How we secured Part O overheating compliance for 260 Redrow homes without compromising their signature architecture.
Project Summary:
- Client: Redrow Homes
- Development: De Clare Gardens, Caerphilly, Wales (260 Dwellings)
- Service:
- Part O Overheating Compliance
- Dynamic Thermal Modelling (TM59)
- Outcome: 100% Compliance achieved with without costly redesign delays.
The Challenge: Part O Compliance
Introduced to mitigate the health risks of climate change and heatwaves, Part O of the Building Regulations has fundamentally changed how new homes are designed. Learn more here.
For Redrow’s 260-home De Clare Gardens development, achieving compliance presented a challenge. The site featured Redrow’s bespoke “G-series” house types, which are celebrated for their large, complex glazing arrangements.
If assessed using the standard, rigid “Simplified Method” for Part O, these highly glazed homes would have certainly failed. The default penalty would have been a forced reduction in window sizes, entirely compromising Redrow’s architectural vision and curb appeal.
Our Solution: TM59 Dynamic Thermal Modelling
Instead of relying on basic spreadsheet assumptions, we built highly detailed 3D thermal models of the complex house types. This allowed us to simulate the exact thermal performance of the homes hour-by-hour, tracking precise sun paths, shading profiles and ventilation rates over a full year.
The strategy involved:
- Bespoke Glazing Inputs: Using accurate G-values (solar transmittance) rather than punitive defaults.
- Targeted Interventions: Where specific units with high-risk solar orientations failed the initial TM59 criteria, we didn’t send Redrow back to the drawing board. Instead, we modelled localised mitigation strategies—such as specific shading devices and revised ventilation pathways—until a pass was achieved.
- Early-Stage Collaboration: By working closely with Redrow’s technical team from the outset, we ensured all proposed adaptations were highly buildable and cost-effective.
Dynamic Thermal modeling provides a powerful tool to ensure that the homes we built today are not only energy efficient but are also prepared to deal with the future challenges of changing climates. By using advanced software to allow for design flexibility, and the use of glazing properties and shading that is not used in the simplified overheating method.
Richard Millard, Senior sustainability Consultant at Building Energy Experts
The Result: 100% Part O Compliance, Zero Compromise
By applying expert analysis rather than blanket rules, we successfully navigated the complexities of the site.
- Architectural Integrity Saved: We achieved full Part O compliance across all 260 plots—including the heavily glazed G-series—without shrinking the windows.
- Clear Evidence for Building Control: We provided Redrow with robust, highly detailed TM59 reports, allowing them to confidently submit their evidence and secure approval without delays.
- Informed Decision-Making: Our proactive guidance allowed Redrow’s design team to finalise their house type designs and site layouts knowing the overheating risk was fully managed.
Client Testimonial
We’ve worked with Building Energy Experts to support Part O compliance across our developments and have been consistently impressed with their service. Their team is proactive, knowledgeable, and always on hand to provide clear guidance throughout the design and compliance process.
Their reports are thorough yet easy to digest, and their input has been instrumental in helping us meet regulatory requirements without compromising on design. The quality of their reporting and technical advice has made them a valuable partner to our team.
Sean Haplin, Technical Coordinator at Redrow Homes
Don’t let Part O ruin your elevations.
If you are planning a residential development with large glazing, complex shading or single-aspect apartments, the Simplified Method will likely fail you.
Contact us today to discover how our dynamic thermal modelling can protect your design and secure compliance.
