CIBSE TM65 Overview

by Volkan Doda, London

The focus in the construction industry is rapidly and rightly shifting from operational carbon emissions towards the whole life carbon emissions, including the emissions that occur during the manufacturing, transport, installation, and disposal of the building services equipment. If not designed, operated, and disposed prudently, life-cycle emissions associated with the building services and refrigerants alone can dwarf the emissions due to the structural elements greatly scrutinised today.

In January 2021, CIBSE have issued their latest technical memorandum on “Embodied carbon in building services: a calculation methodology,” TM65:2021. This is a welcome document that provides much-needed guidance and consistency in MEP services embodied carbon calculations and reporting.

Based on our own work and research of limited publicly available benchmarks, the building services can be responsible for 10%-25% of the total embodied carbon emitted until practical completion in a typical fully serviced office building. This corresponds to many years of operational carbon emissions due to building use, released before the building is even occupied.

Unlike the other big embodied carbon emitters such as the building structure and envelope, the limited servicing life of the building services products means that their total lifecycle embodied carbon can be a yet greater proportion when the whole life-cycle of the buildings are considered. Similarly, building services can be responsible for up to 75% of the embodied carbon in light touch refurbishment and fit out projects depending on the scope of works.

To minimise this major source of carbon emissions, our most ambitious commercial office projects are targeting a budget of maximum 90kgCO2/m² (GIA) in embodied carbon emissions until practical completion for the building services, and tracking at about 110kgCO2/m² (GIA) with the best available products backed by verified EPDs based on our preliminary assessments.

However, these figures are high-level estimates informed by a very limited sample of available “Environmental Product Declarations” (EPD) and other relevant product information. In an ideal world, our assessments would be developed based on product specific EPDs produced by the manufacturers to declare the life cycle impacts of their products. Due to their complexity and lack of market interest until recently, EPDs on building service equipment have been largely unavailable. Authors of TM65 refer to a total of only 180 EPDs on all building service products globally and none of the 24 they have listed explicitly in the document are for products manufactured in the UK. Due to the lack of legislative framework in the UK, there are almost no EPDs available for locally manufactured building services products.

FIGURE 1 – Distribution of embodied carbon in building services based on a highly aspiring Atelier Ten reference project.

Even the limited number of EPDs available today often rely on outdated data due to the long time it takes to develop such documents for complicated building products with long supply chains. A large proportion of the embodied carbon in MEP products is driven by the energy mix used in manufacturing which has been undergoing a rapid change due to the ongoing grid decarbonisation and improvements in manufacturing processes. Consequently, we expect to see rapid shifts in the carbon profile of MEP products which are not fully captured by the currently available EPDs.

This is the large gap that TM65 aims to fill by engaging the supply chain and encouraging manufacturers to report lifecycle environmental impacts of their products on a regular basis. Based on the type of information manufacturers provide, TM65 prescribes two simplified stop-gap calculations that promote consistency in embodied carbon accounting until suitable EPDs become more widely available. Here, the emphasis is on “simplified” as the promoted methodologies are not necessarily “simple”. They still rely on sizable amounts of data from the manufacturers. Nevertheless, the emergence of a standardised methodology will likely and desirably encourage more developers and designers like us to request data from the supply chain. In response, more manufacturers will produce EPDs and start competing towards better lifecycle performance. At least this is what we anticipate based on the initial observations from the European markets that have adopted mandatory EPD policies.

Where data from the manufacturers is not available, the exercise will need to rely on benchmarks and databases, developed both internally and externally, for example by CIBSE. This is particularly relevant during the concept design and pre-planning stages when manufacturer engagement is limited. The standardisation framework established by TM65 is essential for the success of this effort as it will hopefully enhance consistency in MEP embodied carbon estimates during the early stages across projects and across life-cycle analysis practitioners until the national EPD databases reach a critical mass.

The simplified procedures proposed in TM65 are by no means perfect. There are gaps in the “science base” openly discussed in the appendix of the document which will have to be addressed as higher quality data from the industry emerges. Even so, it is paramount that the whole industry supports this effort to increase visibility and transparency on life-cycle impacts, and enable the development of more robust methodologies informed by verified data.

On this basis, following are the key immediate steps we all should adopt based on our review of the TM65:

  • When engaging with manufacturers, request EPDs for their products and emphasise that we highly value this as a potential requirement for carbon accounting during the procurement process.
  • If they cannot provide EPDs, ask manufacturers to fill in CIBSE’s standardised manufacturer form that lists the information necessary to complete the TM65 calculations.
  • Using standardised reporting form, share our TM65 outputs with CIBSE to support external database development.
  • Put highest priority on selection of low-carbon refrigerants wherever possible, as a high-carbon refrigerant can singlehandedly exceed the whole life carbon emissions of all other building services products combined (Figure 2).
  • Adopt the key principles highlighted in Section 2 of TM65 on “MEP Embodied carbon reductions,” including measures to minimise emissions due to refrigerants and overspecification of building service products.

FIGURE 2 – Whole life embodied carbon associated with refrigerants in few of the Atelier Ten projects.