The Chartered Institution of Building Services Engineers (CIBSE) has published revisions to its Technical Memorandum 54: ‘Evaluating operational energy performance of buildings at the design stage.’ The revisions bring the guidance up to date by taking account of regulatory changes and advances in best practice.

CIBSE TM54 provides building designers and owners with guidance on how to evaluate operational energy use once a building’s design has been developed. It covers all energy uses, both regulated and unregulated.

The 2022 revision is cited as a method which can be used to meet the new requirement for large new non-domestic buildings to produce an energy forecast as stipulated in the latest revision to Approved Document L, effective from 15 June 2022.

The main evaluation principles remain the same as in the original document, with a step-by-step approach and scenario testing to improve the robustness of the design proposal calculations and advice to clients.

The revision takes account of advances in modelling expertise across the industry and the increased emphasis on high-performance buildings. It encompasses steady-state modelling as well as dynamic simulation and provides guidance on how to select the most appropriate modelling approach, and level of detail, for each project. The document makes clear that the methodology could be applied to any building, whether domestic or non-domestic.

Other updates include:

•   More emphasis on target setting, using the model to inform the design and controls strategy, and linking the model to the metering strategy and in-use evaluation

•   The creation of a TM54 “Implementation Matrix” to record assumptions and implementation of each step in the methodology; this should prove a valuable record for project teams and could also be used in communication with clients and building control bodies

•   Moving away from blanket overall management factors towards more specific testing of inputs influenced by operation and management

Julie Godefroy, CIBSE head of sustainability, said:

“CIBSE Technical memoranda offer guidance on recommended practices and the update to TM54 reflects recent developments in building performance evaluation throughout the project cycle. It ensures that the project teams have access to the latest information and guidance on evaluating operational energy use, contributing to high-performance buildings which deliver what they are supposed to.”