Learn how initial and continuous commissioning optimizes building systems and eliminates energy waste.
BY NYC Energy Code Team
ON
31 August 2026
Understanding kBtu and Why It's the Standard Energy Metric
If you have ever reviewed an energy audit, benchmarking report, or capital plan for a commercial or multifamily building in New York City, you have undoubtedly encountered a measurement that sounds unfamiliar: kBtu.
For property owners, co-op boards, and facility managers who are not mechanical engineers, the term can feel like academic jargon. Yet kBtu is the universal foundational unit that enables meaningful comparison of energy consumption across buildings of different sizes, ages, and fuel combinations.
The core problem it solves is simple: modern buildings consume multiple different forms of energy. A single property might draw grid electricity for lighting and elevators, burn natural gas in space heating boilers, consume fuel oil for domestic hot water backup, and purchase district steam from Con Edison. Each utility bills in completely different physical units:
The Universal Energy Currency
Electricity is measured in kilowatt-hours (kWh), natural gas in therms or CCF, fuel oil in gallons, and district steam in thousands of pounds (Mlbs). You cannot simply add kWh to therms. Converting all fuel streams into kBtu creates a common thermal currency that makes whole-building energy tracking possible.
What Does kBtu Mean?
kBtu stands for one thousand British Thermal Units (1,000 Btu).
Historically, a British Thermal Unit represents the amount of heat energy required to raise the temperature of one pound of liquid water by one degree Fahrenheit at sea level. In commercial real estate, you will also encounter MMBtu, which represents one million Btu (or 1,000 kBtu).
Converting Utility Fuels into kBtu
To understand how disparate utility bills merge into a single energy profile, energy engineers apply standardized thermodynamic multipliers:
| Utility Fuel Source | Billed Physical Unit | Multiplier Factor | kBtu Equivalent |
|---|---|---|---|
| Electricity | 1 Kilowatt-hour (kWh) | × 3.412 | 3.412 kBtu |
| Natural Gas | 1 Therm | × 100.0 | 100.0 kBtu |
| Natural Gas (Volume) | 100 Cubic Feet (CCF) | × 103.7 | 103.7 kBtu |
| #2 Fuel Oil | 1 Gallon | × 138.5 | 138.5 kBtu |
| #4 Fuel Oil | 1 Gallon | × 145.0 | 145.0 kBtu |
| District Steam | 1,000 lbs (Mlbs) | × 1,194.0 | 1,194.0 kBtu |
What Is EUI (Energy Use Intensity)?
Total kBtu alone does not tell you whether a building operates efficiently. A 500,000-square-foot Midtown commercial tower will naturally consume far more total kBtu than a 25,000-square-foot walk-up in Brooklyn.
That is where Energy Use Intensity (EUI) becomes vital. EUI normalizes total annual energy consumption by gross floor area:
EUI Formula
EUI = Total Annual Energy Consumption (kBtu) ÷ Gross Floor Area (sq. ft.)
Expressed as: kBtu/sq ft/year (kBtu/ft²/yr)
A Concrete EUI Example
Building A: Consumes 20,000,000 kBtu/year across 100,000 sq. ft. → EUI = 200 kBtu/sq ft/year.
Building B: Consumes 40,000,000 kBtu/year across 500,000 sq. ft. → EUI = 80 kBtu/sq ft/year.
Even though Building B uses twice as much total energy, it is 2.5 times more energy efficient per square foot than Building A.
Site Energy vs. Source Energy: What's the Difference?
When viewing your EPA ENERGY STAR Portfolio Manager report, you will notice two distinct EUI figures:
- Site Energy (Site EUI): The raw energy directly delivered to and consumed on-site at the property, as reflected on your monthly utility meters.
- Source Energy (Source EUI): Accounts for the total primary fuel consumed to generate, transmit, and deliver that energy to the building, incorporating power plant thermal inefficiencies and transmission line resistance losses.
Why Source Energy Matters to the EPA
The EPA uses Source Energy to calculate 1–100 ENERGY STAR scores because it provides an equitable comparison between an all-electric building and a property burning on-site fossil gas. In New York, generating and transmitting grid electricity has a source-to-site conversion ratio of approximately 2.80, while delivered natural gas is close to 1.05.
How kBtu Connects to NYC Energy Regulations
1. Local Law 84 Benchmarking & LL95 Energy Grades
Every year by May 1st, NYC buildings over 25,000 sq. ft. must upload 12 months of utility consumption into Portfolio Manager. Portfolio Manager converts the multi-fuel data into kBtu, computes Weather-Normalized Site and Source EUI, and assigns the building an energy score from 1 to 100, which determines the posted Local Law 95 Letter Grade (A, B, C, D, or F).
2. Local Law 87 Energy Audits & Retro-Commissioning (RCx)
Under LL87, covered properties must complete an ASHRAE Level II Energy Audit every 10 years based on tax block numbers. The audit breaks down the building's total kBtu consumption into specific end-uses (space heating, cooling, domestic hot water, fans, lighting, and plug loads) to identify high-ROI Energy Conservation Measures (ECMs).
3. Local Law 97 Carbon Limits: kBtu vs. Emissions
Crucial Distinction: LL97 enforces limits on greenhouse gas emissions (metric tons of CO2 equivalent), not total kBtu. Because each fuel type has a different carbon coefficient (natural gas produces 0.00005311 tCO2e/kBtu, while fuel oil produces 0.00007421 tCO2e/kBtu), two buildings with identical kBtu consumption can have dramatically different carbon penalty liabilities.
5 Common Mistakes Property Owners Make with kBtu
Mistake 1: Treating kBtu as a Utility Bill Line Item.
Utilities bill in kWh, therms, or gallons. kBtu is an analytical engineering
conversion metric.
Mistake 2: Comparing Total kBtu Without Factoring Square
Footage. Raw kBtu volume favors smaller, inefficient buildings over
large, well-optimized towers.
Mistake 3: Comparing EUI Across Different Property Types. An
office building (EUI ~65) cannot be compared to a high-ventilation hospital (EUI
~220) or restaurant space.
Mistake 4: Uploading Incorrect Billing Units into Portfolio
Manager. Entering CCF instead of therms or Mlbs instead of lbs
creates massive 100x data distortions.
Mistake 5: Assuming kBtu Directly Determines LL97 Penalties.
Carbon caps depend on fuel emissions factors and regulatory occupancy formulas,
not total thermal Btu alone.
Final Takeaway
Understanding kBtu and Energy Use Intensity (EUI) gives building owners and facility managers the clarity needed to interpret energy reports, diagnose HVAC operational faults, and verify retrofit performance.
By unifying multi-fuel utility streams into a standardized metric, kBtu transforms disparate electricity, gas, oil, and steam bills into actionable data for Local Law 84 benchmarking, Local Law 87 audits, and capital planning.
Partner with a certified energy engineering team to establish an accurate, multi-year energy dashboard that benchmarks your EUI against peer NYC properties and protects your portfolio against compliance penalties.
Frequently Asked Questions
kBtu stands for one thousand British Thermal Units (1,000 Btu). It is a
standardized thermodynamic unit of thermal energy used to convert and
aggregate disparate fuel sources into a single common metric.
Buildings consume multiple utility sources—electricity in kWh, natural gas
in therms, fuel oil in gallons, and steam in Mlbs. Converting all sources to
kBtu allows energy engineers to calculate total whole-building consumption
accurately.
EUI stands for Energy Use Intensity. It represents total annual building
energy consumption divided by gross floor area, expressed as kBtu per square
foot per year (kBtu/sq ft/yr).
There is no single universal good EUI. Benchmark averages depend on
occupancy type, operating hours, and climate: NYC multifamily buildings
average 60–90 kBtu/sq ft/yr, office high-rises average 50–80, whereas
hospitals and restaurants often exceed 150–300.
No. A kilowatt-hour (kWh) specifically measures electrical energy (1 kWh =
3.412 kBtu). A kBtu is a universal thermal measurement that applies equally
to electricity, gas, steam, and oil.
Not necessarily. While lower EUI indicates lower energy intensity, building
use, tenant density, ventilation rates, operating schedules, and thermal
comfort must be factored in before drawing conclusions.
Yes. NYC Local Law 84 annual benchmarking requires covered buildings to
input all utility meters into EPA ENERGY STAR Portfolio Manager, which
computes site and source EUI in kBtu/sq ft/yr to generate building energy
letter grades (A–F).
No. Local Law 97 regulates greenhouse gas carbon emissions (tCO2e), not raw
energy volume. While lowering total kBtu reduces emissions, fuel carbon
coefficients mean burning 100 kBtu of natural gas produces more emissions
than 100 kBtu of clean grid electricity.
Tracking weather-normalized EUI over multiple years reveals long-term
performance trends, detects equipment scheduling faults or hidden leaks,
verifies energy retrofit ROI, and prevents compliance surprises.
Yes. Convert your 12 months of utility consumption into kBtu using standard
multiplier factors, sum the total kBtu, and divide by the gross interior
square footage of your building.