We are very proud to publish our first LETI Embodied Carbon Ratings for two of our projects

22.10.2021

Bennetts Associates are very proud to publish our first LETI Embodied Carbon Ratings for completed projects, which we believe is the first public use of the new declaration which we were involved in creating.

The declarations for our King’s Cross Sports Hall and for 11-21 Canal Reach are the culmination of over five years of embodied carbon calculation and reduction on both projects. The embodied carbon ambitions on both projects were instigated by Argent at a time when embodied carbon didn’t have the traction in the industry it has today, continued by us and the design team to dramatically reduce the embodied carbon compared to industry benchmarks, and taken to completion by BAM who continued making carbon savings and monitoring the as-built emissions up to practical completion.

We are not only proud of being the first to publish as-built ratings publicly, along with the background data, but also of the ratings themselves. The King’s Cross Sports Hall’s B rating means the project is meeting the RIBA 2030 Challenge ten years ahead of schedule, with the lowest carbon option at the time being chosen for almost every single building element. Alongside the circular economy story of the building, we see the project as being an exemplar for some time to come. At the same time, we view the result of a “D” rating for 11-21 Canal Reach as similarly impressive, whilst also highlighting how far the industry still has to go in a climate emergency. At 705kgCO2e/m2 (A1-5) 11-21 Canal Reach’s upfront embodied carbon is around 40% lower than “business as usual” despite being designed six years prior as a large, speculative office building, further highlighting the ambition of Argent, Bennetts Associates and BAM throughout the project’s life.

In Timber Square, one of our latest projects, we are demonstrating how we can take the lessons of both projects and our experience in re-using existing structures and combine them into a project that should get close to the results of the Sports Hall in the form of a large speculative office building in central London.

Lastly, as part of a ratcheting up of our existing sustainability targets in the run up to COP26 we are committing to publish an as-built (and ideally an in-design) declaration for all future projects so that we can be held to account and to support the industry in moving towards more ambitious, honest and transparent climate change claims about our buildings.

To take a full look at the embodied carbon rating and a more detailed LETI data template, download each from their project pages at the bottom of this page.

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Note: The Sports Hall rating in the original publication of this piece was previously published with an A+ embodied rating (the original declaration can be downloaded here). This was due to a mistake in the calculation process, outlined below. The news piece above has been adjusted to reflect the updated rating.

As well as being an exemplar of low embodied carbon construction, the building includes several circular economy principles, including design for deconstruction. In the initial analysis, the CLT planks, which have easily accessible reversible connections, were assumed to be re-used at the end of life, which we believe is a likely scenario, but not something we can guarantee. In this situation a compliant LCA would “transfer” the sequestration benefits out of the project at end of life, providing a similar end of life carbon balance to incineration, but the software used did not account for this and the issue wasn’t identified before publication.

As a result, and for simplicity, we have re-assessed the project using the product specific EPD end of life scenario, which assumes release of the sequestered carbon at end of life. The upfront carbon and the resulting LETI B rating, as well as the fact that this upfront carbon is almost matched by the amount of sequestered carbon, is not affected by this change. Regardless, we believe that even though the carbon calculation and rating do not show it, the use of design for deconstruction principles make the Sports Hall a lower impact project overall, and allow for a better end of life scenario.

As unfortunate as this mistake was, the fact that it was spotted reinforces the benefit of publicly disclosing data via the LETI rating system. We are grateful to Jane Anderson for raising the issue with us, and hope by updating the rating and explaining the correction, we are demonstrating a commitment to transparency and supporting the education of the industry.