What Is Local Law 97?
Local Law 97 (LL97) is New York City's building emissions law, enacted in 2019 as part of the Climate Mobilization Act. It sets carbon intensity limits for most buildings over 25,000 square feet, roughly 50,000 properties citywide, and assesses financial penalties on buildings that exceed those limits.
The law focuses on buildings because they account for roughly 70% of the city's greenhouse gas emissions. The limits become stricter over time, so a building's exposure generally increases in later compliance periods.
Which Buildings Are Covered?
LL97 applies to most buildings over 25,000 gross square feet in New York City, including:
- Residential buildings (condominiums, co-ops, and rentals) above the threshold
- Commercial office buildings
- Mixed-use properties
- Hotels, hospitals, and institutions
Some buildings follow different requirements. Houses of worship and certain affordable housing, including buildings with more than 35 percent rent-regulated units, follow Article 321, which requires a set of prescriptive energy conservation measures or meeting the 2030 limits. The DOB publishes an annual Covered Buildings List that confirms each building's status.
How Are LL97 Penalties Calculated?
The penalty is not a flat fee. It is based on how far a building's annual emissions exceed its limit.
Actual Emissions = Σ (Annual Energy Use × Carbon Coefficient for each fuel)
Emissions Limit = Σ (Floor Area × Emissions Intensity Limit for each occupancy type)
The emissions intensity limit is set by occupancy type, so office, residential, and retail space each carry different limits. The $268 per metric ton penalty rate is set by the law.
An Example
Consider a 100,000 square foot mixed-use building with an emissions limit of 4.53 kg CO₂e per square foot. If its actual emissions are 6.00 kg CO₂e per square foot, the overage is 1.47 kg CO₂e per square foot, or 147 metric tons for the building. At $268 per ton, the annual penalty would be $39,396.
Penalties are assessed annually. A building that remains over its limit owes a penalty for each year it is over, and the amount generally increases when the limits tighten in 2030.
Compliance Periods and the 2030 Change
LL97 is organized into compliance periods, each with stricter limits than the last:
| Period | Years | Limits | Penalty Rate |
|---|---|---|---|
| Period 1 | 2024–2029 | Most covered buildings are expected to comply | $268 per tCO₂e |
| Period 2 | 2030–2034 | Substantially stricter for most occupancy types | $268 per tCO₂e |
| Period 3 and later | 2035 onward | Continue to decline toward net zero by 2050 | $268 per tCO₂e |
Period 1 limits were set so that most buildings could comply without major retrofits. Period 2 limits, which begin January 1, 2030, are considerably lower, and many buildings that comply today would exceed them without changes.
Timing matters because major retrofits such as HVAC replacement, electrification, and envelope work often take 18 to 36 months from planning through completion. Buildings that start planning in 2028 or 2029 may have difficulty finishing work before the 2030 limits take effect.
What Drives a Building's LL97 Emissions?
LL97 emissions are calculated from energy consumption and the carbon coefficient assigned to each fuel. Three factors account for most of a building's exposure.
1. Natural Gas and Fuel Oil
Gas and oil boilers, gas-fired hot water, and similar equipment are the main source of LL97 emissions in many NYC buildings. Buildings that rely heavily on these fuels tend to have higher exposure.
2. Electricity Coefficients
LL97 assigns a carbon coefficient to grid electricity. As the grid adds cleaner generation, the coefficient for later periods is expected to decline, which tends to favor electrified systems over time.
3. Building Size
Penalties scale with building size. A 500,000 square foot building that is 10% over its limit faces five times the penalty of a 100,000 square foot building in the same position.
What Building Owners Can Do Now
The first step is to establish where the building stands. Some owners find they already comply for Period 1 but face significant exposure in Period 2. Others find they are closer to compliance than they expected.
From there, a plan typically combines several of the following:
- Operational improvements: scheduling, controls, and maintenance changes that reduce energy use with little capital cost
- Equipment upgrades: replacing aging gas- or oil-fired equipment with more efficient or electric alternatives at end of life
- Electrification: converting heating and hot water systems to heat pumps
- Renewable energy credits (RECs): a limited compliance option available under specific conditions
- Incentive programs: NYSERDA and Con Edison programs that can offset part of the cost of qualifying upgrades
The right combination depends on the building's occupancy, systems, lease structure, and financial position.
Start with the data. Our free LL97 calculator looks up a building by address and estimates its emissions, compliance status, and projected penalties for Period 1 and Period 2. No signup is required.
Reporting and Enforcement
LL97 compliance is self-reported. Building owners file annual emissions reports with the NYC Department of Buildings, and the first reports, covering 2024 emissions, were due in May 2025. Penalties for failing to file are separate from, and in addition to, penalties for exceeding the emissions limit.
The DOB enforces both requirements. Owners who have not yet filed should treat the filing as an immediate priority.
See Where Your Building Stands
Our free LL97 calculator uses NYC open data to estimate a building's emissions, compliance status, and potential penalties. No signup is required.