Materials Strategy and Embodied Carbon

Construction material related emissions account for 28% of the total global emissions from buildings and the construction sector. Concrete and cement production alone account for 8% of these emissions. In the next 30 years, the global primary material extraction and production is expected to double. In addition to emissions, there are a wide range of environmental consequences such as eutrophication and ecotoxicity of ecosystems, due to the extraction of raw materials and production process of major construction materials (e.g. concrete, Iron, copper).

Embodied carbon of construction materials is a measure of the global warming impact caused from the production (at the factory), the transporting of materials to the site, the construction process, emissions from removal and disposal at the end of its useful life. As buildings become more efficient by reducing the energy used for operation, the carbon impact from construction materials can account for up to 40-70% over the life span of a building. Therefore, calculating embodied carbon is integral for projects aiming to become net zero carbon.

Local Governments and major industry bodies like UK Green Building Council (UKGBC) and the Royal Institute of British Architects (RIBA) have all published guidance and targets to support the design delivery process. The Greater London Authority (GLA) now requires planning applications to produce a circular economy statement and a Whole Life Carbon (WLC) statement demonstrating how material related carbon impacts have been reduced. Embodied carbon targets have been proposed by RIBA and London’s Energy Transformation Initiative (LETI) for net zero carbon residential and commercial buildings.

Adoption of a whole life-cycle design approach to each material specified and enabling high-value recovery at the end of its life is a fundamental to reduce embodied carbon.

• Design buildings for longer life: By addressing how the proposed design approach could fully or partially reuse the existing structure, allowing future flexibility, adaptability and assembly, disassembly and recoverability.
• Be materially efficient: Perhaps the most reliable way to minimise embodied carbon and resource depletion is to minimise the quantities of material used. Designer’s should avoid oversizing components and look to design out some elements completely. For example, not having suspended ceiling at all.
  
• Enable loose fit: Minimise interdependency between different layers of a building (e.g. structural frame and the façade) enabling dismantling or removal of shorter life components for high value reuse
• Specify low embodied carbon materials and assess it in relation to its context: Specification and choice of materials based on the understanding of the embodied carbon impact alongside the knock-on effect to satisfy other operational performance requirements (e.g. thermal, acoustic and fire)

• Lack of consideration for whole life performance and just focussing on capital expenditure.
• Not setting a clear brief and prioritising embodied carbon early on can result in missed collaboration opportunities when developing project specific solutions.
• Variations in calculation results depending on the methods used, assumptions made and lack of good quality embodied carbon data; making their use in informing design decisions unreliable.
• No incentive for verification of post-construction embodied carbon

• Understand the proportion of up-front embodied carbon vs operational carbon and place this alongside whole life cost analysis to help make key design decisions.
• Request Environmental Product Declaration (EPD) certifications from suppliers. EPD’s provide a standard way of declaring the impacts of products through Life Cycle Assessment (LCA). Over 7000 EPDs are currently available and this is increasing, with numbers increasing gradually.
• The carbon information from the EPDs is used by various LCA software such as One Click LCA to calculate embodied carbon impact. However, be mindful that there is a much wider range of values for embodied carbon for the same product type, depending on the selection during the analysis, the results will vary significantly.
• Review options for reducing upfront carbon by using reclaimed materials. The Waste and Resources Action Programme (WRAP) have produced guidance.