NYC LL97 Building Carbon Calculator

✓ Verified Content: All emission factors, building limits, and penalty calculations in this tool have been verified against NYC Local Law 97 of 2019, NYC Department of Buildings technical bulletins, and Urban Green Council compliance guides. See verification log

Introduction

NYC Local Law 97 (LL97) represents the most ambitious building emissions legislation in the United States, requiring buildings over 25,000 square feet to meet strict carbon emission limits or face significant annual penalties. This calculator helps building owners, consultants, and engineers quickly assess compliance status and estimate potential penalties for the 2024, 2030, and 2035 compliance periods.

The law affects approximately 50,000 buildings in New York City, representing roughly 60% of the city's built square footage. Understanding your building's compliance position is essential for financial planning, capital improvement decisions, and meeting the city's climate goals.

How to Use This Calculator

This tool provides instant LL97 compliance assessment. Follow these steps to analyze your building:

Step 1: Select Building Type

Choose the occupancy category that best matches your building from the dropdown:

Step 2: Enter Building Size

Input your gross floor area in square feet. This should match your Certificate of Occupancy or NYC PLUTO data.

Step 3: Enter Energy Consumption

Gather your utility bills for the past 12 months and enter:

Step 4: Review Results

The calculator displays:

• Current Emissions: Your building's annual carbon footprint
• Compliance Status: Green check (✓) for compliant, red X (✗) for non-compliant
• Estimated Penalty: Annual penalty amount if exceeding limits
• Carbon Intensity: Your kgCO2e per square foot for benchmarking

Input Parameters

Data Sources:

• Annual energy consumption should come from 12 consecutive months of utility bills
• Gross floor area should match the Certificate of Occupancy or PLUTO data
• For mixed-use buildings, the dominant use type typically applies

Calculation Method

Carbon Emissions Calculation

The total building emissions are calculated using NYC's prescribed emission factors:

Total Emissions (tCO2e) = (Electricity × 0.000288962) + (Natural Gas × 0.005311) + (Fuel Oil #2 × 0.01021) + (District Steam × 0.04493)

Emission Limit Calculation

The building's emission limit is based on occupancy type and gross floor area:

Annual Limit (tCO2e) = Gross Area (sf) × Building Limit (kgCO2e/sf) ÷ 1000

Penalty Calculation

Penalties apply when emissions exceed the limit:

Annual Penalty ($) = (Actual Emissions − Limit) ×$268/tCO2e

The $268/tCO2e penalty rate was set by the NYC Council and represents a significant financial incentive for compliance.

Code References

NYC Local Law 97 of 2019

• Section 28-320.3: Building emission limits by occupancy group
• Section 28-320.3.1: 2024-2029 compliance period limits
• Section 28-320.3.2: 2030-2034 compliance period limits
• Section 28-320.3.3: 2035 and beyond limits
• Section 28-320.6: Penalties for exceeding limits

Related NYC Regulations

• Local Law 33 of 2018: Benchmarking requirements
• Local Law 84 of 2009: Energy and water benchmarking
• Local Law 95 of 2019: Letter grade display
• NYC Building Code Chapter 32: Building emission limits

Output Interpretation

Compliance Status

Carbon Intensity

• Below 4 kgCO2e/sf: Excellent performance, likely compliant through 2035
• 4-8 kgCO2e/sf: Good performance, may need improvements for 2030+
• Above 8 kgCO2e/sf: Action required, likely facing significant penalties

Site EUI

Site Energy Use Intensity (EUI) provides context for energy performance:

• Below 50 kBtu/sf: High efficiency
• 50-100 kBtu/sf: Typical commercial building
• Above 100 kBtu/sf: High energy use, improvement opportunities

Limitations

This calculator provides estimates only and should not be used as official compliance documentation. Important limitations:

1. Simplified building types: Mixed-use buildings may have different limits calculated on a weighted-average basis
2. Emission factors: NYC may update emission factors; always verify against current regulations
3. Renewable energy: On-site renewables require separate calculation methodology
4. Deductions: Does not account for possible deductions (affordable housing, rent-regulated units)
5. Alternative compliance: Does not model prescriptive pathway or carbon offsets

For official compliance, buildings must:

• Benchmark in EPA Portfolio Manager
• Submit annual reports to NYC DOB
• Obtain certified professional verification for certain buildings

Example Calculations

Example 1: Office Building

A 150,000 sf Class A office building in Midtown:

• Electricity: 3,000,000 kWh/year
• Natural gas: 50,000 therms/year

Emissions: (3,000,000 × 0.000288962) + (50,000 × 0.005311) = 1,132 tCO2e/year

2024 Limit: 150,000 × 8.46 / 1000 = 1,269 tCO2e → ✓ Compliant 2030 Limit: 150,000 × 4.53 / 1000 = 680 tCO2e → Penalty: $121,176/year

Example 2: Multifamily Residential

A 75,000 sf apartment building in Brooklyn:

• Electricity: 750,000 kWh/year
• Natural gas: 40,000 therms/year

Emissions: (750,000 × 0.000288962) + (40,000 × 0.005311) = 429 tCO2e/year

2024 Limit: 75,000 × 6.75 / 1000 = 506 tCO2e → ✓ Compliant 2030 Limit: 75,000 × 4.07 / 1000 = 305 tCO2e → Penalty: $33,232/year

Related Tools

• Energy Code Compliance Calculator - IECC 2024 and Title 24 compliance
• Building Carbon Calculator - Operational carbon accounting
• Embodied Carbon Estimator - Material carbon analysis

References

1. NYC Local Law 97 of 2019 - Full text available at nyc.gov
2. NYC Department of Buildings - LL97 compliance guidance and FAQs
3. Urban Green Council - "Compliance Unlocked: Local Law 97" technical guide
4. NYC Mayor's Office of Climate & Environmental Justice - Building emissions data
5. EPA Portfolio Manager - Official benchmarking platform
6. ASHRAE - Building energy performance standards
7. NYC Accelerator - Free compliance advisory services
8. Building Energy Exchange - Case studies and best practices

FAQ

Q: When does LL97 take effect? A: The first compliance period (2024-2029) began January 1, 2024. Penalties apply starting 2025 for buildings exceeding 2024 limits.

Q: What buildings are covered? A: Buildings over 25,000 sf, or two or more buildings on a single lot totaling over 50,000 sf. Certain building types have exemptions.

Q: How are penalties calculated? A: $268 per metric ton of CO2e exceeding the building's limit, assessed annually.

Q: Can penalties be appealed? A: Yes, hardship exemptions and adjustment applications are available through NYC DOB.

Q: How do I reduce my building's emissions? A: Common strategies include LED lighting, HVAC upgrades, building envelope improvements, electrification, and renewable energy procurement.

Citation Guide

To cite this tool in reports or documentation:

APA Format: Simulations4All. (2026). NYC LL97 Building Carbon Calculator [Online tool]. Retrieved from https://simulations4all.com/simulations/nyc-ll97-calculator

For Professional Reports: "Preliminary LL97 compliance analysis performed using Simulations4All NYC LL97 Calculator. Official compliance requires benchmarking in EPA Portfolio Manager and submission to NYC DOB."

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Verification Log

All data, formulas, and regulatory references have been verified against authoritative sources.

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This calculator is part of the Professional Engineering Tools suite on Simulations4All. For official compliance, always verify with NYC Department of Buildings and consult a licensed professional.