Materials & Supply Chain

We support our supply chain to improve its environmental and social impact.

Our Now or Never interventions are designed to lead our industry from the front, guiding our people and supporting our supply chain to respond to the climate challenge. We have committed to reducing embodied carbon emissions from purchased goods and services by 55% by 2030 and by 100% by 2040, against a 2018 baseline.

^{1. In line with our Science Based Target, this includes purchased goods and services from category A suppliers (which makes up at least two thirds of scope 3 emissions).}

All supply chain partners must comply with our Sustainable Procurement Policy, developed in line with ISO 20400. The policy sets out how we and our supply chain can influence procurement choices to reduce the use of primary resources and minimise the environmental and carbon impacts of the projects we deliver.

We worked closely with our key trade partners - those with the greatest potential for carbon reduction - to increase levels of reporting through the Supply Chain Sustainability School's (SCSS) carbon emissions tool. All our key partners are required to commit to achieving net zero in their own operations by 2030. By the end of 2025, 96% of our partners were registered with the school, and 182 had submitted their carbon data.

Using data from the previous reporting year, we hosted three carbon reduction trade workshops, grouping partners by similar operations and carbon profiles. This helped identify practical opportunities to reduce scope 1 and 2 emissions while improving carbon literacy. A total of 82 key trade partners attended.

We are part of the SCSS Climate Action Group (CAG), which brings together main contractors from across the industry to drive reductions in carbon emissions throughout the built environment value chain, covering the products, works, and services procured.

Reducing carbon in our materials

Carbon emissions associated with materials and construction processes throughout the whole lifecycle of a building or infrastructure are referred to as ‘embodied carbon’. Embodied carbon from the construction and refurbishment of buildings currently makes up 20% of UK built environment emissions (UKGBC).

Typically, these emissions come from any processes, materials or products used to construct, maintain, repair, refurbish and repurpose a building.

These emissions arise from the extraction of raw materials, their manufacture into products, transportation to site, construction and installation, and continue through the life of the building to eventual deconstruction and disposal.

Addressing emissions from construction materials is complex, but it also presents an opportunity to build a more transparent and resilient supply chain. Achieving zero scope 3 carbon emissions will require significant change, and we are committed to working with partners to support that transition and to deliver all our buildings with net zero embodied carbon by 2040.

By the end of 2025, we had completed embodied carbon assessments on 93 projects. These assessments give our customers a clearer understanding of the carbon impact of their buildings and, where relevant, present options to reduce it.

At Coleg Gwent’s Crosskeys Campus near Newport (below), 57 tonnes of carbon were saved by increasing the GGBS (Ground Granulated Blast Furnace Slag) content of the foundations and ground floor slab to 50%, which reduces the amount of cement required and associated embodied carbon.

Sustainable Steel

Structural steel is one of the biggest contributors to embodied carbon on many of our projects. Our embodied carbon assessments consistently show that steel-framed buildings lock in a significant share of total carbon within the primary structure, and the manufacturing route is critical.

Steel produced via a Basic Oxygen Furnace relies heavily on virgin iron ore and is highly carbon intensive, whereas Electric Arc Furnace (EAF) steel, which uses up to 100% scrap, can reduce carbon emissions by up to 80% per tonne.

In response, we have made a deliberate shift to prioritise EAF steel wherever feasible. Typically, 70–75% of structural frame components can be sourced using EAF technology, and many of our projects are already demonstrating embodied carbon savings as a result. For example, Leighton Linslade Leisure Centre (below) saved 185 tonnes of embodied carbon - a reduction of 73% per tonne.

Across five projects in our South and Wales & West regions (London River Academy, Barnes Hospital, Weybridge Health Centre, Bransbury Leisure Centre, and Coleg Gwent - Crosskeys), using EAF steel in the primary structural frame saved a combined total of more than 850 tonnes of embodied carbon.

Eight of our ten key steel supply chain partners are now sourcing and supplying EAF steel. Most is currently imported from mainland Europe, but even accounting for transport emissions, EAF steel still carries significantly lower whole-life carbon than UK-produced BOF steel.

The planned Tata Steel EAF facility in South Wales, expected by 2027, will be an important step in making low-carbon steel more readily available domestically.

Promoting timber construction

Timber construction can play a significant role in creating a more sustainable built environment by reducing embodied carbon. It also supports the ambitions of many customers who are increasingly promoting low carbon initiatives – such as the Department for Education’s ‘GenZero’ programme – and aligns with the commitments set out in Now or Never.

The UK Government’s Timber in Construction Roadmap highlights the need for better timber and whole-life carbon data and sets out commitments to increase timber use in support of housing delivery. At the same time, policy is moving towards stronger carbon accounting and greater responsibility for nature. There have been growing calls for embodied carbon assessments to be incorporated into Building Regulations, while the UK Net Zero Carbon Buildings Standard (UKNZCBS) now sets embodied carbon limits across 13 building types, tightening annually to 2050.

However, timber can still be more expensive than steel or concrete on larger projects, which can limit its adoption. Costs could potentially be reduced if the carbon stored within timber were formally recognised, making it easier for projects to meet embodied carbon targets and reducing the need for more costly low carbon technologies. At present, though, there is no verifiable standard for accounting for stored carbon, so it is typically ignored and is not considered as part of embodied or whole life carbon assessments.

In 2025, we sponsored and joined the Technical Advisory Committee for a Grown in Britain–led project aimed at developing a certification scheme for biogenic stored carbon in harvested wood products. The initiative seeks to monetise the carbon stored within timber used in construction, helping to incentivise the uptake of biogenic materials. It brings together timber manufacturers, academic institutions, government departments, and tier one contractors under the Timber in Construction Roadmap framework. Version one of this new standard is expected to be published in 2026.

Lobslack Seed Processing Facility (below) is both a UKNZCBS pilot and a fine example of British forestry and construction industries working collaboratively. The £14.5m Forestry England project near Delamere Forest, Cheshire, uses Cross-Laminated Timber, glulam and UK-grown sustainably sourced timber, in a design targeting net zero carbon in operation through features such as solar PV, triple glazing, sustainable drainage and energy performance monitoring.