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Refurbishment Project Award

Number 20 Lena Gardens, London

20 Lena Gardens BPA 2013 Winner

Number 20 Lena Gardens in West London was a Victorian mid-terrace with solid brick walls, a leaky structure and single glazing.

The client demonstrated a very clear commitment to ‘deep’ sustainability and was interested in using the house both as a pilot project and as a case study for the application of sustainable retrofit techniques.

The refurbishment goals were: to maximise use of natural resources within the site’s limited footprint (80m2), to bring the input of external energy sources to a realistic minimum; very high levels of internal comfort; use of Passivhaus design principles and certification; use of recycled and low-impact materials wherever possible; and commissioning, monitoring and post-occupancy evaluation. A holistic design approach focused on fabric energy consumption, tight project management and integration of highly efficient services.

The building was super-insulated, with a double-skin insulation strategy providing U-values of 0.1W/mK on external walls and 0.3W/mK on party walls.

The design team and lead contractor were awarded grant funding by the Technology Strategy Board to develop triple-glazed, highly efficient, sealed, sash-type windows with a tilt-and-turn opening mechanism.

A full ventilation system with heat recovery was installed, designed to be used in conjunction with natural ventilation in summer. Solar thermal panels provided 60% of hot-water requirements and a 1.2kWp solar PV system was installed. A green roof provides biodiversity and insulation, while rainwater capture minimises runoff and substitutes potable water for irrigation. The retrofitiincreased usable space of the building from 195m2 to 235m2. Read more about 20 Lena Gardens in our case studies section.

Highly Commended

Wolvercote Road, Thamesmead Estate, London
Fraser Brown MacKenna Architects

A whole house refurbishment that combines existing low carbon technologies with new products. Read more about this project in our case studies section.


  • Bristol Old Vic, Bristol – Hoare Lea
  • Woolgate Exchange, London – Ove Arup & Partners International / Portigon Financial Services
  • The Co-operative Food Store, Piccadilly Gardens, Manchester – The Co-operative Group
  • Vaillant Group HQ, Belper, Derbyshire – Vaillant