Bouygues UK, acting as contractor on phase 2b of the housing estate regeneration, had spent two years developing their internal knowledge around whole life carbon assessments.
When phase 2b of the regeneration of the Wornington Green Estate in North Kensington completes in 2024[p1] , its residents will live in housing that has been the subject of one of the most accurate whole life carbon assessments undertaken for a project of its size and complexity.
Contractor Bouygues UK engaged Darren Evans to work with them collaboratively on assessing the whole life carbon of the 230 homes, comprising high-rise blocks and low-rise town houses. Darren Evans was brought on board to review the environmental impact data gathered by Bouygues UK and produce draft assessments for review.
The internal technical team at Bouygues UK already had several years of experience carrying out whole life carbon assessments. Working together, the two parties helped to develop each other’s knowledge and find areas for improvement within the whole life carbon assessment process.
A whole life carbon assessment takes the total embodied carbon of all the materials and products used within a project. It then adds the operational carbon, or emissions associated with energy and water use to heat and power the building. Whole life carbon is therefore defined as follows.
Embodied carbon + operational carbon = whole life carbon
“This is an unambiguous definition, because it includes everything associated with a building’s life,” says Brandon Wipperfurth, Senior Sustainability and Energy Consultant at Darren Evans. “Our approach is that it’s better to assess a project in terms of whole life carbon rather than embodied carbon, otherwise definitions of what is being measured can start to become more ambiguous.”
The embodied carbon of an individual product is determined by life cycle assessment (LCA). It takes into account the emissions resulting from the product’s manufacture, the need to maintain and replace it during the building’s life, and what happens to the product when the building is demolished or deconstructed.
Manufacturers report the results of LCA in the form of environmental product declarations (EPDs). As Brandon explains, however: “Individual products might have EPDs, produced to the best of a manufacturer’s ability and knowledge. But are the EPDs appropriate for the project? Some only provide generic information rather than product-specific information, for example.
“As a result, it’s easy to put unsuitable or even inaccurate information into a whole life carbon assessment.”
For Bouygues UK, challenging themselves to make the whole life carbon assessment as accurate as possible for Wornington Green meant engaging with additional expertise.
“Our carbon reduction plan for the project is to forecast, and try to measure, the carbon reductions we can make. But where do we start from? We had to understand what we wanted to do and why we wanted to do it, establishing a baseline as well as benchmarks, and then obtain the evidence that we’d achieved it,” says Romain Richli, Chief Climate Officer at Bouygues UK.
“This wasn’t the first time we’d undertaken whole life carbon assessments, having spent two years developing our internal expertise. However, if we only ever do these exercises alone then we won’t know where we’re risking falling foul of our own incorrect assumptions. We therefore decided to bring in outside help.”
Darren Evans produced an initial draft assessment, and the Bouygues UK technical team carried out an internal high-level review, interrogating the results based on orders of magnitude and shares of scopes and categories. They returned queries to Darren Evans, who produced a revised draft. Again, Bouygues UK reviewed it, this time in more detail, covering components, products and materials.
Brandon describes what made this project so unique: “It was the scale of it. This was a big development, and big developments are extremely complicated. This is one of the first high rise projects I know of that’s been done accurately. Bouygues UK are really at the forefront of this, and you can tell by how they gave us really specific detail, and how they didn’t want to miss anything out.”
“As an industry, we need to get better at measuring and assessing whole life carbon,” says Romain. “We’re all in the climate emergency together, so we must collaborate. Darren Evans shared our mindset. Our intention wasn’t simply to outsource a service and obtain a deliverable, it was to engage in a partnership to share our respective experiences and learn from each other.
“For some time we learnt by ourselves, as Bouygues UK have very strong internal technical capabilities. But at some point, there is a need to look out there and find levers to propel this knowledge further.
“Working with Darren Evans on this project has been a real success of collaboration.”
The benefits of collaboration were also felt by the Darren Evans team.
“I’ve very much learnt from Romain and his team on this project. We brought things to their attention as well,” says Brandon. “Bouygues UK really care about this, so the back and forth between us was really good. This depth of analysis isn’t yet normal – people want to show their assessments are low to win bids and tenders, so they’ll risk misusing information or omitting things to achieve better results.”
Romain shares this concern and describes how the industry needs to have something of a reality check. “The more detail we get into, the more likely we’ll actually have higher carbon emissions on projects – because we’ve sought to cover everything. It’s likely that our projects will look higher than others, and potentially higher for the coming year, while the whole industry is still learning. But that’s because we have exhaustive figures.
“We’re all learning, so it’s not the time to be making shortcuts. Only by being exhaustive and doing these analyses properly can we understand, learn and gain the complete expertise. Otherwise, claims are often made on very weak grounds. Only with that expertise can we then demonstrate the full extent of the savings we’re making.”
At the moment, whole life carbon assessments are not yet audited properly – which is what makes the collaboration between Bouygues UK and Darren Evans so unique. For Brandon, there is little doubt that embodied and whole life carbon will be made into regulation eventually, but the industry is still in the early stages of getting to grips with it.
“The robustness of assessment will come when the wider industry understands what needs to go into an assessment to make it as complete as possible,” he says “For a project like Wornington Green, hours and hours of time have to be put in to getting the assessment right. Until legislation requires it, not everybody will be able, or willing, to put similar effort in.”
M&E was the biggest area of shared learning on this project. “It’s an area of LCA not fully mastered,” says Romain, “so there are only a few EPDs available and generic carbon values are often used. Some of that generic data is five or ten years old, so it’s not accurate.”
Another issue is that the design of M&E is rarely complete before projects start on site, or sometimes even later on. Lengths of pipes and cables, for example, have not been fully designed or specified, so it’s difficult to establish an accurate quantity of material that will be used. Some of them, though, are heavy carbon contributors.
Installations feature circuit boards, which are lightweight components and easy to miss, but which have significant carbon implications due to the heavy metals used in their make-up. For Romain, accounting for all of this is to be seen as a positive challenge.
“We are engineers,” he explains, “and we’re not satisfied with partial answers. That’s why we have set ourselves the goal of going beyond high-level figures and understanding what they are really made of in order to draw conclusions.”
[p1]https://www.chg.org.uk/building-homes/regeneration/wornington-green-kensington/
One of the first high rise developments for which a whole life carbon assessment has been done accurately.
“This was a big development, and big developments are extremely complicated. Bouygues UK are really at the forefront of this, and you can tell by how they gave us really specific detail, and how they didn’t want to miss anything out.” - Brandon Wipperfurth, Senior Sustainability and Energy Consultant at Darren Evans.
“Darren Evans shared our mindset. Our intention wasn’t simply to outsource a service and obtain a deliverable, it was to engage in a partnership to share our respective experiences and learn from each other. Working with Darren Evans on this project has been a real success of collaboration.”
Romain Richli, Chief Climate Officer
