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  • PublisherCIBSE
  • Product CodeTM65.1
  • Number of pages71
  • Publication DateDec 2021
  • ISBN9781912034581

TM65.1 Embodied carbon in building services: residential heating

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TM65.1 Embodied carbon in building services: residential heating

Embodied carbon in building services: residential heating (TM65.1) investigates the embodied carbon impact of heating and hot water equipment and strategies for use in residential buildings. In this document, embodied carbon refers to the greenhouse gas emissions associated with materials and construction processes (modules A1 to A5 (product and construction), B1 to B5 (in use) and C1 to C4 (end of life) defined in BS EN 15978:2011.

The embodied carbon calculations in this document follow the methodology outlined in CIBSE TM65, Embodied carbon in building services: a calculation methodology, as environmental product declarations (EPDs) are not yet widely available. The purpose of this document is to help engineers understand the embodied carbon impact of heating and hot water equipment, both at the product level and at the system level, to enable them to make informed design decisions early on in the design process.

The research for this document was conducted by Elementa Consulting, sponsored by CIBSE and Elementa Consulting. It was made possible thanks to the help of many manufacturers who shared information about their products, which enabled the calculation of embodied carbon at the product level, following the CIBSE TM65 methodology. For the residential typologies examined, this project is a first step towards understanding the embodied carbon implications of different heating strategies. If no EPDs are available, the results of this study can be used at the early design stage, but they should not replace project-specific calculations once a design has become more detailed. It should be noted that the results will evolve over time, as more manufacturer data is disclosed and EPDs are created.

The study focused on the embodied carbon of heating and hot water systems, and the mechanical equipment related to these systems, in a notional new-build three-bed terraced house and in notional two-bed apartments in multi-unit residential developments of different scales – a 15-unit development, a 100-unit development and a 2000-unit development (Figure 1). Ultra-low-energy building fabric standards (aligned to Passivhaus fabric performance) were assumed as this is the trajectory for the performance of new homes. Both individual and communal heating strategies were explored for the multi-unit residential schemes. In total, embodied carbon was estimated for about 30 different product types and 13 heating system options.

This study shows the embodied carbon impact associated with domestic heating systems can be expected to be quite high. For example, if the embodied carbon footprint of a new home is 800 kgCO2e,[1] the heating systems explored in this study would represent between 1% and 25% of the home’s total embodied carbon (excluding refrigerant). Furthermore, this study shows there is a large variation in embodied carbon between different system types, and the results are dependent on building scale and type. 

Table of Contents

  • Executive summary
  1. Embodied carbon in heating design
  2. Residential heating scenarios
  3. Key findings: product level
  4. Key findings: system level
  5. Conclusions
  • Appendix A: Methodology
  • Appendix B: Product results
  • Appendix C: Systems results
  • Appendix D: Complementary studies
  • Appendix E: Definitions

Authors: Louise Hamot, Clara Bagenal George, Yara Machnouk and Hugh Dugdale (Elementa Consulting)