Princedale Road

Passivhaus retrofit

The first Victorian residential retrofit in the UK to be certified to Passivhaus standard, an initiative to address the challenge of how to reduce carbon emissions in existing housing stock.

Client: Octavia Housing
Location: London
Size: 114 sqm
Construction cost: £179,000

The project was won through a government competition entered in collaboration with Octavia Housing, Eight Associates, Ryder Strategy and Enhabit. In a post-occupancy comparison evaluation with a typical house, Princedale Road consumed 83% less energy.

As the house was in need of a significant upgrade, the approach was to remove all floor structures and design new doors and prototype windows. Insulation throughout is as a warm blanket all around using standard products and designed to eliminate cold bridges. Hot water is produced by means of three solar panels on the south facing roofscape. Internally is a unit combining MVHR, an exhaust air heat pump and hot water storage as well as an underground labyrinth that tempers incoming ventilation air beneath the footprint of the house.

Key interventions:

Existing structure retention: 100%
Insulation: IWI, floor and roof.
Windows: prototype triple glazed timber lookalike sash windows.
Ventilation: MVHR and air source heat pump combined and circular galvanised ducts.
Air-tightness: 0.33 m³/h.m²@50Pa.
Thermal bridge: new floor joists re-hung on steel beams resting in insulated pockets within party walls. Insulation boards pass uninterrupted between the new floor structure and the existing facade.
Energy demand: 63 kWh/m2/yr
Fossil fuel free