TM54 Operational Energy Modelling
CIBSE TM54 operational energy predictions to close the performance gap.
What it is
TM54 is the CIBSE methodology for predicting a building's in-use energy consumption at design stage — capturing regulated, unregulated, and small-power loads that Part L modelling excludes.
Who needs it
Clients targeting NABERS UK, BREEAM Excellent/Outstanding, WELL, or Net Zero Carbon commitments where predicted operational performance matters.
When it's required
RIBA Stage 3–4 for design decisions, and Stage 6 for post-occupancy verification.
What we provide
- [01]TM54 operational energy model to CIBSE methodology
- [02]Unregulated load and small-power modelling
- [03]NABERS UK design reviews
- [04]Post-occupancy verification against predicted performance
Related services
How this compares
Side-by-side breakdowns of the standards and routes most often confused with this service.
TM54 vs Part L
Part L models only regulated energy to prove regulatory compliance; TM54 predicts total in-use energy including everything the occupier will actually pay for.
Asset rating vs Operational rating
An asset rating scores the building as designed under standard conditions; an operational rating scores what the building actually consumed in use.
Common questions
[01]What is TM54?+
TM54 is CIBSE's methodology for predicting a building's in-use operational energy at design stage, going beyond Part L to include small-power and unregulated loads.
[02]What is Dynamic Simulation Modelling (DSM)?+
Dynamic Simulation Modelling is a computational method that simulates a building's performance hour by hour across a full year using real weather data, occupancy patterns and system behaviour. It predicts energy consumption, thermal comfort and indoor conditions far more accurately than steady-state tools, which is why it underpins Level 5 EPCs, TM52, TM54 and Part L compliance for complex buildings.
[03]What is a CIBSE TM54 operational energy assessment?+
TM54 predicts a building's real in-use energy consumption, including small power, catering, lifts, server rooms and out-of-hours operation, none of which appear in a Part L compliance model. It exists to close the performance gap between the regulated figure and the energy the occupier will actually pay for.
[04]Why does my building's EPC rating not match its energy bills?+
An EPC is an asset rating that models a standardised pattern of use, while your bills reflect real occupancy, hours, equipment and behaviour. A building can hold a good EPC and still perform badly in use, which is exactly the gap a DEC or a TM54 operational energy assessment is designed to expose.
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Same team on services design and compliance modelling. UK-wide, from London and York.