This estimator gives a fast indication of a building’s energy performance band from its actual annual consumption and floor area. It is an operational intensity screen — useful for landlords, property managers, and sustainability consultants deciding where to focus — not a substitute for a certified EPC produced by an accredited assessor.
How it works
The core metric is energy intensity: total delivered energy per unit of floor area, mapped to a band scale that depends on building type.
total energy = electricity kWh + gas kWh
intensity = total energy / floor area (kWh/m²/yr)
band = lookup(intensity, building-type band scale)
gap to next = intensity − next-band threshold (kWh/m²/yr)
annual saving = gap × floor area (kWh/yr)Better bands have lower intensity thresholds. The gap to the next band up tells you how much energy per square metre you must remove to improve the rating.
Example and notes
A 2,000 m² office using 180,000 kWh of electricity and 120,000 kWh of gas has a total of 300,000 kWh, giving an intensity of 150 kWh/m²/yr — a mid-table band for offices. To reach the next band you would target the lower threshold for that band and multiply the difference by 2,000 m² to size the saving in kWh per year. Use the indicative improvement cost only as an order-of-magnitude prompt; real costs depend on the specific measures, building fabric, and local prices.
EPC versus DEC: which applies to your building?
In the UK there are two main types of energy certificate for non-domestic buildings:
Energy Performance Certificate (EPC) — required for sale, letting, or construction of a building. It is based on the building’s theoretical energy performance modelled from its design and fabric using approved software (SBEM for most commercial buildings). It gives an asset rating that reflects the building as designed, not how it is actually operated. The rating scale is A (best) to G (worst), with bands defined by estimated primary energy per square metre per year.
Display Energy Certificate (DEC) — required for public authority buildings over 250 m² that are regularly occupied by the public. It is based on actual measured energy consumption from metered data — operational energy intensity in kWh/m²/year, which is what this estimator models. DECs must be displayed prominently and are renewed annually for larger buildings.
This tool estimates the operational-intensity band from your actual consumption, which most closely mirrors the DEC methodology. It is not a certified EPC or DEC.
Typical energy intensity benchmarks by building type
Energy intensity varies enormously by use. A data centre’s 24/7 IT load is fundamentally different from a school building occupied only during term time:
| Building type | Low-energy benchmark (kWh/m²/yr) | Average benchmark |
|---|---|---|
| School | ~80 | ~150 |
| General office | ~90 | ~200 |
| Retail | ~150 | ~350 |
| Hotel | ~200 | ~400 |
| Hospital | ~300 | ~600 |
Buildings in the low-energy range typically achieve band A or B. Average energy use typically falls in the C or D band. Buildings consuming significantly above average tend toward E, F, or G.
The MEES minimum energy efficiency standard (England and Wales)
The Minimum Energy Efficiency Standards (MEES) regulations require most privately rented commercial properties to achieve at least an EPC band E before they can legally be let. Regulations are expected to tighten further, with a band C target proposed for future years. Landlords with properties rated F or G who plan to re-let should treat an EPC improvement project as a near-term priority rather than a long-term aspiration. This estimator can help identify how far a building sits from the next band threshold before commissioning a full EPC survey.