Supporting Cotswold Homes’ South Gloucestershire planning application with a sustainability statement.
We provide Cotswold Homes, a leading housing developer in South Gloucestershire, Somerset and Wiltshire, with the majority of their Sustainability and Energy Statements. In this case study, we produced one for their Engine Common development in South Gloucestershire. The sustainability statement report supported Cotswold Homes’ planning application by demonstrating compliance with local policy and delivering measurable carbon emission reductions across the site.
The Challenge: Sustainability Statement
The Engine Common development consists of 20 new dwellings. South Gloucestershire Council planning requires major residential developments (defined as residential development comprising 10 or more dwellings, or development comprising over 1000m2 of floor space) to include the submission of energy information in the form of a Sustainable Energy Statement or as part of a Design and Access Statement. For major residential development proposals on greenfield sites, policy PSP6 has an additional requirement to reduce residual regulated and unregulated CO₂ emissions by at least 20% via the use of renewable and/or low carbon energy generation sources on or near the site.
To meet these requirements, Cotswold Homes needed a strategic approach to demonstrating compliance with the local planning policies while optimising energy efficiency and sustainability measures – that’s where our technical expertise came in.
Our Approach
We assessed the development using the energy hierarchy:
- Be Lean – Reduced energy demand through high-performance building fabric and efficient design, exceeding the minimum U-values required by Approved Document L.
- Be Clean – Evaluated energy supply strategies and potential district heat network connections.
- Be Green – Identified viable renewable technologies, selecting air source heat pumps (ASHP) and solar PV systems for integration.
To achieve compliance, we conducted SAP calculations and energy modelling in line with Part L (Volume 1, 2021) of the Building Regulations. The strategy incorporated:
- High-efficiency insulation (walls: 0.18 W/m²K, roof: 0.10 W/m²K, floors: 0.12 W/m²K)
- Air permeability below 5 m³/hr/m² to enhance airtightness
- Solar PV installations across all dwellings to meet renewable energy targets
- Air source heat pumps for efficient heating and hot water provision
Key Insights
- Initial SAP modelling revealed high baseline emissions, largely due to the assumption of traditional gas boilers.
- Our analysis showed that fabric improvements alone would achieve a modest CO₂ reduction of 4.54% against the baseline.
- A renewable feasibility assessment confirmed that ASHP and solar PV were the most practical and impactful technologies for this site
- The renewable strategy was carefully balanced to optimise available roof space for PV array positioning and maximise CO₂ savings.
Revisions and Improvements
Throughout the project, updates were made to enhance energy efficiency and align with evolving planning requirements. Initially assessed for 19 dwellings, the final strategy was refined for 20 dwellings, leading to recalibrated SAP calculations and a more detailed renewable energy implementation plan.
These updates resulted in a 59.63% overall CO₂ reduction (regulated + unregulated) and an optimised solar PV strategy with a total array size of 37.61 kWp. Further improvements to air permeability standards and water efficiency measures strengthened the development’s sustainability credentials and reinforced compliance with the planning requirements.
The Results
- Up to 4.54% CO₂ reduction achieved through a fabric-first approach and energy efficiency improvements
- An additional 77.62% reduction in regulated CO₂ emissions achieved with on-site renewables, including air source heat pumps and solar PV on every plot
- 59.63% overall CO₂ reduction against Building Regulations across the development (regulated + unregulated emissions)
- 25,802 kg CO₂ saved compared to the baseline regulated emissions
- Energy demand reduced from 181,575 kWh to 82,260 kWh after the integration of renewables
- Full compliance with South Gloucestershire Council’s sustainability planning policies (PSP6, CS1(8), CS3, CS4), which you can read more on here.
Through expert analysis and a strategic energy approach, we helped Cotswold Homes exceed South Gloucestershire planning requirements. Early-stage SAP modelling and renewable feasibility checks ensured the development would meet key performance thresholds. The final strategy combined fabric-first efficiency measures with the right renewables (in this case ASHPs and solar PV systems on every plot), resulting in a total CO₂ reduction of 59.63% across the site — well above the 20% minimum required under Policy PSP6 for greenfield developments.
Client Testimonial
Building Energy Experts produced a Sustainability & Energy Statement to support our planning application for 20 homes in Engine Common. They worked with our technical team to identify measures that would help energy savings across the development reduce residual carbon emissions. Despite the technical nature of the topic, the report was clear and concise and well received by the Council’s climate officers. I would happily recommend the team to other developers.
Ashley Grant, Planning Manager at Cotswold Homes
What’s Next?
This case study highlights the value of proactive energy planning. Close collaboration between our consultants and Cotswold Homes’ technical team ensured that design, performance, and planning targets were aligned — delivering compliance, efficiency, and long-term sustainability.
Are you planning a development? Get in touch today to ensure compliance with local planning regulations and maximise your project’s sustainability.
