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TM54 Operational Energy Performance

The TM54 methodology looks at calculating predicted in-operation energy use.

It takes into account variability based on uncertainty within the input data, giving upper and lower expectations. It is a more robust alternative to relying on information from SBEM, which is intended for compliance checks only and may not give reliable predictions of operational performance.

TM54 is a Technical Memorandum published by CIBSE, and addresses the growing awareness that buildings in operation do not always perform as the designers predicted. This can apply to both energy cost and emissions.

Performance Gap CausesTM54 operational energy performance

The main reason for this ‘performance gap’ is that not all energy uses are accounted for in modern compliance methods. In particular, they do not address energy used by lifts and escalators, for catering facilities, or for server rooms.

This energy use can be substantial: in one case study, the National Trust HQ at Swindon, it was found that 60% of the energy use, that for the server room and the catering, was used in just 3% of the floor area, and more than doubled the operational energy use over the design estimates.

What Does TM54 Do?

TM54 provides building designers and owners with clear guidance on how to evaluate operational energy use more fully, and accurately, at the design stage. This enables more detailed accounting for operating hours and occupancy based on the intended use of the building.

The guidance sets out how the operational energy required for the building can be better estimated. As well as covering lighting, heating, ventilation and cooling and provision of hot water, it also considers lifts and escalators, small power loads, catering, server rooms and other plant and equipment.

How we Help with TM54 Evaluation

We can assist M&E teams, architects and contractors in better predicting the energy performance of their schemes, resulting in better buildings with improved outcomes for all stakeholders. We use Dynamic Simulation Modelling tools and a consultative approach to add maximum value to your team.

For more information on TM54: Evaluating Operational Energy Performance of Buildings at Design Stage visit the CIBSE site.

Would you like to discuss your project?

Call us for a chat on 0330 055 34 05 or email

Recent Projects

"HPW Architecture Ltd engaged Build Energy to ensure we delivered a commercially viable solution. From the very first introductory meeting they provided a first class service by helping to demystify the whole process and demonstrated excellent knowledge. We have found their experience and advice invaluable and would have no hesitation recommending their services"

Ben Jepson
- HPW Architecture

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