LEADER
Bigger, better data
“What’s the embodied carbon?” That’s a very important question for specifiers to ask about building materials and products – even if it’s far from a simple one to answer.
Producing an environmental product declaration (EPD), for example, involves exploring a spider’s web of supply chain connections, investigating travel distances and energy sources all along the way. As another illustration of this complexity, just look at the 2nd edition of the RICS Whole life carbon assessment, which has just come into force – 220 pages, compared to just 41 for the 1st edition published back in 2015.
There will always be assumptions involved in any calculation of the embodied carbon of a material or product – and therefore of a building. So it’s equally important that specifiers have some understanding of how carbon calculations are put together, in order to obtain an answer that is meaningful and comparable.
The good news is that there are a lot of people hard at work in this space. The updated RICS guidance aims to provide a structure to support more informed and comparable data, while the new tool from the Future Homes Hub makes it easier for housebuilders to measure carbon in a consistent way. Work is also under way to expand the amount of carbon data available, including a range of EPDs, at both an industry average level and for individual products.
It’s fantastic that specifiers and clients are asking for this data – the first step to managing anything is to measure it. But the next is to ensure they understand how to use the data appropriately. Location is a big factor, especially for a product like concrete, which is overwhelmingly local and seldom imported – around 92% of the concrete used in the UK is produced here, from locally sourced materials. So while the international manufacturerspecific EPDs held in many carbon databases would seem to give the most accurate measurement of as-built environmental impact, this is not necessarily the case.
UK sector EPDs, produced by pooling data from a number of manufacturers, may better reflect the latest local progress in decarbonisation. These collective EPDs are also really useful for early-stage design decisions, and can be considered a benchmark for what is achievable.
Guidance will likely continue to evolve with the more we measure and understand embodied carbon. Default wastage rates are another good example. Historically, the accepted wastage rate for concrete blocks was 20%, so if 100 were delivered to site, it was assumed that only 80 would be used. But when the MPA commissioned research to produce more up-to-date figures, we found that on today’s sites, the actual rate was closer to 5%.
All of this highlights that, while we all have learning to do, the industry is progressing all the time. Greater understanding will lead to greater clarity – and, ultimately, greater impact in terms of carbon reduction.
Elaine Toogood, Director, Architecture and Sustainable Design, The Concrete Centre