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CIBSE Releases TM65 Addendum to Create Global Embodied Carbon Methodology

CIBSE Releases TM65 Addendum to Create Global Embodied Carbon Methodology

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Introba (formerly Integral Group/Elementa Consulting) has partnered with the Chartered Institution of Building Services Engineers (CIBSE) to launch an addendum to Technical Memorandum 65, the embodied carbon calculation methodology published in 2021. TM65 Embodied carbon in building services: Using the TM65 methodology outside the UK (TM65LA) is designed to create global consistency on how the embodied carbon of building services equipment can be assessed.

TM65 provides a methodology to estimate the life cycle embodied carbon of products used in building services engineering where no environmental product declaration (EPD) is available. Many assumptions inherent to the methodology in the 2021 publication are specific to the United Kingdom. This addendum complements TM65 by defining how local addenda may be developed and sets out how the methodology can be adapted outside the United Kingdom. It is not a standalone document and cannot be applied without first understanding TM65. To ensure that the CIBSE TM65 methodology is globally valid and globally consistent, CIBSE supports creating addenda to TM65 that are specific to locales outside of the United Kingdom by issuing TM65LA.

“The aim is to create global consistency with relevance locally. The TM65 methodology inherently relies on a set of assumptions that might differ in different countries for supply chain or geographical reasons. This guide sets the rules for creating consistent local addenda. A local addendum can be developed for a continent, a country, a state, a city or a region. The overarching methodology would be the same but applied with local assumptions and local carbon factors.” Louise Hamot and Clara Bagenal George

CIBSE TM65LA was authored by Louise Hamot and Clara Bagenal George (Introba), with contributions from Dr. Joe Jack Williams (Feilden Clegg Bradley Studios), Dr Julie Godefroy (CIBSE), Leonardo Polim (Introba), Louise Wilkinson, and Simon Wyatt (Cundall).

If you are interested in creating a local embodied carbon addendum, contact CIBSE at

Click here for full details on the drafting and submissions process, how to get started, and the full TM65 suite of publications.

Access TM65 Embodied carbon in building services: Using the TM65 methodology outside the UK (TM65LA) here.


CIBSE is a pioneer in responding to the threat of climate change. We support engineers in finding innovative ways to make buildings perform for individuals, the community, and the planet. As a leading professional engineering institution, CIBSE has over 22,000 members across 95 countries. Our membership is diverse and comprises a broad range of specialisms. CIBSE consults the government on construction, engineering, and sustainability, providing the resources needed to meet net zero targets in the United Kingdom, Europe, and worldwide. CIBSE is committed to supporting engineers and the vital role they play in creating a safe, sustainable future.   Learn more about CIBSE at

About Introba

Introba is an international network of engineers and consultants collaborating under a single deep green umbrella, providing a full range of building and district systems engineering, analysis, and sustainability consulting services. Introba runs projects in more than 30 countries with more than 100 net zero energy buildings designed to date and is proud to be a founding signatory of the World Green Building Council’s Net Zero Carbon Buildings Commitment and the MEP 2040 Challenge and primary authors of Embodied Carbon in Building Services: A Calculation Methodology (TM65) (CIBSE, 2021a) and Embodied Carbon in Building Services: Residential Heating (TM65.1) (CIBSE, 2021b).

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