How do we reduce the carbon impact associated with design and materials? In this article we focus on the science of embodied carbon, and the plans we have as a business to help customers reduce embodied carbon.
What is embodied carbon?
Embodied carbon refers to the total impacts from all the greenhouse gas (GHG) emitted from the energy consumed in the extraction of raw materials, processing, transportation, manufacturing, installation, maintenance, and end-of-life. In contrast, the GHG emissions from the energy consumed in the use stage i.e., when the building becomes operational refers to the operational carbon.
There are different definitions of embodied carbon. We are aligned with the RICS Professional Statement ‘Whole life carbon assessment for the built environment’ and ‘UKGBC’s Net Zero Carbon Buildings: A framework definition’ which adhere to the EN 15978 terminology, as seen in the extract from EN 15978.
How is embodied carbon measured?
To measure the GHG emissions and quantify their potential environmental impacts on climate change, a methodology called Life cycle Assessment (LCA) is used. This LCA methodology offers a framework to measure sustainability of construction works through a suite of European Union harmonized standards which are developed & revised periodically including EN ISO 14025 and EN 15978.
DIAGRAM : Whole Life Carbon Assessment extract from EN 15978
Referencing the diagram extracted from EN 15978, the building industry’s current focus on embodied carbon refers to impacts from (1) product stage (modules A1 to A3) and (2) construction stages (modules A4 and A5), commonly referred to as upfront emissions. This means that we record and monitor the GHG emissions during stages A1 to A5. These GHG emissions are then converted into metrics indicating potential effects on the environment. One of the most common metrics used in reporting is global warming potential (GWP) which has a unit of kilograms of CO2 equivalent (kgCO2 e). This measure is also referred to as a carbon footprint.
How do we help our customers to reduce embodied carbon?
Through the choices we make in the process of design and construction; we help our customer’s reduce embodied carbon. We do this by reusing existing materials, which reduces embodied carbon impacts during product stage (modules A1 to A3). As well as this, our design-thinking approach draws on the principles of circular economy to design out waste, design for longevity, adaptability, disassembly and reuse which reduces embodied carbon impacts during end-of-life stage (modules C1 to C4) and adds to the benefits and loads beyond the system boundary (module D).
Our approach is to make holistic considerations embedded in whole life cycle assessment (WLCA). We carry out LCA studies that inform us of comparisons of potential solutions and its climate impacts that go beyond carbon emissions and indicate causal affects resulting in air pollution, impacts on health and wellbeing of the end-user, impacts extreme weather events such as flood risks, etc.
The implementation of Willmott Dixon’s Sustainable Procurement Policy allows us examination of relevant products specified in the Green Guide to Specification, review of embodied carbon impacts of materials informed by WLCA, and Environmental Product Declarations (EPD), where available, and industry intelligence to consider potential opportunities for reducing embodied carbon emissions of purchased materials and products. Therefore, we play our part in safeguarding natural resources, delivering value to our customers, improving resource efficiency, ensuring our processes aid traceability, transparency in procurement, positively enhancing biodiversity and minimizing impacts to the environment.
We develop a Waste Management Plan per project which includes preparation of a demolition audit or refurbishment audit prior to works commencing on site and enables us to reduce and eliminate avoidable waste by conducting calculated procurement of materials and using sustainable design alternatives. We work with suppliers to ensure materials are sourced sustainably, with mechanisms to return packaging to suppliers where possible for recycling thereby aligning with the principles of the circular economy.