the idiocy emanating out of our nation’s capital, the conversion of this city of old fossil-fuel dependent buildings to one relying on renewable resources was never going to be quick or easy. We have some advantages in that we are already the most energy-efficient city in the United States. In the rest of the country, transportation is the largest source of greenhouse gas emissions. Due to our extensive system of mass transit, most of our greenhouse gas emissions come from buildings rather than cars.
In May 2019, the New York City Council enacted Local Law 97, which requires buildings over 25,000 square feet to reduce building greenhouse gas emissions by 40% by 2030 and by 80% by 2050, with a baseline set in 2005. The law provides alternatives for some affordable housing units and houses of worship to adhere to a lower-cost pathway focused on low-cost energy efficiency measures instead of rigid carbon caps. During the first phase of implementation, from 2024 to 2029, landlords can avoid penalties by demonstrating “good faith efforts” to pursue decarbonization. All of this makes sense in a place as complicated as New York and with goals such as increasing housing affordability and reducing homelessness at least as important as decarbonization.
Despite some resistance and worry about costs, it is clear that New York City’s building owners and developers see the future and are interested in meeting the decarbonization goals to the extent they can. They also see that a more efficient and renewable resource-based energy system will, in the long run, reduce the cost of operating a building. In January 2025, Matthew Issacs, vice president of business development at Kelvin, a climate tech company focused on decarbonizing legacy radiator-heated buildings, wrote an Op-Ed in Crain’s New York Business that stated:
“The law's first year of implementation in 2024 has placed significant pressure on building owners to take meaningful steps in addressing emissions and improving reporting practices… LL97 has sparked crucial conversations among property owners, government agencies, and sustainability advocates about what it will take to collectively tackle decarbonization. However, this observation year has revealed significant challenges that could undermine the law’s success—burdensome compliance costs, vague rulemaking, and inconsistent emissions data are all hurdles that require urgent attention and refinement. When LL97 came into being it was understood the costs to modernize New York City’s buildings would be astronomical. Yet, over the past five years companies like BlocPower, Kelvin, Parity, and Runwise have pioneered financing mechanisms tied to future energy savings that can eliminate upfront costs and create an economically viable path to compliance, paid for through energy savings. These solutions show that compliance doesn’t have to be prohibitively expensive, but there is still a major need for additional financing solutions.”
In other words, decarbonization can be seen as a form of building modernization. It partially depends on the electric grid becoming decarbonized, or on the type of technological advances in solar arrays and batteries that might someday allow buildings to disconnect from the grid, in much the same way people have been disconnecting from cable TV and the wired internet. Even without new technology, there are a variety of measures that buildings can take to reduce greenhouse gas emissions by improving energy efficiency. Upgrading insulation and sealing air leaks around windows or upgrading from single-pane to multi-pane windows are reasonably low-cost options. In large buildings, heating, ventilation, and air conditioning (HVAC) systems can be modernized with higher efficiency components, automated controls, and improved maintenance to save energy. Installing LED lighting and replacing heating and hot water systems with electric heat pumps are methods of using off-the-shelf technologies that can save huge amounts of energy. Timers and sensors can also be installed to ensure that lights are turned off when no one is around.
There is political opposition to Local Law 97. The Real Estate Board of New York continues to lobby for weakening the law. Some landlords have said they’ll pay the fines since they will be less costly than the mandated changes. Co-op Boards in the outer boroughs are concerned about the cost of compliance. Andrew Cuomo, during his failed campaign for New York mayor, expressed reservations about the law, but he was defeated by Zohran Mamdani, who is a strong supporter of decarbonization. Since the Mayor-elect also ran his campaign on the theme of housing affordability, he will likely want to ensure that public subsidies are available to reduce the costs of decarbonization for those who cannot afford to pay those costs. Writing in New York Focus, just after election day this past November, Colin Kinniburgh reported that:
“Mamdani says he wants to help middle-income co-op and condo owners come into compliance with the law by lobbying Albany to extend a tax break that helps pay for building renovations, and reducing the fees to apply. He wants to staff up the city office in charge of walking building owners through the necessary upgrades. And he suggested in a recent debate that the city could provide affordable heat pumps directly to residents, building on a model the public housing authority has already tested, with promising results.”
With her reelection race for Governor already underway, we can expect Kathy Hochul to do some Cuomo-like bobbing and weaving on Local Law 97. We saw her do this with congestion pricing, first by delaying it and then, recently, deciding against temporarily raising the fee to reduce traffic on gridlock alert days. Still, as time goes on, Local Law 97 will become institutionalized, and while exceptions will increase, once landlords and developers have invested in energy modernization, they will oppose competitors avoiding compliance and beating them on costs in the marketplace. We can also expect tenants and condo customers to ask about decarbonization efforts. Some will be concerned because of their commitment to reducing greenhouse gas pollution, and others will want to know if the costs are already factored into their housing costs.
Dating back almost twenty years ago, with Mike Bloomberg’s pathbreaking sustainability PlaNYC 2030, New York City has been moving toward the goal of becoming a sustainable city. Hurricane Sandy convinced us of the importance of adapting to climate change. Billions of dollars have been spent on climate resiliency. Shorelines have been reinforced, tunnels have been made flood resistant, power plants and large buildings have made massive investments to reduce the impact of extreme weather. We’ve built bike lanes, given streets like those around Times Square to people rather than vehicles. Our mass transit and ferry system brings most New Yorkers to work each day. According to Dave Colon of StreetsBlog NYC:
“Since 2021, riderships across all modes that the MTA offers has steadily risen from 100 million rides per month to over 150 million rides per month, for a total of 6 million rides per day across the system. Most of that ridership is concentrated on the subway, where weekday ridership averaged 4 million rides per day in March for the first time since 2019.”
We’ve promoted bike sharing (about 100,000 Citi Bike rides per day), and according to the NYC Department of Transportation, over 120,000 New Yorkers commute by bike each day, and there are over 600,000 bike trips daily in New York City.
New York City has incentivized energy efficiency, implemented congestion pricing, and made residential organic waste recycling mandatory. We’ve completed a third water tunnel and started the process of institutionalizing building decarbonization. We are slowly modernizing this great city and moving it toward becoming the sustainable city it must become to maintain its unique status as the world’s true capital city. Over 60 million tourists come to New York City each year. A time traveler from fifty years ago would not recognize the place. And in a few decades, today’s New York will barely resemble the sustainable city of 2050.
Views and opinions expressed here are those of the authors, and do not necessarily reflect the official position of Columbia School of Professional Studies or Columbia University.
About the Program
The Columbia University M.S. in Sustainability Management program offered by the School of Professional Studies in partnership with the Climate School provides students cutting-edge policy and management tools they can use to help public and private organizations and governments address environmental impacts and risks, pollution control, and remediation to achieve sustainability. The program is customized for working professionals and is offered as both a full- and part-time course of study.
