Major Retrofit Challenges and Innovations in UK Built Environment in 2025

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

A wide range of developments across the UK’s built environment sector in 2025 reveals both serious retrofit challenges and promising innovations pushing the net-zero agenda.

A damning National Audit Office report has revealed that almost all homes retrofitted under the Energy Company Obligation scheme suffer from major defects. According to the investigation, 98 per cent of external wall insulation installations affecting between 22,000 and 23,000 homes require remediation, with six per cent posing immediate health and safety risks including damp, mould or inadequate ventilation. Nearly a third of internal wall insulation installations 29 per cent are defective, and two per cent pose serious risks. As of September 2025, only eight per cent of external and ten per cent of internal installations had been remediated. The report highlights systemic failures in governance, weak oversight and possible fraud, estimating between £56 million and £165 million may have been wrongly claimed for unfinished or substandard work. Remediation for affected properties could range from £5,000 to £18,000 for external work and £250 to £6,000 for internal though some cases involving serious damp or structural damage have cost homeowners over £250,000. The NAO emphasises that the Department for Energy Security and Net Zero must ensure businesses address these failings urgently.

Meanwhile, another government-backed initiative, the Social Housing Decarbonisation Fund Wave 2.1, has substantially underdelivered. Launched in September 2022 to retrofit 94,096 social homes across England, the fund has only delivered 25,009 retrofits just 27 per cent of its target as of June 2025. However, where works were completed, energy performance improved dramatically, with homes rated A to C soaring from just two per cent before upgrades to 99 per cent afterwards. Industry experts attribute underperformance to procurement red tape, flawed initial designs, rising costs, limited participation from small housing associations and uneven regional uptake, with London accounting for just six per cent of completed retrofits despite having the largest socially rented housing stock.

On a more positive note, housing associations are stepping up retrofit efforts. In a significant development, a housing association has committed £72 million to a retrofit programme targeting 3,064 homes across Liverpool, Halton, Carlisle, Middleton’s Langley estate and Enfield in London. Half of this funding comes from the government’s Warm Homes: Social Housing Fund Wave 3, with the association matching the remainder. The three-year plan aims to combine warmer, more affordable homes with improved health outcomes and reduced environmental impact. The same provider previously delivered over 1,000 upgrades under Wave 2.1 across similar areas.

In parallel, the Future Homes Hub is pushing forward with nature-focused design strategies, expanding its ‘Homes for Nature’ initiative to include apartments. This update adds recommendations for high-rise residential developments such as nest bricks, hedgehog highways, pollinator planting and sustainable drainage systems to integrate biodiversity measures into apartments. Launched in September 2024, the voluntary commitment has attracted 28 homebuilders representing over 100,000 new homes annually, resulting in 300,000 nesting bricks or boxes to support urban wildlife through to 2030. These measures are also explicitly supported by Planning Policy Guidance on the Natural Environment. Innovation in building standards is also advancing. The UK Net Zero Carbon Buildings Standard is introducing a new “on track” validity check at Practical Completion to boost confidence and uptake providing early assurance that a building could meet the standard, subject to third-party verification. The full Version 1 of the standard is set to launch in winter 2025/26 following pilot testing and stakeholder feedback.

Willmott Dixon has delivered a substantial built-environment success story, completing the back-to-frame refurbishment of 19 Cornwall Street in Birmingham. Spanning 139,000 square feet over seven floors, the flexible, SMART-enabled office now meets net-zero carbon standards, making it one of the city’s most environmentally sustainable office buildings. The company is also advancing other net-zero construction initiatives, including a new ‘net-zero in operation’ headquarters for Oxfordshire County Council at Speedwell House, due in 2027, and further developments across the public sector.

What this means:
The built environment sector in the UK is at a critical inflection point. The shortcomings of retrofit programmes marred by quality issues, fraud risks and slow delivery highlight the urgent need for more robust oversight, streamlined processes and accountability. While retrofit efforts underperform, standalone housing associations and private contractors are delivering meaningful improvements, indicating the importance of targeted investment, strong project leadership and public–private collaboration.

At the same time, policy innovation, exemplified by biodiversity integration in home design, the new net-zero buildings standard, and adoption of sustainable, SMART technologies, signals a more sustainable trajectory. These efforts, however, must be scaled rapidly and paired with effective delivery systems to ensure that the benefits of net-zero retrofit and construction reach communities at speed and scale.

Upcoming Events:
Net Zero Scotland Projects Conference -16 June 2026, Edinburgh

Net Zero Nations Projects Conference – 6 October 2026, Westminster

Do you have technologies, innovations or solutions that can help public-sector net-zero projects? Email: lee@net-zero.scot