Transition by Design, in collaboration with Bioregional, Edgars, and Currie & Brown, has developed a pioneering evidence base and policy guidance to support the creation of a Zero Carbon Local Plan for South Oxfordshire and Vale of White Horse. This project represents a significant step forward in addressing the climate crisis by ensuring that new buildings in the region are designed and constructed to meet ambitious zero carbon targets, encompassing both operational and embodied carbon emissions.
Project Overview
The project involved detailed energy modelling and analysis of eight archetypal buildings—four domestic and four non-domestic—to assess how local planning policy can drive the transition to zero carbon. By testing a range of construction specifications, from current building regulations to industry-leading net zero standards, the study demonstrates the technical and economic feasibility of achieving zero carbon buildings.
A standout feature of this project is its inclusion of embodied carbon, which accounts for emissions from the production, transport, and assembly of building materials. This holistic approach ensures that the environmental impact of construction is minimised, alongside reducing operational energy use.
Key Findings
- Space Heating Demand (SHD):
- Current building regulations and the Future Homes Standard do not meet the proposed policy targets for space heating demand.
- Net zero operational energy and reduced embodied carbon variants achieve the targets, demonstrating technical feasibility.
- Retrofits outperform current and emerging building regulations, offering significant energy savings.
- Energy Use Intensity (EUI):
- The proposed EUI targets aim to create zero or near-zero carbon buildings, prioritising energy reduction over on-site energy production.
- Current building regulations fall short of EUI targets, while net zero operational energy variants comfortably meet them.
- Unregulated energy becomes a significant share of total EUI in zero carbon variants, highlighting the need for comprehensive energy modelling.
- Photovoltaic (PV) Sizing:
- A minimum PV target of 120 kWh/m²/year (projected building footprint) is proposed where matching PV to 100% of energy use is not feasible.
- Only the office archetype falls short of net zero with this PV target, demonstrating the importance of flexible policy design.
- Net Zero Operational Energy:
- Some non-domestic archetypes, such as offices, struggle to achieve net zero due to limited roof space relative to floor area.
- Retail and warehouse archetypes with high unregulated loads face challenges but can meet targets with flexible policy adjustments.
- Primary schools, with large roof areas, are well-positioned to achieve net zero operational energy.
- Embodied Carbon:
- Embodied carbon increases from Part L 2021 to net zero operational energy variants due to additional insulation and equipment.
- Reduced embodied carbon variants bring emissions down to reasonable levels while meeting energy targets.
- Retrofits demonstrate the lowest embodied carbon, emphasising the benefits of retaining and upgrading existing buildings.
- Design Constraints:
- Architectural form significantly impacts space heating demand and EUI performance.
- Policy should incentivise efficient building forms while allowing flexibility in material choices and rooftop design for PV integration.
- Retrofit Benefits:
- Retrofitting existing buildings reduces embodied carbon compared to new construction.
- Retrofit standards for airtightness outperform the Future Homes Standard, contributing to significant energy savings.
- Non-domestic archetypes are generally easier to retrofit than domestic ones, due to their construction type.
Conclusion
This comprehensive analysis provides a robust technical foundation for the proposed Joint Local Plan, demonstrating the feasibility of achieving zero carbon buildings. The findings highlight the importance of a balanced approach to energy efficiency, renewable energy generation, and embodied carbon reduction. By addressing both operational and embodied carbon, this project sets a new standard for sustainable development in the UK.
