The UK’s largest net zero housing development has been confirmed for Penarth, South Wales — and Darren Evans is proud to be playing a central role in making it possible.
The Upper Cosmeston Farm masterplan will deliver 576 new homes, a primary school, and community facilities on the edge of Penarth. Backed by the Welsh Government and led by Barratt Developments, the project is being hailed as a landmark for sustainable housing.
The Challenge
Welsh Government made clear from the outset: this development would need to prove, contractually, that it could meet the highest standards of energy and carbon performance. Achieving “true net zero” across hundreds of homes at scale, and within financial and buildability constraints. This had never been attempted before in the UK.
Barratt Developments needed a trusted partner who could not only model performance but also provide the clarity, credibility, and assurance required to secure government approval.
Our Role
Darren Evans was invited to join the bid and design team, drawing on our proven track record of innovation with Barratt, including the Zed House, the UK’s first zero carbon future home demonstrator.
Our contribution has included:
- Energy & Carbon Modelling: Running sample dwellings in SAP and then modelling all house types in PHPP (Passive House Planning Package) to confirm the entire development can achieve true net zero.
- Technology Evaluation: Assessing the performance of different heating technologies, ensuring that the chosen ground source heat pump (GSHP) strategy could deliver genuine zero carbon outcomes.
- Design Integration: Working closely with Barratt, BUUK Infrastructure, and Eco2Solar to refine assumptions, adjust calculations, and provide the modelling foundation for the successful Welsh Government contract.
- Future Delivery: Continuing to support the project with construction specification advice, SAP & EPC services, and PHPP modelling across every dwelling to maintain confidence through design and build.
The Results
- True Net Zero Confirmed — both regulated and unregulated energy demand verified with contractual buffers, giving Welsh Government the assurance it required.
- Bid Success Secured — Darren Evans modelling and guidance contributed directly to Barratt’s successful appointment as developer.
- Future-Proofed Delivery — the modelling framework ensures smooth compliance with emerging standards such as Part O, while supporting Welsh Government’s broader goals of community value, social housing, and apprenticeships.
The Impact
The Upper Cosmeston Farm development is more than just a housing project. With half of the homes designated as affordable — including 219 for social rent — and community infrastructure such as a primary school, walking and cycling routes, and open space, it represents a new model for sustainable placemaking in Wales.
For Darren Evans Ltd, the project is the clearest expression yet of our mission: making sustainability an advantage.
“At Darren Evans, we believe sustainability should create legacies, not liabilities. Cosmeston is a landmark project — the largest net zero housing development in the UK — and we’re proud to play our part in making it possible. Our role has been to bring clarity to the complex, ensuring that Barratt and the Welsh Government had the technical assurance they needed to move forward with confidence. This project shows that when sustainability is done well, it stops being a burden and becomes an advantage for clients, communities, and future generations.” — Darren Evans, Managing Director, Darren Evans Ltd
Key Facts
- 576 new homes at Penarth, Vale of Glamorgan.
- 50% affordable housing, including 219 social rent homes.
- True net zero performance validated in PHPP.
- Largest project of its kind in the UK — and potentially Europe.
- Includes primary school, cycle routes, and open community spaces.
Next Steps
With surveys and agreements under way, construction is expected to begin within the next two years, led by BDW South Wales. Darren Evans Ltd will continue to provide technical guidance and assurance throughout delivery.
Closing Call to Action
This is the kind of trusted work Darren Evans Ltd delivers every day. If you’d like to see how we can support your flagship project with clarity, confidence, and credibility, get in touch.
Darren Evans – Founder