Balham, Wandsworth, South West London

Design and installation of first prototype of EWi PRO eaves and verge system to a one off deep retrofit to an Edwardian terrace house aiming to achieve 80% CO2 reduction


Project Brief…


This project was carried out under the Technology Strategy Board’s Retrofit for the Future programme. Eligibility for funding rested on 80% CO2 reduction and the development of innovations aimed at breaking down barriers to retrofit.

The whole house plan developed by Prewett Bizley architects included super insulation, triple glazing, air tightness down to 1.1m3/m2hr and ventilation with heat recovery. The insulation strategy depended, a large degree to the installation of external wall insulation to the rear of the house, and this raised the awkward question of how to treat the eaves and verge at these interfaces. The innovation that was subsequently developed dealt with the 5 main challenges identified at that time:

• Weather tightness
• Minimising cold bridging and condensation risk internally
• Minimising additional heat loss
• Future proofing and maintaining ventilation to the loft space
• Visual elegance

The original prototype was designed as a modular system with the aim of eventual commercialisation as a standard product and consequently EWi PRO was formed.

"Remarkably for a prototype system the installation of the original system went very well. The building team fitted it within a day. The system has now been in place for 3 years and still looks and works as well as on day 1." ~ Robert Prewett - Prewett Bizley architects - Director