Concept welcomes new CIBSE TM39 2026 guidance
Concept welcomes the publication of the updated CIBSE TM39 (2026) guidance, a major revision of the industry’s best-practice framework for building metering and monitoring.
The new edition reflects how much metering has evolved since the previous guidance was published in 2009, and for the first time includes thermal, gas, water and steam metering alongside electricity metering.
Importantly, it advocates an approach that establishes client and occupant need before the technical design.
This is an approach we’ve long taken at Concept. Whether we’re working with facilities management teams or landlords struggling with thousands of disconnected data points, or sites with little or no sub-metering, we start with the operational need first. This informs our approach to auditing, sub-metering strategy and design.
Why better metering matters
When designed well, sub-metering gives building owners and operators the information they need to make better decisions. It is increasingly important in helping organisations to:
- Demonstrate compliance with schemes such as ESOS and the upcoming Heat Network Technical Assurance Scheme (HNTAS)
- Manage tenant billing more accurately
- Identify inefficiencies and reduce unnecessary energy use
- Build stronger investment cases for equipment replacement and energy efficiency upgrades
- Understand actual equipment loads before replacing end-of-life plant, helping avoid over- or under-sizing new equipment
Addressing common pitfalls
TM39 (2026) addresses recurring issues found in building metering systems. In our experience, many buildings may already have sub-meters, but there is no schematic which shows exactly where these sub-meters are, or a clear hierarchy showing how everything fits together. In other cases, the infrastructure required to automatically read and collect the data may not be in place.
We also see situations where sub-meters are installed on relatively minor pieces of equipment, while energy-intensive plant is left unmetered. The result is little visibility of the systems that offer the greatest opportunity for energy savings. For example, a building may have a dedicated meter for a single toilet extract fan, but no meters showing how much energy is being used to run a swimming pool.
TM39: 2026 recognises these real-world challenges and places greater emphasis on designing metering systems that are useful throughout a building’s operational life.
What’s new in TM39: 2026?
The revised guidance has a much broader scope than previous editions. Alongside electricity metering, it now includes thermal, gas, water and steam metering, reflecting the growing importance of understanding whole-building performance as organisations work towards net zero.
The guidance also strengthens the connection between designers, project teams and operational teams, ensuring metering systems remain effective long after handover.
Some of the most significant updates include:
- Downloadable examples of how to document metering – the ‘golden thread’ that is passed on from designers and project engineers to the operations team.
- Expanded guidance on meter specification including hardware selection and sizing, plus tables showing advantages and disadvantages.
- Expanded guidance on meter accuracy classes
- New guidance on selecting a meter comms system
- Guidance to troubleshoot common metering installation issues
- New meter commissioning checklists – downloadable and fully customisable
- Guidance on data validation, including reconciling submeter data with the main utility meters, transferring data to data-collection systems, storing and displaying meter data.
- Good-practice minimum requirements for data visualisation, so users can understand energy use and how to achieve savings.
Aligned with new heat network regulations
The inclusion of heat metering is particularly significant as low-carbon heating technologies become more widespread. With schemes such as the Heat Network Technical Assurance Scheme (HNTAS) expected to increase the need for heat metering across many buildings, having a clear metering strategy from the outset becomes even more important.
How we can help
At Concept, we help FMs, landlords and building occupants gain visibility of energy and water use across complex estates. We develop bespoke sub-metering strategies to uncover how plant, systems and processes truly consume energy.
Get in touch with our metering consultants, or learn more about what we do. We’d be happy to have an informal conversation.
