 
Local Law 97 Emission Factors Explained (Electricity vs Gas vs Steam)
Introduction
For many New York City building owners, Local Law 97 (LL97) has shifted the conversation from energy consumption to carbon emissions. Two buildings may use the same amount of energy, yet one could produce significantly more greenhouse gas emissions than the other. The difference often comes down to emission factors.
Understanding Local Law 97 emission factors is essential because they determine how your building’s electricity, natural gas, and district steam usage translates into carbon emissions. These values directly affect whether your property stays below its assigned emissions limit or faces financial penalties.
Whether you manage a commercial office, multifamily property, healthcare facility, university building, or mixed-use development, knowing how emission factors work can help you make smarter operational and capital investment decisions.
This guide explains the differences between electricity, natural gas, and steam emission factors, how they influence LL97 compliance, and what building owners can do to reduce carbon emissions while preparing for future compliance periods.
What Are Local Law 97 Emission Factors?
An emission factor is a standardized value used to convert energy consumption into greenhouse gas emissions.
Under Local Law 97, every fuel source has a different carbon intensity. Instead of measuring only how much energy a building consumes, the law measures the total greenhouse gas emissions produced from that energy.
The calculation is straightforward:
Building Energy Consumption × Emission Factor = Annual Carbon Emissions
For example, consuming 100,000 kWh of electricity does not automatically indicate whether a building is compliant. The electricity usage must first be multiplied by the applicable electricity emission factor established under Local Law 97.
This approach creates a more accurate representation of a building’s environmental impact rather than focusing only on energy efficiency.
Why Emission Factors Matter for LL97 Compliance
Many property owners assume lowering utility bills automatically improves compliance. While energy efficiency is important, carbon intensity is equally important.
Different energy sources produce different amounts of greenhouse gases.
For example:
- Electricity has one emission factor.
- Natural gas has another.
- District steam uses a completely different calculation.
- Fuel oil has its own carbon value.
Because of these differences, replacing one fuel source with another can significantly change a building’s annual emissions—even if overall energy use remains similar.
This is why Local Law 97 encourages building electrification, cleaner heating systems, and investments in renewable electricity over time.
Understanding Electricity Emission Factors
Electricity is unique because buildings do not directly produce emissions when using it. Instead, emissions occur where electricity is generated.
The electricity emission factor reflects the average greenhouse gas emissions associated with producing power supplied to New York City’s electrical grid.
As New York increases renewable energy generation through solar, offshore wind, hydroelectric power, and other clean energy sources, the carbon intensity of electricity is expected to decrease over time.
This means buildings that transition from fossil fuel systems to efficient electric equipment may benefit from lower emissions in future compliance periods.
Examples of electric systems include:
- Heat pumps
- Electric domestic hot water systems
- Electric cooking equipment
- Variable refrigerant flow (VRF) systems
- Electric boilers in certain applications
However, electrification alone does not guarantee compliance. Building efficiency still plays an important role because excessive electricity consumption can still result in higher emissions.
How Natural Gas Emission Factors Work
Natural gas remains one of the most common heating fuels in New York City buildings.
Unlike electricity, burning natural gas creates direct on-site greenhouse gas emissions. Every therm of gas consumed contributes directly to a building’s annual carbon footprint.
Natural gas emission factors account for:
- Carbon dioxide released during combustion
- Greenhouse gas intensity of the fuel
- Standardized emissions calculations required by Local Law 97
Buildings that rely heavily on gas-fired boilers, water heaters, or heating systems often face greater compliance challenges, particularly as future LL97 emissions limits become more stringent.
While high-efficiency gas equipment can reduce fuel consumption, it cannot eliminate combustion-related emissions.
District Steam Emission Factors Explained
Many large commercial buildings in Manhattan use district steam for heating.
District steam is generated at centralized facilities before being distributed through underground piping to connected buildings.
Although building owners do not burn fuel on-site, emissions are still associated with producing the steam. Therefore, Local Law 97 assigns an emission factor to steam consumption.
Steam emission factors consider:
- Fuel used to generate steam
- Production efficiency
- Distribution losses
- Greenhouse gas emissions from centralized generation
Buildings using district steam often have different compliance strategies compared to buildings using gas-fired boilers because they have less direct control over steam production.
Nevertheless, improving building efficiency still lowers steam consumption and associated emissions.
Electricity vs Gas vs Steam: Which Produces Lower Emissions?
There is no universal answer because emissions depend on several variables, including building operations, equipment efficiency, occupancy, and future grid improvements.
In general:
| Energy Source | Emission Characteristics | Compliance Considerations |
| Electricity | Indirect emissions from the power grid | Expected to become cleaner as renewable energy increases |
| Natural Gas | Direct combustion emissions | May become more difficult to maintain under future LL97 limits |
| District Steam | Centralized production emissions | Efficiency improvements can reduce overall emissions |
For many buildings, the long-term trend favors cleaner electricity as New York expands renewable energy generation.
However, every property requires its own engineering analysis before making major equipment upgrades.
How Emission Factors Affect Building Planning
Emission factors influence much more than annual reporting.
They affect decisions involving:
HVAC modernization
Replacing aging heating equipment with high-efficiency electric systems may lower future emissions.
Capital improvement planning
Building owners often prioritize projects based on expected carbon reductions instead of only energy savings.
Financial forecasting
Lower emissions may reduce future Local Law 97 penalties while improving long-term operating costs.
Sustainability reporting
Accurate emissions calculations support ESG reporting, investor requirements, and corporate sustainability goals.
Common Mistakes Building Owners Make
Many owners misunderstand how emission factors work.
Some of the most common mistakes include:
Assuming all energy sources have equal environmental impact
One unit of electricity does not produce the same emissions as one unit of natural gas or steam.
Focusing only on utility costs
Lower utility bills do not always translate into lower greenhouse gas emissions.
Waiting until compliance deadlines
Major equipment replacements require planning, budgeting, permitting, and installation.
Ignoring future compliance periods
Emission limits become stricter after the initial compliance period, making long-term planning increasingly important.
Using outdated assumptions
Local Law 97 guidance continues to evolve, and buildings should rely on current regulations and professional analysis.
Strategies to Reduce Local Law 97 Emissions
Reducing emissions usually requires a combination of operational improvements and capital upgrades.
Effective strategies include:
Improve building efficiency
Reduce unnecessary energy consumption through:
- Lighting upgrades
- Occupancy controls
- Building automation
- HVAC optimization
- Preventive maintenance
Electrify where practical
Replacing fossil fuel equipment with efficient electric alternatives may improve future carbon performance.
Optimize heating systems
Boiler tuning, temperature resets, and improved controls can reduce fuel consumption.
Upgrade building envelope
Better insulation, windows, and air sealing reduce heating and cooling demand.
Monitor energy continuously
Ongoing energy monitoring helps identify operational issues before they increase annual emissions.
Why Professional Carbon Analysis Matters
Every building has unique operating characteristics.
A property using large amounts of electricity may still perform better than a gas-heated building depending on equipment efficiency, occupancy patterns, and overall energy use.
Professional Local Law 97 consultants evaluate:
- Utility consumption
- Fuel mix
- Carbon emissions
- Future compliance risks
- Capital improvement opportunities
- Financial impacts of potential penalties
This analysis helps owners prioritize projects that deliver the greatest carbon reductions with the strongest return on investment.
Frequently Asked Questions
What are Local Law 97 emission factors?
They are standardized values used to convert electricity, natural gas, steam, and other fuel consumption into annual greenhouse gas emissions for compliance calculations.
Does electricity always produce fewer emissions than natural gas?
Not necessarily. Electricity generally becomes cleaner as the power grid incorporates more renewable energy, but actual emissions depend on consumption levels and the applicable emission factor.
Why does district steam have an emission factor?
Although buildings do not generate steam themselves, emissions occur during centralized steam production, so Local Law 97 assigns a carbon value to steam consumption.
Can switching from gas to electricity improve LL97 compliance?
In many cases, electrification can reduce future emissions, especially as New York’s electric grid becomes less carbon intensive. However, each building should undergo a detailed engineering and financial analysis before making major changes.
How can building owners prepare for future Local Law 97 limits?
Building owners should evaluate current emissions, identify high-impact energy conservation measures, develop long-term capital improvement plans, and regularly monitor building performance to remain compliant.
Conclusion
Understanding Local Law 97 emission factors is one of the most important steps toward successful compliance. Electricity, natural gas, and district steam each carry different carbon intensities, meaning the type of energy your building uses can significantly influence annual greenhouse gas emissions.
Rather than focusing solely on reducing utility bills, property owners should evaluate how each energy source contributes to their overall carbon footprint. Strategic investments in energy efficiency, electrification, operational improvements, and long-term capital planning can help buildings meet current requirements while preparing for stricter future emissions limits.
As Local Law 97 continues to shape New York City’s path toward decarbonization, informed decision-making backed by accurate emissions analysis will remain essential for reducing compliance risks and protecting long-term building value.
