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Building Energy Intensity

Free Building Energy Intensity calculator with clear step-by-step results.

About Building Energy Intensity

Energy use intensity normalises a building's annual consumption by its floor area, which is what makes a small office comparable with a large one. The metric is simply annual kWh ÷ m², reported as kWh/m²/yr in most of the world and kBtu/ft²/yr in North America. Comparing against a benchmark for the same building type is the point of the exercise; energy per occupied hour then separates a genuinely inefficient building from one that is merely used intensively.

Formulas

Energy use intensity

EUI = annual energy (kWh) ÷ gross floor area (m²)

Normalised use

Per occupied hour = annual energy ÷ (occupied hours per week × 52)

Worked example

With the default values below, Building Energy Intensity returns Energy Use Intensity of 150.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Annual energy useminimum 0 kWh
180,000 kWh
Gross internal floor areaminimum 1 m²
1,200 m²
Occupied hours per weekaccepts 1–168 h
50 h
Benchmark energy use intensityminimum 1 kWh/m²/yr
120 kWh/m²/yr

Results

Energy Use Intensity
150.00 kWh/m²/yr
Energy Use Intensity
47.54 kBtu/ft²/yr
Against Benchmark
25.00%
Energy per Occupied Hour
69.23 kWh/h

Step by step

  1. 1Values used
  2. 2Energy use intensity
  3. 3Normalised use
  4. 4Energy Use Intensity= 150.00 kWh/m²/yr
  5. 5Energy Use Intensity= 47.54 kBtu/ft²/yr
  6. 6Against Benchmark= 25.00
  7. 7Energy per Occupied Hour= 69.23 kWh/h

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Formal energy ratings and disclosure schemes define floor area, fuel weighting and climate normalisation in prescribed ways. Use an accredited assessor for any regulatory or certification purpose.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Formal energy ratings and disclosure schemes define floor area, fuel weighting and climate normalisation in prescribed ways. Use an accredited assessor for any regulatory or certification purpose.

Frequently Asked Questions

What is a good EUI?

It depends entirely on building type and climate. Roughly 80-150 kWh/m²/yr is typical for offices, well over 300 for hospitals and data-heavy buildings, and under 50 for high-performance new build. Only compare like with like.

Why does energy per occupied hour matter?

A building running 24/7 will always have a high EUI. Dividing by occupied hours reveals whether the consumption reflects genuine use or wasteful out-of-hours operation, which is where most quick savings are found.

How do I convert to kBtu/ft²?

Multiply kWh/m² by 0.3169. The conversion combines 3.412 kBtu per kWh with 10.764 ft² per m².

Related Calculators

Building Energy Intensity – Calculate Energy Use Intensity