Low carbon concrete: a year on

A year on from the introduction of our UK low carbon concrete mandate, Peter Lyons, Director of our Specialist Trading Business Group, reflects on the impact it has had on accelerating our progress towards decarbonising concrete.

Mandating low carbon concrete in the UK

April 2023 marked an important milestone for our business. Following a long-term research programme, co-funded by Laing O’Rourke and Innovate UK, and in collaboration with the University of Cambridge and Sheffield University’s Advanced Manufacturing Research Centre (AMRC), we announced a switch to low carbon concrete on all our UK projects.

This mandate was a step change both for our business and the wider industry, proving that a range of low carbon concrete products can be successfully used as a like-for-like substitute for more traditional concrete mixes.  It also set a new minimum standard for us for low carbon concrete, aligned with the low emission concrete definition used by ConcreteZero.

Reflecting on our progress

In the first year of implementation, the switch to low carbon concrete has saved 6,719 tonnes of carbon (tCO2e) – a 15.5% reduction compared to FY22. This achievement reflects the strong uptake and compliance across the business. Although it wasn’t possible for projects in the later stages of delivery to adopt the mandate, through robust governance and monitoring processes we saw adoption increase throughout the year, with 60% of our live projects compliant at the close of the year. This will continue to improve through FY25.

We’ve gained some important learnings along the way:

• Leverage data to drive performance: We have raised concrete carbon data up our data quality hierarchy. While spend-based data is more accessible, we’re increasing the proportion of quantity-based data used in our calculations, as that gives us a much more accurate view of emissions. Where available, externally-verified environmental product declarations (EPDs) represent the most accurate source of data for us.
• Engage suppliers: We can’t drive progress alone, and we’re working closely with our concrete suppliers to innovate and to gain access to high quality concrete carbon data. This is essential for measuring and tracking our performance against our Scope 3 reduction targets. We’re now getting detailed project level mix designs and quantities for all our concrete, and carbon data from some of our key concrete suppliers. This will be an ongoing focus for us.
• Invest where it’s needed: Lower carbon concretes typically cure more slowly due to their reduced cement content, and require heat to accelerate the curing process. In a precast environment, we’ve been able to mitigate against the risk of low carbon concrete leading to an increase in programme time. We’ve invested more than £500,000 to upgrade the electric ovens and the power supply at our Centre of Excellence for Modern Construction (CEMC), where we manufacture all our pre-cast concrete products. The facility is powered by 100% renewable.

A spotlight on innovation

We recognise that progress only happens when we work together. Knowledge sharing and collaboration on research and development are essential to driving industry transformation, as our work demonstrates.

Our in-house expertise, including our specialist concrete technologists and technology and innovation team, combined with our best-in-class facilities at our technology centre in Essex and the CEMC, provide the optimal environment to test, trial and scale new technologies – and provide the capability to achieve this at a faster pace. While Ground Granulated Blast-furnace Slag (GGBS) is an important and readily available solution at present, we are working with a wide range of alternatives, such as calcined clay, identifying the best solutions for different use cases that can be deployed now and in the future.

We leverage these internal strengths to work with our partners – across academia, peers, suppliers, design consultants and clients – to transparently share our knowledge and advance the deployment of low carbon concrete at speed, for diverse use cases and with confidence.

Moving the needle on Scope 3

Scope 3 decarbonisation is the greatest challenge for our business and our industry.  95% of our emissions lie within Scope 3, and materials make up the bulk of those emissions. Decarbonising carbon-intensive materials – like concrete and steel – is critical, but it isn’t the only solution. The lowest carbon per kg of concrete is the one we don’t use, and we’re working closely with design partners and clients to develop innovative, carbon efficient designs that minimise the use of material.

We’re introducing a near-term 2030 Scope 3 target, aligned with science-based targets. This interim target will provide a clear and credible path towards our ambition to be a net zero company before 2050, and material decarbonisation will represent a significant part of that journey.

Looking ahead

We’re proud of our accomplishments to date, but we have much more to do. The progress we’ve made is the result of a significant investment in time, primary research and expert resource, and will remain a priority focus. Our business in Australia has now set embodied carbon limits for procured concrete – both directly and from subcontractors. We’re proud to be the first contractor to take this leading stance and hope to inspire others in our industry to follow suit. This decision is reflective of our Group-level commitment to drive concrete decarbonisation globally and industry.

Additionally, maintaining high quality carbon data will be the key to accelerating progress across our industry. While the industry is in the early stages of a long journey towards high data quality and integrity, it’s maturing rapidly.

Lastly, Environmental Product Declarations (EPDs) can be an important value creation lever for us and our clients. We’re requesting them from our suppliers, as well as developing them for some of our most frequently used standard products, like twin wall and lattice, so that our clients can be confident they are choosing products that will reduce the carbon footprint of their products.