The Stack House is designed to fit the maximum single FutureForm module width of 4.2m and adopts a long, thin building form often associated with the traditional townhouse. The steel framed modules stack either side of the stair core in a split level section thereby minimising internal circulation and creating variety in levels and room heights.

To overcome the drawbacks of a long and narrow plan, the designer has introduced a lightwell in the centre of the plan. This serves as a core for daylight, ventilation and life throughout the house; some rooms open on to this vertical space while others borrow light. During summer months the rain sensing rooflight can slide open to promote stack ventilation and a connection with the outside. In winter heat collected at the top of the lightwell is recovered, exchanged with the incoming, pre-heated, fresh air and then distributed around the house. At night the insulated shutter retains heat.

Instead of the traditional integral garage (which usually becomes a store for junk), the design features a multi-use space which offers secure, covered parking and forms part of the entrance sequence into the house. This courtyard opens on to the internal lightwell to create a protected family/ play area, thereby extending the open plan space the full length of the house. An ‘adults’ lounge’ and a flexible home working/study space are situated on the first floor – both interacting with the lightwell.

At the top of the lightwell is the roof terrace, which acts like a traditional conservatory and as the heat recovery zone. It serves as a place to catch some sun or to listen to the sounds in the sky. This space contains a clothes drying space, negating the requirement for a tumble dryer.

The bedroom accommodation is flexible, and family bathroom or ensuites can be planned in several configurations. The home work space can also be converted to a bedroom. The lightwell is designed to accommodate a lift for access to upper floors. Top level bedrooms open into the roof space and there is a hidden sanctuary to ‘get away from the chaos’ and read a book, looking out onto the lightwell and sky above.

Technology

This house will permanently lower energy usage and, compared with contemporaneous similar dwellings, save more than 25 per cent of the carbon emissions, forever, before the addition of renewable technologies. Ridge-located horizontal axis wind generators, clear glass solar photovoltaic and solar thermal panels lower carbon emissions further.

The designers recognise that building sustainable homes is more than just reducing carbon emissions. It is also necessary to design, construct and use homes in a way that minimises other environmental impacts, such as water, waste, and materials used.

The energy input for heat in the house is less than 0.5kW as a maximum in winter. Overall, the designers estimate 450kWh/annum being used for heating - less than 20 per cent of similar houses. The designers have specifically selected high COP air source heat pumps (ASHPs) as the primary heating and hot water source, because they are energy efficient, environmentally clean and a renewable resource. ASHPs are also able to use promulgated benign, less-expensive electricity.

The designers have planned for the whole house to be supplied with 'green' electricity, produced from sources that do not cause negative impacts on the environment, to further increase its sustainability credentials. The 'green energy certification scheme' uses renewable energy, so negligible CO2 is produced in the process.

The carbon footprint of the house is extemporary, but achievable with known technology. The house will achieve level 6 of the Code for Sustainable Homes. With the future code targets mapped out and 2016 fast approaching there is no reason to aim any lower.

Adaptability

The stacked modules lend themselves to alternative house configuration from two storey city pads to three storey family houses and a four storey ‘generation’ house. They can cater for a variety of households and their changing needs.

In terraced or semi-detached layouts, the arrangements introduce assorted public and semi-public areas, creating diversity and community.

The form of the roof and skin provide a clear domestic/residential identity, like the strong repetitive bay widows of nineteenth century townhouses. The skin is sheathed in recycled tyre rubber cladding and provides a neutral framework to develop street scenes encompassing regional variations and local materials.

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