Pioneering Net Zero Carbon Construction Policy in Bath & North East Somerset: Evaluating the effectiveness of novel planning policies over time

In January 2023, Bath and North East Somerset Council (B&NES) introduced the UK’s first planning policies requiring all new buildings to have net zero operational emissions and limiting embodied emissions for larger developments. Coinciding with this, a collaboration was formed between University of Bath academics, planning and climate officers at B&NES, and other local organisations, which studied the impacts of, and reception to, these pioneering policies in the first six months following their introduction [1]. This 2023 pilot study was published in a previous report [2], and the current publication builds on the findings of the first.
This project evaluates the success of the policies two years on, establishing long-term trends, opportunities for refinement, and the national policy implications of this unique policy case study. This report provides the outcomes of this follow-on project, aiming to:

• Understand the effectiveness and experiences with the policy, with a comparison to the initial pilot study.
• Investigate how projects perform compared to their initial planning applications.
• Gather in-depth insights from a variety of applicants and stakeholders.

Incoming planning applications received over a 12-month period were analysed, and a questionnaire was sent to applicants to understand their views on the policy two years after its adoption. In total, 59 planning applications were reviewed, with 56 out of 59 submissions for minor residential buildings, meaning the homes need to be net-zero operationally. Only five responses to the questionnaire were received, representing a significantly lower response rate compared to the 2023 pilot study. Additionally, four interviews were conducted with participants from the 2023 study to capture, in more detail, the experiences of applicants working with the B&NES policy.

The rate of compliance and key design parameters, such as thermal performance and air tightness, were compared for the 2023 and 2025 studies to see if there have been any noticeable changes in submissions and the reasons for non-compliance.

This study has highlighted the need to follow projects through to completion after they receive planning to track the performance of real-world as-built thermal performance, air tightness and resulting energy use of new residential buildings in the region. Additionally, we make recommendations for clearer policy communication to applicants, refinement of the energy policy and an increase in ambition for the embodied carbon target values.