What Is EUI and Why Does It Determine Your Building's Fines?

Your building's EUI is basically how much energy it burns per square foot per year. That's it. That's the number the city uses to decide if you get fined.

If your EUI is above the limit for your building type, you're over. Below it, you're fine. The math isn't complicated. Finding the number is the hard part.

EUI in Plain English

EUI stands for Energy Use Intensity. It's one number that tells you how energy-hungry your building is compared to its size. A bigger building naturally uses more energy, so EUI normalizes that by dividing total energy by square footage.

The result is in kBtu per square foot per year. kBtu stands for "kilo British Thermal Units." It's the standard unit for measuring energy regardless of whether it comes from electricity, gas, steam, or oil.

Why kBtu and Not Kilowatt-Hours?

Because most buildings use multiple fuel sources. Your electricity comes in kilowatt-hours. Your gas comes in therms. Your steam comes in pounds. kBtu is the common denominator that lets you add them all together into one number.

How to Calculate Your EUI

The formula is simple. Getting the data together is the annoying part. Here's the step by step:

Step 1: Gather 12 Months of Energy Data

Collect all your utility bills for a full calendar year. Every source counts:

• Electricity
• Natural gas
• Fuel oil
• District steam
• Any other energy source your building uses

Step 2: Convert Everything to kBtu

Each energy source has a conversion factor:

Step 3: Add It All Up and Divide

Sum all your energy sources in kBtu. Then divide by your building's gross square footage. Done.

A Quick Example

Say you've got a 50,000 square foot office building. Over the past year, you used 500,000 kWh of electricity and 15,000 therms of natural gas.

• Electricity: 500,000 kWh x 3.412 = 1,706,000 kBtu
• Gas: 15,000 therms x 100 = 1,500,000 kBtu
• Total: 3,206,000 kBtu
• EUI: 3,206,000 / 50,000 = 64.1 kBtu/sf/yr

That's a real number you can compare to benchmarks, standards, and legal limits.

Why Regulators Care About EUI

EUI normalizes energy use by building size. A 10,000 square foot building and a 500,000 square foot building can be compared on a level playing field. A building with an EUI of 80 is less efficient than one with an EUI of 50, regardless of size.

It's also fuel-agnostic. Doesn't matter if your building runs on electricity, gas, or a mix. Everything gets converted to the same unit. This makes it easy for regulators to set one target across different building systems.

Several major building performance standards use EUI as their primary metric. Washington State's Clean Buildings Act and Denver's Energize Denver both set compliance targets in EUI. DC's ENERGY STAR scores are also derived from EUI data.

What's a "Good" EUI?

That depends entirely on your building type. A hospital running 24/7 with operating rooms will naturally have a higher EUI than an office that shuts down at 6pm. Comparing them makes no sense.

Here are typical ranges based on national ENERGY STAR Portfolio Manager data:

If your office building has an EUI of 95, it's in the typical range but nothing to brag about. If it's 45, you're in great shape. If it's 150, you've got a problem, and you're probably facing fines in any city with a BPS.

Site EUI vs. Source EUI

You'll run into both of these terms. Getting them confused can make you think you're out of compliance when you're actually fine, or vice versa.

Site EUI

This is the energy consumed at your building, measured by your meters. It's what you actually pay for.

Source EUI

This accounts for the total energy needed to deliver energy to your building, including generation, transmission, and distribution losses. Because power plants lose energy during generation and power lines lose energy during transmission, source EUI is always higher than site EUI for buildings that use a lot of electricity.

Weather Normalization

Energy use goes up in extreme weather. A brutal winter spikes your heating bill. A scorching summer runs your cooling nonstop. That's just physics.

Weather-normalized EUI adjusts for these swings by comparing actual weather to a long-term average. This prevents you from getting penalized just because it was a particularly cold year.

Most benchmarking tools, including ENERGY STAR Portfolio Manager, calculate weather-normalized EUI automatically. When you're comparing your building to targets or benchmarks, make sure you're comparing apples to apples: weather-normalized to weather-normalized.

How to Find Your Building's EUI

There are a few ways to get your number:

ENERGY STAR Portfolio Manager

If your building is registered in Portfolio Manager (and it should be if you're in a city with benchmarking requirements), your EUI is calculated automatically. Log in, check your property dashboard, and look for site EUI and source EUI.

Your City's Benchmarking Report

If your city requires annual energy benchmarking (NYC, DC, Boston, Seattle, Chicago, and many others do), your annual report includes your EUI. Many cities publish building-level data publicly, so you can even look up other buildings for comparison.

Manual Calculation

Gather your utility bills, convert to kBtu, divide by square footage. The formula is simple, but tracking down accurate data from multiple utility accounts and meters can take time.

Use BPS Check

Our compliance checker takes your basic building data and shows your EUI-based compliance status across every major BPS jurisdiction. Takes less than a minute.

What Drives a High EUI?

If your EUI is higher than you'd like, these are the usual suspects:

Old HVAC Equipment

Boilers, chillers, and air handling units past their useful life run at a fraction of their rated efficiency. A 30-year-old boiler at 65% efficiency versus a new one at 95% is a massive difference when you're running it all winter.

Poor Building Envelope

Single-pane windows, uninsulated walls, and air leaks force your HVAC system to work overtime. Envelope improvements are expensive but the impact lasts decades.

Inefficient Lighting

Still running fluorescent tubes? Your lighting energy use could be 3 to 5 times higher than it would be with LEDs. Lighting retrofits are usually the fastest, cheapest way to bring your EUI down. This should be your first move.

Wasteful Operating Hours

A building that runs its systems 24/7 when nobody's there after 6pm is burning money every night and weekend. Simple scheduling adjustments and occupancy sensors can cut consumption significantly.

Plug Loads

Computers, monitors, printers, servers, kitchen appliances. In modern offices, plug loads can account for 25 to 30% of total energy use. ENERGY STAR equipment and power management policies help, but this is the hardest category to control.

Domestic Hot Water

In multifamily buildings, hot water is often the single largest energy end use. Old boilers and lack of recirculation controls waste a surprising amount of energy. If you own multifamily, this is probably your biggest lever.

The Connection Between EUI and Fines

In cities that use EUI-based targets (like Washington State and Denver), exceeding the target means exceeding the law. Your penalty is directly tied to whether your EUI is above or below the limit for your building type.

In cities that use carbon emissions (like NYC's LL97 and Boston's BERDO), your EUI still matters because your emissions are derived from your energy use. Higher EUI means higher consumption, which means higher emissions. You can't lower your carbon intensity without lowering your EUI or switching to cleaner fuel sources.

Start With Your Number

Every compliance strategy starts with knowing your EUI. If you don't have it, get it. If you have it but haven't compared it to the legal limits in your jurisdiction, do that today.

The difference between a prepared building owner and one who gets blindsided usually comes down to this: the prepared owner knows their EUI, knows their limits, and has a plan to close the gap. The unprepared owner finds out when the penalty notice shows up in the mail.

Don't be that second person. Check your numbers.