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Site EUI arithmeticFree

Building EUI
Calculator

Divide a user-entered annual site-energy total by the matching floor area. The result is a normalized arithmetic indicator, not a code, certification, or peer benchmark.

Who it's for: facilities managers and energy consultants normalizing a consistent 12-month site-energy total at post-occupancy operations review, by the floor-area boundary used for that same dataset.

1
Enter floor area + annual energy
Use gross floor area (GFA). Annual energy from utility bills or energy model — heating + cooling + lighting + plug loads
2
Confirm matching boundaries
The energy period, included fuels, and floor-area definition must be consistent before comparing results
3
Calculate site EUI
kWh/m²/yr only; select any external benchmark separately
EUI = total energy / floor area
EUI = annual site energy (kWh) ÷ floor area (m²). This tool does not convert fuels, weather-normalize consumption, define the floor-area boundary, or select a comparison target.
EUI Calculator
Site EUI · kWh/m²/yr
From utility bills or energy model. Include all end uses.

How to use this calculator

1
Enter the floor area (m²)
Use the same documented floor-area boundary that any later comparison dataset uses.
2
Enter annual site energy (kWh/yr)
Use a consistent 12-month total with all included fuels already converted to kWh on a declared site-energy basis.
3
Read the arithmetic result
The result is annual kWh divided by m². It does not assign a rating or determine compliance.

The formula

Site EUI = Annual site energy (kWh/yr) ÷ Floor area (m²)

Both inputs must use documented, matching boundaries. The formula itself does not define which fuels, meters, spaces, or operating period belong in the numerator or denominator.

Worked example

Example
A building with a documented 5,000 m² comparison area and 375,000 kWh of annual site energy has an EUI of 375,000 ÷ 5,000 = 75.0 kWh/m²/yr. Compare 75 only with a dataset using compatible energy and area definitions.

When this estimate will be off

  • Does not convert fuels or calculate source energy, greenhouse-gas intensity, cost, or weather normalization.
  • Does not choose a code, certification, peer group, climate, occupancy, or operating-hours benchmark.
  • Annual energy must cover exactly 12 months at full occupancy. A partial year, a major renovation period, or a vacant floor will skew the result low and overstate performance.
  • Mixed-use buildings with significantly different occupancy types need separate EUI calculations per zone — a single blended number is misleading for both parts.

Frequently asked questions

A common mistake: Does not convert fuels or calculate source energy, greenhouse-gas intensity, cost, or weather normalization.

EUI (Energy Use Intensity) is annual energy consumption per unit of floor area, expressed in kWh/m²/yr. It normalises buildings of different sizes so you can compare a 500 m² clinic to a 50,000 m² hospital — or track the same building year over year to measure improvement. Lower is always better.

This calculator intentionally does not answer that question. A meaningful comparison requires a compatible dataset and definitions for climate, occupancy, operating hours, fuels, site/source basis, and floor area.

No. It performs one division and returns a site-EUI indicator. Compliance and certification require their own methods, inputs, and approved benchmarks.

Sources

  • Declared arithmetic method — annual site energy in kWh divided by the user-entered comparison area in m²

This free Building Site EUI Calculator is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.