The UK’s first Net Zero Carbon planning policy delivers strong compliance at the planning stage, but the completed properties risk falling short without clearer guidance and tighter checks.
In an analysis of every planning application to Bath and North East Somerset (B&NES) council between May 2024 and June 2025 (59 applications, representing 683 new homes), researchers from the Department of Architecture and Civil Engineering at the University of Bath were able to evaluate the successes of the policies and called for improvements to reach sustainability targets.
Dr Will Hawkins, Lecturer in Structural Engineering Design and the study’s principal investigator, said: “The policy is clearly driving a rapid uptake of energy-efficient technologies and renewable energy generation whilst accelerating local skills and knowledge, although we still don’t yet know to what extent this will translate into real emissions reductions.”
Addressing operational and embodied carbon
Introduced in January 2023, the policy goes beyond UK Building Regulations, tackling the day-to-day emissions of heating, powering and cooling buildings, as well as ‘embodied’ carbon emissions involved in the buildings’ materials and construction.
Dr Hawkins continued: “Collaborating with B&NES council offers a unique opportunity on our doorstep, allowing us to study how regulation can drive decarbonisation in the built environment.”
An initial review of the first six months of the policies’ implementation showed a marked change in submitted designs, which had a dramatic impact on the anticipated energy performance of the proposed buildings. Two years later, researchers continued their study, exploring long-term trends and identifying opportunities for refinement and national implications of the unique policy case study.
The findings highlighted the feasibility of the policy, reporting a high level of compliance with policy requirements throughout the reviewed planning applications. No planning applications were rejected under the new policy, and the potential performance of proposed buildings improved dramatically.
In addition, researchers noted designers developing their own policy-compliant specification for new buildings in Bath and North East Somerset, suggesting the policy is reshaping local design practices and raising sustainability standards.
The report also highlighted areas for policy improvement. Draughty buildings require more energy to heat, undermining sustainability targets, and the study indicated a potential gap between planning-stage air-tightness targets and as-built performance. The researchers suggest post-construction testing, clearer guidance for designers, and improved training for construction workers could ensure proposed air-tightness targets are met; however, due to the lengthy process of planning, design and construction, examples of completed policy-compliant buildings are still rare.
From design to real-world performance
The policies require that larger projects also measure and limit the embodied carbon associated with materials and construction, which is an increasingly significant issue. For larger-scale projects, they found the current target of 900 kgCO2e/m2 is easily achievable and should be lowered to drive change. The team noted these projects are yet to submit as-built embodied carbon assessments, and the gap between design and reality remains uncertain.
Councillor Matt McCabe, Cabinet Member for Built Environment, Housing and Sustainable Development, said: “Bath & North East Somerset Council was the first Local Planning Authority (LPA) in England to have an adopted Local Plan policy requiring a net zero energy balance for new housing. I am pleased that taking this groundbreaking approach is driving energy-efficiency improvements and renewable energy generation, and that we are already seeing direct benefits across our area.”
Moving forward, researchers suggest that refining the policy to make instructions around documentation clearer could further boost compliance with the policy, while the cap on embodied carbon targets could be lowered to increase carbon savings in larger developments.
The progressive B&NES policies demonstrate that legislation is effective in accelerating change in an often slow-moving industry, and show it is possible to accommodate ambitious sustainability targets. This suggests that more rigorous national building regulations around sustainability could have a significant impact on the UK’s carbon emissions from construction.