Responsibilities on the project: Architect

Site Completion: April 2010

Contract Sum: £330,000.00

Gross Floor Area: 61.0m2

The clients for this project appointed BBM to design an eco-refurbishment of an existing 1930’s built bungalow with a large extension and new garage. The site is on the outskirts of a small village just north of the South Downs between Arundel and Pulborough.

Although a complete rebuild was considered, the existing roof was in good condition and the outer walls would form a useful thermal mass in any new house design. It was also felt that by retaining more of the existing, the Planning Department would receive proposals more positively, particularly noting the site was in a designated Area of Outstanding Natural Beauty.

There was no mains gas supply at site and so heating bills were a primary concern for the clients and a key driver in the design deliberations. The adopted strategy was to create a high level of thermal insulation around the existing and new enclosures, incorporate a pair of high efficiency solar thermal panels working in collaboration with a solid wood boiler. Initially the scheme included for a small 4KW unit which suited the Client’s request for a ‘front of house’ boiler and which could provide a focal point in the Living Room. Further analysis suggested that it would require a very onerous regime in stoking the fuel box. Thus a 15KW unit was incorporated into the scheme which required it’s own plant room and a massive 1500 litre buffer tank / thermal store.

Roof and wall insulation use predominantly materials from renewable resources such as cotton and hemp batts for the roof and wood cellulose batts for the walls. Cavity bead insulation was blown into the existing brick cavities.

Large areas of the house are finished with a polished and waxed concrete screed. The finish is like a monolithic stone slab and yet has a subtle resilience under foot due to the floor insulation below. The screed performs an invaluable role of ironing out unwanted fluctuations of internal air temperature. Other areas are finished with quarry tiles or engineered floor boarding with laminated ash. The latter is complimented by the client’s choice of wood for the door frames.

A largely glazed south elevation with sliding folding doors acts as solarium to the main living spaces of the house and provides useful ambient solar gains during the colder months. Excellent levels of cross ventilation and high thermal mass mitigates against overheating during hot weather.

The dominant roof form of the old house was mirrored over the new extension. A wide flat roof section divides the two which incorporates a large light canon over the kitchen area. The client was keen that the interior spaces should make use of the roof volumes and cranked beams were introduced into the design to prop both the old and newly constructed pitched roofs.

External works included forming new soakaway runs for the rainwater and a new driveway incorporating permeable gravel filled ground reinforcement.

Eco-Retrofit, Residential