CIBSE TM65 Assessment & Consultancy

Question: What is CIBSE TM65?

Answer: CIBSE TM65 Embodied Carbon in Building Services: A Calculation Methodology is guidance published by the Chartered Institution of Building Services Engineers for estimating the embodied carbon of mechanical, electrical and public health (MEP) equipment. It provides a consistent method for calculating the carbon emissions associated with manufacturing, transporting, installing, maintaining, replacing and disposing of building services products.

TM65 fills a significant gap, as manufacturer Environmental Product Declarations (EPDs) are often unavailable for building services equipment, which can account for 15 to 30 per cent of a building’s embodied carbon.

Question: Why is embodied carbon in building services important?

Answer: As buildings become more energy efficient, embodied carbon represents a growing share of whole life emissions. Building services equipment such as heat pumps, chillers, air handling units, switchgear, cabling and pipework has a relatively short life and is replaced several times during a building’s life, so its embodied carbon can be substantial. Understanding and reducing MEP embodied carbon is essential for whole life carbon assessments, net zero carbon targets and planning policies such as the London Plan.

Question: How does a TM65 assessment work?

Answer: TM65 provides two calculation methods. The basic method uses the product weight, material composition and a set of standard factors to estimate embodied carbon across the life cycle stages. The mid-level method uses more detailed manufacturer data where available. Where an EPD exists, that data takes precedence.

The assessment produces embodied carbon figures for each product and system, expressed in kgCO2e, which can be aggregated into the building’s whole life carbon assessment.

Question: When is a TM65 assessment required?

Answer: TM65 assessments are commonly required for:

• Whole Life Carbon Assessments under London Plan Policy SI 2
• Projects targeting net zero carbon or UK Net Zero Carbon Buildings Standard limits
• BREEAM Mat 01 life cycle assessment credits
• NABERS and LETI-aligned developments
• Clients with corporate embodied carbon reporting requirements
• Comparing design options such as heat pumps versus gas boilers

They are increasingly requested by planning authorities in London and by institutional investors.

Question: What are the related TM65 publications?

Answer: CIBSE has published a series of TM65 supplements, including TM65.1 for the UK (with more detailed factors for specific product types), TM65.2 for the assessment of heat pumps and heat networks, and TM65.3 for the assessment of building services products in existing buildings. Regional versions are also available. Consultants select the appropriate methodology based on the project location and system type.

Question: How can embodied carbon in building services be reduced?

Answer: Strategies include simplifying systems and avoiding over-specification, selecting lightweight or low-carbon products, extending equipment life through good maintenance, designing for disassembly and reuse, reusing existing plant in refurbishments, and choosing manufacturers with EPDs and low-carbon manufacturing. Early TM65 assessment allows these options to be compared while the design can still change.

Question: Why choose Syntegra Group for TM65 assessment and consultancy?

Answer: Syntegra Group’s building services engineers undertake CIBSE TM65 assessments as part of our whole life carbon, net zero carbon and BREEAM services across the UK. Because we design the M&E systems ourselves, we can integrate embodied carbon into design decisions, comparing options and identifying reductions rather than simply reporting a figure at the end.

We provide clear TM65 reports suitable for London Plan whole life carbon submissions, BREEAM evidence and corporate carbon reporting.