The objective of this design is to convert an existing four-unit housing block into an energy efficient, sustainable building while increasing the amount of habitable space in it. This new focus is established in a series of extensions that gives the project its name: Backpack Building.

The visual language of the extension enhances the unity of the block; it appears as one, although it is actually a composition of individual extensions to each housing unit. The added elements alternate, reaching into the private gardens while also linking the living and dining areas with the green space.

Our characteristic step to convert terraced houses that allow their occupants to maintain a twenty first century lifestyle as they grow older will be the signature of the project. This enhances the existing housing blocks by providing easily accessible floor space while also ensuring that each of the four units has an identifiable address.

A distinctive feature of the new master plan of Gentoo leaves the houses' original entrances on the east side facing a large pedestrian promenade, while parking and the street are located to the rear. The grim corridor through the centre of the building will be closed off, enabling future tenants to decide where to locate their main entrance, depending on personal preference and mobility.

An advantage of this layout is the accessibility of front and back gardens, providing diverse options as far as activating these spaces is concerned. We aim to generate 2 two-bedroom and 2 three-bedroom units. The two-bedroom units on the face sides have an 80 square metre gross internal area (GIA) while the threebedroom units in the centre have a 125 square metre GIA. The original division of the building remains, so that there is a ground floor entrance to each unit, where the living, kitchen and dining areas are located.

All units have direct access to a front and a back garden. The space formerly taken up by the central corridor will be integrated into the middle units, thus creating a more generous floor plan.

The exposed brick walls of the original structure - where not hidden by the backpack extensions - will be overclad entirely with a brick slip system. The cladding system comprises an insulated backing panel which comes pre-laminated with a vacuum-formed waterproof polystyrene skin, moulded to form a template of horizontal tracks which locate the brick slips. The aim is to provide a highly insulated façade, which, in conjunction with a high-quality insulated window system, creates an airtight and thermally efficient building.

The backpack extensions provide a second highly insulated skin for large parts of the original building.

They are constructed from prefabricated laminated timber walls and slabs and are craned into site to minimize construction time and to maximize accuracy and airtightness.

The prefabricated panels are insulated with two layers of hard fibre boards achieving an excellent thermal transmission coefficient while keeping the depth of these components to a minimum. The new extension is clad in untreated cedar boards with a buff-varnish coating; they are as durable as roughcast or stone walls and they require very little maintenance.

»Environmental technologies
We have avoided a high maintenance, complex approach, opting instead for established environmental technologies. We propose a groundwater heat pump to aid heating. We further propose solar collectors on the roof of the backpack extensions to help supply both hot water for general use and heating.

We have planned adequate space in the attic for the technical equipment of any system chosen. A rainwater storage tank is placed in the garden to help reduce treated water usage in the toilets and to sprinkle the lawn during the summer.

We project an energy saving of more then 10% over a 1-year period; however at this stage of the project, detailed confirmation of eco savings would be premature, as a budget is yet to be confirmed. All units are provided with allocated bike shelters to support non-motorised traffic and the floor plans are developed to Lifetime Home standards, giving special consideration to the needs and aspirations of older and disabled people. The entire construction will be Building Regulations and NHBC compliant. The proposed extensions and reconstructions are deliverable within realistic budget parameters and are fully warrantable to enable development.

© British Homes Awards |  Site design: LW design