EUI Calculator – Energy Use Intensity
Measure how efficiently a building uses energy. Enter annual consumption and floor area to compute site and source EUI values.
Include all heated/cooled space. Exclude parking garages or unconditioned storage.
Convert natural gas therms to kWh or kBtu before entering.
Used to estimate source EUI with EPA conversion factors.
Site EUI
61.42 kBtu/sq ft
Annual usage 1,535,400 kBtu
Source EUI
171.96 kBtu/sq ft
Benchmark Note
Moderate EUI. Compare against ENERGY STAR targets for your specific building category.
How to Use This Calculator
Gather annual energy data
Use utility bills or monitoring systems to total yearly electricity and fuel consumption. Convert different fuel units into kWh or kBtu.
Measure conditioned floor area
Include only heated or cooled areas to align with ENERGY STAR and ASHRAE guidance.
Select the primary fuel type
Choose the dominant fuel so the calculator can estimate source EUI using EPA conversion factors.
Formula
Site EUI = Annual Site Energy (kBtu) ÷ Conditioned Area (sq ft)
Source EUI = Site EUI × Fuel Source Factor
Example: 450,000 kWh/year × 3.412 = 1,535,400 kBtu. With 25,000 sq ft, Site EUI ≈ 61.4 kBtu/sq ft. Using electricity (factor 2.8), Source EUI ≈ 171.9 kBtu/sq ft.
About the Energy Use Intensity Calculator
Energy Use Intensity (EUI) reveals how efficiently a building converts energy into comfort and services. Lower EUI means less energy per square foot. This tool helps facility managers, sustainability teams, and auditors benchmark performance.
When to Use This Calculator
- Benchmarking: Compare your building against ENERGY STAR or ASHRAE targets.
- Retrofit planning: Quantify savings potential before and after efficiency projects.
- Portfolio management: Track EUI across multiple sites to prioritize upgrades.
- Compliance reporting: Generate inputs for ordinances that require public benchmarking (e.g., NYC LL84, Boston BERDO).
Why Use Our Calculator?
- ✅ Flexible units: Accepts kWh or kBtu inputs with automatic conversion.
- ✅ Source energy factors: Applies EPA multipliers to estimate source EUI.
- ✅ Quick benchmarking: Provides immediate insight into whether your building is efficient or energy-intensive.
- ✅ Mobile friendly: Use on tablets during site walkthroughs.
Common Applications
Facilities teams: Monitor EUI trends to schedule retrocommissioning.
Energy consultants: Gather pre-project baselines for performance contracts.
Corporate sustainability: Report annual progress toward carbon reduction goals.
Tips for Best Results
- Normalize energy data for weather (heating/cooling degree days) when comparing years.
- Separate process loads (data centers, labs) to understand their impact on EUI.
- Cross-check EUI with ENERGY STAR Portfolio Manager for benchmarking scores.
- Track site EUI monthly to spot anomalies that indicate equipment faults.
Frequently Asked Questions
What is a good EUI?
It depends on building type. Offices often target 50–80 kBtu/sq ft, while hospitals and data centers run higher. Compare against benchmarks for your use-case.
What’s the difference between site and source EUI?
Site EUI reflects energy used on-site. Source EUI adjusts for generation and transmission losses for a truer environmental impact.
Can I mix fuels?
Yes—convert each fuel to kBtu (or kWh) and sum before entering. Choose “Mixed fuels” to apply a blended source factor.
How often should I recalc EUI?
At minimum annually. Monthly tracking helps detect jumps in consumption caused by equipment failures or occupancy changes.