The race to meet emissions reductions targets by 2030 means construction must now focus on embodied carbon, according to the winner of the RIBA President’s Award for Research – climate change
It is now globally accepted that human activity is the cause of rapid climate change. The postponed COP26 will now be held in 2021 in Glasgow, and all eyes will be on the UK during the negotiations to commit all countries to mass carbon reduction by 2030.
As the UK Green Building Council states, the built environment accounts for 40% of total annual emissions within the UK, giving the construction industry a clear responsibility to reduce emissions. However, it is imperative to steer industry professionals away from a narrative approach to carbon savings.
Architects have a pivotal position to collate data, control the project’s Whole Life Carbon (WLC) throughout the design process and enable big carbon savings early on.
Whole life carbon analysis
There are primarily two ways in which the built environment generates carbon emissions: from energy used during operation (operational carbon) and from the materials used for building and maintenance (embodied carbon). While the industry is progressively interrogating projects’ operational carbon, it is increasingly critical that we understand embodied carbon and WLC – and the combination of both – as we begin the transition to a regulated zero carbon economy.
Quantifying the full carbon emissions of a project over its lifetime has historically been a complex, specialist task. If calculations are done at all, it is late in the design process and they are rarely used to guide the early strategic decision-making which can significantly reduce emissions.
The evolution of H\B:ERT
In 2012, Hawkins\Brown and the UCL Institute for Environmental Design and Engineering (IEDE) co-funded a research project to improve the visualisation of architectural life cycle analysis. Dr Yair Schwartz completed a full Engineering Doctorate and, in addition, the basis for the Hawkins\Brown Emission Reduction Tool (H\B:ERT) was born. H\B:ERT v1, launched in 2018, measures embodied carbon through the materials tagged in a Revit model. It is available for all to use, free of charge, from our website.
In a new iteration, H\B:ERT has become a WLC tool. Fully integrated into the Hawkins\Brown Revit infrastructure, it is now an in-house tool. Data is transferred from Revit to a web portal offering infographics of the project’s WLC, which we have found essential for collaborative decision making and options appraisal at the earliest design stages.
The benefit of WLC is that it allows the study of the inter-relationship between embodied and operational carbon over the lifetime of a building. Through analysing H\B:ERT’s outputs, we have established five key actions for architects and design teams.
The case for retrofit: current RIBA 2030 Challenge targets are best achieved through targeting retrofit. Where this is not possible, the best reduction mechanisms involve low to medium rise construction, efficient form factor, omitting basements and a primarily timber structure, exploiting carbon storage. The use of bio-based materials where possible will contribute to reductions and in some building types enable regenerative solutions.
Early stage rules of thumb: Design teams often work on projects from competition stage, making quick decisions based on an aesthetic vision. Detailed analyses won’t be possible at this stage, but rules of thumb can help lock good choices into the design. The London Energy Transformation Initiative (LETI) Primer is a great resource for this.
Biggest carbon reductions at RIBA Stage 2: The greatest cuts can be made by testing comparative options for the structure and facade at this stage; then refining detail on other elements of the design as work progresses.
Balance operational and embodied carbon: A passive, fabric-first approach is the best way to reduce operational carbon, but this can increase embodied carbon, so optimisation for the particular design is crucial.
Iterative design process: The programme and consultant scopes must include the actions required, reflect an iterative design process and integrate carbon reductions into decision-making.
Reliable embodied carbon measurement depends on consistency. The Whole Life Carbon Network (WLCN) with RICS is doing great work in this area, but it will take time for the industry to upskill and there is no national funding for the required establishment of a national Environmental Performance Declaration (EPD) database. The integration of WLC measurement into the GLA London Plan is very welcome, providing a solid databank for better benchmarking.
Decarbonising the grid will contribute to lower carbon material and product manufacture, but will not solve the whole problem and may not be quick enough. As WLC overall comes down due to grid decarbonisation the circular economy will start to be prioritised, reducing the use of virgin material. This still comes with a carbon cost however.
H\B:ERT was developed to help architects make WLC evidence-based design approaches at the earliest design stages. Architects must now take the lead for a Net Zero future.
The Hawkins/Brown Emission Reduction Tool: Providing a data visualisation tool to enable architects to make informed decisions on their projects’ carbon emissions by by Louisa Bowles (head of sustainability at Hawkins\Brown) on behalf of Hawkins\Brown and UCL, is 2020 category winner for RIBA President’s Awards for Research: Climate Change