Morrish Homes has launched the first net zero ready homes at Nansledan, the Duchy of Cornwall’s award-winning extension to Newquay. Designed to support the long-term vision of a greener, more sustainable community, the two EPC A-rated semi-detached houses demonstrate how volume housebuilding can meaningfully reduce carbon impact.
The ambition was clear. Lower upfront embodied carbon, exceed current Building Regulations Part L, eliminate fossil fuels and integrate renewable technologies without compromising buildability or programme.
Reducing Upfront Embodied Carbon
A central objective of the project was to minimise embodied carbon from the outset. Key design decisions avoided traditional high carbon construction methods and replaced them with lower impact alternatives.
The use of direct fix cladding and render on carrier board removed the need for a masonry outer skin. A suspended timber ground floor replaced beam and block construction, significantly reducing concrete use.
The timber frame structure, including the ground floor and roof, was insulated with hemp. Hemp sequesters carbon while growing and is manufactured in the UK from local crops, supporting domestic supply chains while reducing transport emissions.
The combined timber frame and insulation system sequesters approximately 30 tonnes of CO₂e within the building fabric.
Fabric Performance and Airtightness
The homes were designed and built to exceed current Part L requirements, incorporating passive house levels of airtightness and high insulation standards.
Key fabric performance includes:
- External Walls – Bio Twin Wall system, U-value 0.13 W/m²K
- Ground Floor – Suspended timber floor with metal web joists, U-value 0.12 W/m²K
- Intermediate Floor – Suspended timber construction with metal web joists
- Roof – Trussed rafters, U-value 0.10 W/m²K
- Fire Rating – REI60 from inside to out
- Predicted Design Life – 60+ years
The result is a highly efficient thermal envelope that reduces energy demand before active systems are introduced.
All-Electric, Low Carbon Operation
The homes operate entirely on low carbon electricity, with no gas connection. As the national grid continues to decarbonise, operational emissions reduce further over time.
- Carbon reduction technologies and renewable systems include:
- Air source heat pump with A+++ energy performance rating
- 4.98 kWp solar PV array per home
- 11.5 kW battery storage, providing approximately 70 percent annual energy self-sufficiency
- Mechanical ventilation with heat recovery to improve air quality and reduce wasted heat
- Smart home hub to optimise low carbon technologies in response to energy pricing
- EV charging provision
The predicted Energy Performance Certificate rating is Band A with a score of 97. SAP modelling demonstrates an A rating with a score of 101, reflecting very low predicted carbon emissions in operation.
Delivered with Programme Certainty
The timber frame structure was manufactured, supplied and installed within a tightly managed programme.
Project data:
- Timber frame start on site – 10 February 2025
- Timber frame completion – 4 April 2025
- Number of working days – 35
- Gross internal floor area – 200 m²
- Architect – LHC Design
- Client and main contractor – Morrish Homes
- Hemp insulation supplier – GRWN Group
- Airtight flooring supplier – Medite Smartply
- Warranty provider – NHBC
- CAD software – Autodesk Revit
Services Delivered by Sydenhams Timber Engineering
Sydenhams Timber Engineering provided a fully integrated timber frame solution, including:
- Timber frame superstructure manufacture, supply and installation
- Revit modelling and structural calculations
- Supply and installation of hemp insulation
- Supply and installation of airtightness membranes and tapes
- Airtight flooring at ground and intermediate levels
- Service battens to external walls and first floor ceiling
- Installation of windows and external doors
- Supply and installation of fascias and soffits
- Mechanical lifting and cranage
- Energy assessment services including SAP calculations, EPC production under Part L, U-value calculations, PSI modelling, overheating risk analysis under Part O, PHPP modelling, carbon calculations and airtightness testing
These net zero ready homes at Nansledan demonstrate that reducing embodied carbon, achieving passive house levels of performance and integrating renewable technologies can be delivered within a mainstream residential development context through the Bio Twin Wall system.
