Compares annual electricity and fossil-thermal (gas/oil) energy use per m² gross internal area against CIBSE TM46:2008 "Typical" category benchmarks, with a banded verdict and DESNZ 2026 carbon.
A simplified kWh/m² comparison, not a statutory Display Energy Certificate. Excludes TM46's weather (degree-day) and occupancy corrections.
Simplified comparison only. This is not a Display Energy Certificate; always verify against the full TM46 methodology where a formal rating is required.
About this energy benchmarking calculator
This free energy benchmarking calculator compares a building’s annual electricity and fossil-thermal (gas or oil) energy use, expressed per m² of gross internal area, against the CIBSE TM46:2008 “Typical” benchmark for its building category. It is aimed at UK M&E contractors, energy assessors and building services engineers who want a quick read on whether a building is better or worse than typical for its use, plus an indicative operational carbon figure, at survey or audit stage. It is a simplified kWh/m² comparison, not a statutory Display Energy Certificate. Everything runs in your browser. Nothing is uploaded.
How energy benchmarking is calculated
You pick one of the 29 TM46 Table 1 categories and enter the gross internal area (GIA) and annual electricity and fossil-thermal use. The calculator divides each fuel’s annual kWh by the GIA to get an intensity in kWh/m² (actual = annual kWh ÷ GIA), then forms a ratio against that category’s “Typical” benchmark (ratio = actual ÷ TM46 typical). A ±10% dead-band around 1.0 sets the banded verdict, better than typical below 0.9, near typical up to 1.1, worse than typical above. Operational carbon is annual kWh × the DESNZ 2026 conversion factor (electricity 0.13096, natural gas 0.18231 kgCO₂e/kWh, both editable). The method deliberately excludes TM46’s weather (degree-day) and occupancy corrections and the statutory CO₂-weighted A–G Operational Rating.
Frequently asked questions
Is this a Display Energy Certificate?
No. It is a simplified kWh/m² comparison against the CIBSE TM46:2008 typical benchmarks, and it omits the weather (degree-day) and occupancy corrections and the CO₂-weighted A–G rating that a statutory DEC requires. Use it for a quick sense-check, then commission a full assessment wherever a formal rating is needed.
Which TM46 category should I choose?
Pick the category whose description best matches the building’s main use, the tool lists all 29, from general office to cold storage, each with a one-line description. Four retail-type categories carry no fossil-thermal benchmark in TM46, so any gas or oil use there is flagged as unbenchmarked rather than scored.
Can I change the carbon factors?
Yes. Both default to the DESNZ 2026 figures for grid electricity and natural gas (gross calorific value), but you can overwrite the fossil-thermal factor for oil, LPG or biomass, and the electricity factor where you hold a supplier-specific value.