Energy Use Intensity (EUI) Calculator

About the Energy Use Intensity (EUI) Calculator

Energy Use Intensity (EUI) is the single most important metric for comparing building energy performance. It normalizes energy consumption by building size, expressed as kBtu per square foot per year (kBtu/ft²/yr). A lower EUI means a more energy-efficient building.

This calculator converts your utility bills (electricity, gas, steam, etc.) into a combined EUI, then benchmarks it against national medians for your building type. The U.S. Department of Energy provides benchmarks through the Commercial Building Energy Consumption Survey (CBECS): the median office building is ~93 kBtu/ft²/yr, while hospitals run ~250 and warehouses ~35.

Understanding your EUI is the first step in any energy reduction strategy. If your building's EUI is significantly above the benchmark for its type, there are likely cost-effective efficiency improvements available — HVAC optimization, lighting upgrades, envelope improvements, or operational changes.

When This Page Helps

Use this calculator when you need one normalized number to compare a building’s energy performance across years or against peers. It is useful for benchmarking, early audit work, and showing whether a building is broadly efficient or simply large and expensive to run. The result gives owners and managers a quick way to prioritize whether controls, lighting, or envelope work should come first.

How to Use the Inputs

1. Enter your building's total gross floor area.
2. Enter annual electricity consumption (kWh from utility bills).
3. Enter annual natural gas consumption (therms or MCF).
4. Optionally add other fuel sources (steam, oil, propane).
5. Select your building type for benchmarking.
6. View your EUI and comparison against national benchmarks.
7. Explore potential savings from reaching benchmark targets.

Example Calculation

Tips & Best Practices

• Use 12 full months of utility data for accurate annual EUI.
• Include ALL energy sources — electricity, gas, oil, steam, district energy.
• Compare year-over-year EUI trends to track improvement progress.
• Weather-normalize EUI for fair multi-year comparisons.
• For ENERGY STAR certification, you need a score of 75 or higher.
• Typical office buildings can reduce EUI 20-30% with proven, cost-effective measures.

Understanding EUI Benchmarks

The CBECS (Commercial Buildings Energy Consumption Survey) provides national benchmarks: Office = 93, Retail = 78, K-12 School = 76, Hospital = 250, Hotel = 106, Warehouse = 35, Restaurant = 432, Grocery = 200 kBtu/ft²/yr. These are medians — 50% of buildings perform better, 50% worse.

Site vs Source Energy

A building using only electricity has a site-to-source ratio of about 2.8 (for the US grid average). A building using only natural gas has a ratio of 1.05. Mixed-fuel buildings fall between. Source EUI better represents total energy impact, while site EUI reflects on-site consumption and costs.

The Path to Net Zero

The Architecture 2030 Challenge targets source EUI reductions of 70% below the regional median by 2025, reaching net-zero by 2030. LEED and passive house standards push even further. Every EUI reduction starts with understanding where you are today.

Frequently Asked Questions

• What is a good EUI?

  It depends on building type. For offices, below 75 kBtu/ft² is good, below 50 is excellent. For hospitals, below 200 is good. Compare against CBECS medians for your building type — aim for the 25th percentile or better.

• What's the difference between site and source EUI?

  Site EUI measures energy consumed at the building. Source EUI accounts for generation and transmission losses (electricity loses ~67% before reaching the building). Source EUI is 2-3× higher for electricity-heavy buildings.

• How do I get my building's energy data?

  Review 12 months of utility bills for electricity (kWh), gas (therms), and any other fuels. Many utilities provide annual summaries. For multi-tenant buildings, request whole-building data through your utility's benchmarking program.

• What is ENERGY STAR Portfolio Manager?

  It's a free EPA tool for benchmarking building energy performance. It calculates your EUI and provides a 1-100 score relative to similar buildings nationally. A score of 75+ qualifies for ENERGY STAR certification.

• Does climate affect EUI?

  Yes, significantly. Buildings in extreme climates (hot-humid or very cold) naturally have higher EUIs. Proper benchmarking adjusts for climate using Heating Degree Days (HDD) and Cooling Degree Days (CDD).

• How can I reduce my building's EUI?

  The biggest levers are usually lighting retrofits, HVAC controls and tuning, envelope improvements, and better operating schedules. The right mix depends on what is driving your current energy use, so the benchmark is a starting point rather than the full diagnosis.