Construction materials’ embodied carbon emissions are responsible for 10% of the UK’s total greenhouse gas emissions. At 64 million tonnes of CO2e per year, the total is more than the country’s aviation and shipping emissions combined.
With the industry reducing operational energy in buildings through more energy efficiency measures, tackling embodied carbon is the next big challenge.
CIBSE believes that there is an urgent need for regulation and, in February, it joined forces with other institutions and construction bodies to send a consistent message to UK political leaders.1
Together with the UKGBC, IStructE, ICE, CIOB, CIC, RIBA, RICS, ACE, UK Architects Declare, and Part Z, the Institution called on party leaders to commit in election manifestos to reducing construction embodied carbon emissions within two years of taking office. By 2028, it wants them to introduce legal limits on upfront embodied carbon emissions for projects with a gross internal area of more than 1,000m2 or more than 10 dwellings.
Embodied carbon is the carbon emissions of a building before it becomes operational. It is associated with materials and construction processes throughout the whole life-cycle of a building, including during the manufacture of building materials, their transportation, and the construction process. It also refers to the carbon produced in maintaining the building and, eventually, demolishing it, transporting the waste and recycling it.
Embodied carbon represents 30% of a building’s total carbon on average, the rest being operational carbon. Our efforts to reduce operational carbon could increase the proportion of embodied carbon to 80% of a building’s total carbon over time.
According to Greater London Authority’s Whole Life-Cycle Carbon Assessment guidance, the embodied carbon of building services in new projects is, on average, 25% – and, in retrofits, up to 75%. This is because of complex systems containing multiple components created using intense manufacturing processes. The use of refrigerants, high replacement rates, and a global supply chain also contribute to high embodied emissions.
Understanding the embodied carbon of products and their components is crucial to creating less carbon-intensive products. This information is usually provided in environmental product declarations (EPDs). However, these are available for few products because of the high cost of producing EPDs due to the complexity of MEP equipment.
CIBSE’s TM65 Embodied carbon in building services: a calculation methodology provides a simple way to estimate the embodied carbon of building services equipment where an EPD is not available. It has been adapted for use in Australia and New Zealand, and two further regional addenda are due in 2024 (USA/Canada/Mexico and UAE).
TM65.1 Embodied carbon in building services: residential heating, published in December 2021, provides the embodied carbon for residential heating systems.
TM65.2 Embodied carbon in building services: lighting, published in August 2023, gives lighters a tool to estimate the embodied carbon of lighting products.
CIBSE is set to launch the next in the series – TM65.3 Embodied carbon in building services: logistics – and one covering HVAC in offices is due later this year.
To reduce embodied carbon, engineers should first reduce the need for MEP kit by prioritising passive design options, and avoid overengineering by carefully considering the design and location of systems. Also avoid oversizing by understanding the building requirements (indoor environment, occupant profiles, HVAC demand cycles) and sizing systems accordingly. We tend to size systems for the worst-case scenario, adding further capacity, which leads to oversizing.
Finally, we need to understand the embodied carbon of products, including reusability and recyclability, to help us select the ones with a lower carbon footprint. By minimising the need for MEP equipment, capital and operational costs can be reduced significantly. Reducing dependence on equipment can also increase the resilience of buildings and the built environment to extreme weather.
Decreasing the use of MEP equipment plays a pivotal role in mitigating the carbon footprint of buildings. This aligns with our decarbonisation goals and supports our efforts to reduce our environmental impact.
References:
- Embodied carbon regulation – alignment of industry policy recommendations, CIBSE February 2024, bit.ly/ECRFeb2024