CIBSE embodied carbon methodology fast becoming the global standard for building services

Anastasia Mylona
Anastasia Mylona, Technical Director at CIBSE

Anastasia Mylona, Technical Director at the Chartered Institution of Building Services Engineers (CIBSE), explains why embodied carbon is increasingly important in building services design and outlines CIBSE’s calculation methodology which is rapidly being adopted internationally.

Building Services engineers have been at the forefront of efforts to reduce operational carbon emissions in buildings through improvements in the design, specification and optimisation of building services.

Alongside design impacts, the increased focus on the electrification of buildings combined with a rapidly decarbonising electrical grid has further accelerated the reduction in operational carbon. Consequently, the focus is now shifting to the carbon embodied in the manufacture, assembly, transportation, deconstruction and maintenance of building services systems.

LETI, the voluntary network of zero-carbon, built environment professionals, estimates in its Embodied Carbon Primer document that MEP services account for approximately 15% of embodied carbon in a new office. However, because most services will be replaced two or three times over the building’s lifespan, the real impact on a building’s whole life carbon is likely to be much greater in practice1.

Consultant Atelier Ten puts the proportion of embodied carbon attributable to building services systems even higher2; it estimates them to be responsible for up to one quarter of the carbon embodied in a typical, fully serviced office building.

Whole life carbon emissions

The term whole life carbon emissions refer to both a building services system’s operational and embodied-carbon emissions. Operational carbon is the carbon emitted by the energy consumed by the equipment in use. Embodied carbon includes emissions from the materials and systems used in construction of the equipment, such as those associated with the extraction of materials, their manufacture, repair, disassembly and even their disposal at the end of life.

Unlike operational energy, embodied energy savings have an immediate impact on a building’s whole life carbon. The savings are also mostly independent of occupant behaviour. One reason for the high proportion of embodied carbon in Building Services is the quantity of building services installed in a typical modern office. Another is that building services equipment is often made of metal and metal alloys with complex supply chains, often involving several manufacturing processes and sub-assemblies and long transport distances, all of which add to its embodied carbon.

A good starting point

A product’s environmental product declaration (EPD) would be a good starting point for those looking to select equipment with lower embodied carbon. The problem with this approach is that very few building services equipment manufacturers currently offer EPDs because of the complexity of products and their supply chains.


This is where CIBSE’s Technical Memorandum 65 Embodied carbon in building services: A calculation methodology is helpful.

TM65 provides a consistent approach to the calculation and reporting of embodied carbon for building services plant and equipment. In the document, embodied carbon is the greenhouse gas emissions associated with the manufacture of a product, its installation, maintenance, repair, replacement, and end of life. It covers the whole life cycle, excluding operational aspects and potential recovery, reuse or recycling of materials.

To be clear, CIBSE TM65 is not intended to replace a product’s EPD. Instead, where no EPD is available, it will allow an engineer to estimate the amount of embodied carbon in that product.

A digital version

To support engineers and manufacturers in using TM65, CIBSE has published a digital version of the Embodied Carbon Calculator tool. To use the digital Em-bodied Carbon Calculator tool, a manufacturer must first complete the TM65 Manufacturer Form3.

Using data from the manufacturer’s form, a user is then able to complete either a basic embodied carbon calculation, when limited information is available, or a more robust mid-level calculation. Once the user has added contact details and completed consent to publication details, the result may be used as a self-assessed value for the embodied carbon of the product.

Industry benefit

A further benefit to the industry is that CIBSE is using the information generated by the document to facilitate the development of an embodied carbon database for building services products. This will make it easier for CIBSE members to accelerate progress towards achieving net zero carbon buildings.

Although TM65 is UK specific, the same methodology is applicable to air conditioning, refrigeration and MEP products manufactured and installed anywhere in the world. To date CIBSE has published TM65ANZ Embodied carbon in building services: A methodology for ANZ to calculate embodied carbon for building services in Australia and New Zealand.

Sister organisation

CIBSE is also working with its sister organisation in the United States of America, ASHRAE, on adapting TM65 for the USA, Canada and Mexico. To this end CIBSE has published Embodied carbon in building services: Using the TM65 methodology outside the UK (TM65LA). While this document sets out how the embodied carbon methodology can be used outside of the UK, it is not a standalone document and cannot be applied without first understanding TM65.

More locally, TM65 has also been included in the GLA’s whole life carbon calculation process as part of the London planning process. 

CIBSE is also producing system specific publications. To date it has published:

  • TM65.1 Embodied carbon in building services: Residential heating, which investigates the embodied carbon impact of heating and hot water equipment and strategies for use in residential buildings
  • TM65.2 Embodied carbon in building services: Lighting, to enable lighting designers, specifiers, lighting engineers and manufacturers to understand the amount of embodied carbon that a light fitting contains.

When calculating embodied carbon, it should be remembered that not all the carbon impact of MEP systems is all down to the engineer. Premature replacement of some systems is attributable to retrofits and churn by tenants, which often result in systems being replaced earlier than is necessary. Similarly, the continued drive for fully repairing leases also means that it is common for landlords to replace heating and cooling systems, far in advance of the systems’ economic lifespan to help attract new tenants.

So, while TM65 will help engineers and specifiers select low embodied carbon options, the most effective way to reduce the embodied carbon associated with any building services system is clearly not to install it in the first instance. Or, if that is not possible, consider a simple and robust system, with reduced amounts of plant and equipment and/or a long lifespan.

While building services engineers have been at the forefront of efforts to reduce operational carbon emissions, the publication of CIBSE TM65 will ensure they are also at the forefront of efforts to reduce embodied carbon too.



2. articles/cibse-tm65-overview/ 

3. Available at TM65/manufacturerform

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