Introduction
In 2019, New York City introduced Local Law 97 (LL97), a building code with the goal of reducing greenhouse gas emissions (GHGs) by two-thirds by 2050. The law was part of NYC’s Climate Mobilization Act, a legislative package seeking to address the climate crisis by making the city carbon neutral within the next few decades. LL97 is a significant component of the emission reduction plan as it requires certain buildings in NYC to meet GHG emissions reduction requirements. Enforcement for emissions limits began in 2024, with stricter limits taking effect in 2030.
Buildings that are subject to LL97 include those over 25,000 square feet, two or more buildings on the same lot with over 50,000 square feet, and two or more condominium buildings under the same ownership that exceed 50,000 square feet. There are exemptions for certain city-owned, non-profit, religious, and healthcare buildings. It also does not apply to single-family homes. In total, LL97 requirements cover almost 50,000 properties across NYC. Specific carbon caps for 2024 were established with the Department of Buildings Rule 103-14. These emission caps vary across 60 property types and are determined using the EPA’s Energy Star Portfolio Manager, which sets emissions limits based on size, building type, and compliance year.
LL97 Emission Standards Timeline
The increasing stringency of building emissions limits is a critical component of LL97. Four compliance periods will be set from 2024-2050 with stricter limits on building emissions to meet net-zero carbon emissions goals. Between 2024-2029, emissions caps start off much higher than the subsequent compliance period, 2030-2034. The emission limits are approximately cut in half following each compliance period. As displayed in Figure 1, different property types have different emissions caps but ultimately seek to reach carbon neutrality by 2050.
Figure 1: Urban Green Council LL97
Goals
Buildings account for 70 percent of NYC’s emissions, making LL97 requirements a significant step toward deep decarbonization across the city. With comprehensive efforts to comply with LL97, the city expects to reduce emissions by 6 million tons of carbon dioxide. By creating emissions requirements for properties, property owners are now required to consider strategies to reduce emissions as a part of their ownership responsibilities. Moreover, the law is projected to create an increased retrofit market that may spur job development. The city projects that over 26,700 new jobs will be created by 2030 as a byproduct of compliance efforts, including retrofitting buildings, construction, and energy auditing.
LL97 works with the NY State Climate Leadership and Community Protection Act (CLCPA) to invest in renewable energy and transition the energy grid away from fossil fuels. CLCPA goals include 70 percent clean energy by 2030 and 100 percent by 2040. Ultimately, LL97 sets an ambitious target toward energy transition in NYC that attempts to align with the CLCPA.
To enhance compliance and ease the transition, the city has invested in the NYC Mayor’s Office of Climate & Environmental Justice “NYC Accelerator.” The NYC accelerator is a technical assistance program that provides a variety of resources to enhance energy efficiency and better comply with LL97. On their website, they offer information on a building’s energy use and LL97 compliance status. Guidance, training, service providers, and financing options are all available to ease the transition for property owners.
Challenges
Technical & Financial
The main challenge that LL97 presents is the financial and technical implementation of decarbonization infrastructure. A financial analysis conducted by the city has found that about 15,000 buildings would need an investment of up to $15 billion to achieve emissions targets. An early analysis of LL97 has also found that the majority of buildings that moved into compliance were advantaged communities. They found that only 39 percent of the buildings that moved into compliance were in disadvantaged community areas (DACs) as classified by the city. This demonstrates a need for the city to support compliance efforts of DACs, as they face financial difficulty investing in decarbonization infrastructure.
The real estate market is one sector that has a significant implementation challenge as developers and owners must fall into compliance. However, without direct control over the building’s energy usage, regulating emissions becomes more difficult. Seeking solutions for regulating building emissions, building owners may pass the cost of retrofits or non-compliance fees onto tenants. While building owners are the primary group responsible for such changes, it will be important for tenants to carefully review lease agreements to ensure they are not responsible for increased building operating costs. Moreover, the NYC Accelerator has provided resources for temporary assistance pathways for building owners that are experiencing outsized financial difficulty with compliance.
Legal
LL97 also faced a significant legal challenge in 2022 in the New York State Supreme Court. The lawsuit, Glen Oaks Village Owners Inc. v. City of New York, attempted to block LL97 on the basis that the NYC law was preempted by the state law, Climate Leadership and Community Protection Act (CLCPA). Preemption is a legal doctrine that explains when two laws come into conflict, the higher authority displaces the lower authority. For example, if there is a federal and state law that governs the same subject matter and they come into conflict, the federal law would preempt the state law. In this case, the NY State Court held that LL97 did not preempt the CLCPA as they were not found to be in conflict with each other.
While the initial case was dismissed, this decision was challenged and the case went through the NY Appellate Court. The NY Appellate Court is the state’s highest court and they ultimately supported the trial court’s initial decision. On May 22, 2025, the court dismissed the legal challenge and upheld LL97. With the main legal challenge behind it, LL97 expects to continue on its timeline of increasingly stringent emissions standards. The Urban Green Council has estimated that 92 percent of all required buildings have met 2024 emission limits. The next compliance period is 2030 and following the first compliance period in 2024, there have been some changes made to the penalty structure to better accommodate affordability such as a temporary timeline and emission adjustments for financially constrained owners. As building owners approach the next compliance period, there is a lot of work to be done to comply with this regulatory framework.
Conclusion
Local Law 97 represents a major municipal effort to reduce greenhouse gas emissions from buildings, which account for the majority of New York City’s emissions. The law establishes emissions limits, compliance timelines, and technical support programs, aiming to promote energy reduction and decarbonization across the city. Implementation has involved financial and technical challenges, particularly for buildings in disadvantaged communities, and the law has faced legal scrutiny. Early data indicate substantial participation among required buildings, highlighting LL97’s central role in the city’s broader climate and decarbonization initiatives.