As New York City's Local Law 97 (LL97) deadline fast approaches, building owners wonder how the city calculates its ambitious targets for reducing greenhouse gas emissions (GHG) from large buildings. The law requires buildings over 25,000 square feet to meet strict emissions limits to reduce citywide carbon emissions by 40% by 2030 and net zero by 2050. But how exactly does NYC calculate a building's emissions profile? Let's break it down.
Calculating Building Emissions
There is a difference between calculating your building’s GHG emissions limit vs. its annual GHG emissions. The emissions limit is by property type, while the annual emissions are by fuel type. According to Nearby Engineers, NYC calculates the emissions profile of a building under LL97 by multiplying the building's annual energy consumption for each fuel type by its corresponding carbon coefficient. Here’s how it works:
- Energy Usage: Data on the building’s energy consumption for each fuel type (e.g., electricity, natural gas, fuel oil) is measured.
- Carbon Coefficients: Each fuel type has a specific "carbon coefficient" representing its carbon content.
- Emissions Calculation: The total annual energy use for each fuel type is multiplied by its corresponding carbon coefficient.
- Total Emissions: The results from the emissions calculation are summed up to determine the building's annual emissions.
Although several steps go into calculating your building’s annual emissions, there is one that is directly used to calculate your building’s emissions limit. On page 10 of NYC.gov’s “Requirements for Reporting Annual Greenhouse Gas Emissions for Covered Buildings,” it states: “Gross floor area. The owner must calculate and report the gross floor area of a covered building, and the floor area of each occupancy group or property type in a covered building. The floor area of each occupancy group or property type reported must add up to the covered building’s gross floor area.” Essentially, you break down each property type by gross floor area and multiply it by that emission factor.
To determine how to calculate buildings with single vs. multiple occupancy groups, read more here.
Emissions Limits and Compliance
Each building has an annual emissions limit that varies based on its use/property type and size. Buildings that exceed their emissions limits will face fines. With the compliance report submission deadline approaching (May 1, 2025), the fine will be $268 for every metric ton of CO2 equivalent (tCO2e) that exceeds the building's limit.
The calculation of the penalty for non-compliance looks like this:
(Annual GHG Emissions – GHG Emissions Limit) tCO2e x $268/tCO2e
Factors Affecting Emissions Profiles
According to NYC Buildings and its LL97 Compliance Report Submission Process document, “once entered into [the Building Energy Analysis Manager], BEAM will automatically calculate a building’s emissions limit using emissions factors from the current compliance period (CY2024 – 2029).” As you transition to decarbonization, here are a few things to keep in mind:
- Energy Efficiency: More efficient buildings generally have lower emissions.
- Fuel Mix: The types of energy sources used for your building impact the overall emissions.
- Building Use: Different property types have varying emissions intensity limits.
- Grid Decarbonization: As the electricity grid becomes cleaner, building emissions from electricity use will decrease.
Property owners and managers can better strategize to reduce their carbon footprint and avoid penalties under LL97 by understanding how NYC calculates building emissions. Partner with Catalyst Power today to develop the best energy strategy for your business.
