Low‑Carbon Concrete and Retrofit Momentum Transform UK Built Environment

Welcome to Net Zero News, your daily briefing on the UK’s transition to a low‑carbon future.

In the latest developments in the built environment sector, construction firms and housing associations across the UK are advancing efforts to decarbonise buildings through low‑carbon materials, retrofit financing, and nature‑positive design.

Laing O’Rourke has mandated the exclusive use of low‑carbon concrete across all its new UK projects starting from 1 April 2023. This shift aims to accelerate progress towards net‑zero targets and assist clients in meeting sustainability goals through a lower‑carbon construction supply chain. Meanwhile, Willmott Dixon Interiors has completed a net‑zero carbon refurbishment of a 139,000 sq ft office in Birmingham city centre. The project achieved BREEAM Excellent and EPC A ratings, is WiredScore enabled, and targets a 5‑star NABERS rating and WELL Gold certification, delivering both environmental performance and social value through local procurement and training schemes.

On school buildings, Willmott Dixon has received approval for a £29m net‑zero carbon SEND school at Silverwood School in Wiltshire. The design includes biomass boilers and a large photovoltaic array, and forms part of the company’s “Now or Never” sustainability strategy, which commits all new buildings and major refurbishments to operational net‑zero by the end of 2030. Separately, in Wales, Willmott Dixon secured a Passivhaus primary school contract targeting multiple green credentials including Achieving Passivhaus, Building With Nature, and WELL standards. Features include green technologies like rain gardens and nature‑based surface water management.

In Oxfordshire, Willmott Dixon is also set to extend and redevelop Speedwell House into a 5,200m² net‑zero in operation office. This project supports the council’s move to modern net‑zero facilities and paves the way for regeneration of their former headquarters in Oxford’s city centre.

Housing associations are also scaling retrofit works. Riverside has committed to a £72m retrofit programme to improve energy efficiency in over 3,000 homes across regions like Liverpool, Halton, Carlisle, Middleton’s Langley estate, and London’s Enfield. The three‑year programme is supported by £36m of government funding under the Warm Homes: Social Housing Fund and match‑funded by the association. And SNG, formed by the merger of Sovereign and Network Homes, has secured a significant loan backed by a government guarantee to retrofit approximately 15,000 homes across the South of England, helping advance its sustainability strategy.

Amid these initiatives, industry stakeholders have raised concerns about current delivery rates and standards. The Social Housing Decarbonisation Fund Wave 2.1, which aimed to upgrade nearly 94,100 social homes, has completed just 27% of its target retrofits as of mid‑2025. Though successful projects have seen post‑retrofit EPC ratings rise from 2% to 99% achieving A to C, experts cite red tape, planning failures, and inequitable participation as barriers. Additionally, some contractors warn that PAS 2035 retrofit quality standards impose excessive compliance costs for simple projects, especially on measures like loft or cavity wall insulation.

What This Means:
This wave of low‑carbon material mandates, school and office retrofits, and large‑scale housing retrofit programmes indicates the built environment sector is beginning to align with net‑zero ambitions. The firm-wide adoption of low‑carbon concrete by Laing O’Rourke signals that material decarbonisation is moving from niche pilots to mainstream practice. Willmott Dixon’s net‑zero projects across education and office sectors illustrate how operational carbon reductions can be embedded into design and delivery, while delivering social value.

Housing association retrofit programmes supported by public funding and financial instruments demonstrate a growing funding ecosystem for large‑scale emissions reduction in the residential sector. Yet, the slower execution of government scheme targets and concerns over PAS standards underscore the need for streamlined processes, greater support for smaller providers, and proportionate regulation that balances quality with cost.

As the UK continues its path toward a low‑carbon built environment, these developments highlight both the progress and the bottlenecks that need addressing to deliver net‑zero outcomes at scale.

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