Slice House, runner-up for The Concrete Centre Sustainability Award 2005 and one of seven projects to win an RIBA Worldwide Award in the same year, demonstrates that a difficult building plot can be a driver for creative and imaginative architecture.
The site is a very narrow strip of urban space, measuring 3.5 x 40m, left over after the opening of a new road in Porto Alegra, Brazil. The architect, Proctor?Rihl, created the structural envelope of the house from reinforced concrete, with 150mm walls and floors, and 100mm ceilings. This has enabled a column-free environment without visual obstacles, which is important for such a narrow site. The house incorporates a number of quirky features, including a concrete desk, but the crowning glory has to be the small external plunge pool that opens off the terrace at upper-floor level. This has a fully glazed side that drops down into the living area below, allowing a view of swimmers and providing a path for the sun to shine into the building during the autumn and winter.
One of the client's requirements was for a design that avoided the need for air conditioning, which was no doubt influential in the decision to use concrete, with its high level of thermal mass. Internal surfaces have been left exposed, with a combination of painted walls, polished floor slabs and ceilings that are fair faced and unpainted. These provide excellent thermal linking between the concrete and the internal air, ensuring good temperature stabilisation during hot weather. Minimal openings were created in the west facade to avoid excessive solar gains.
The northern windows (equivalent of south in the UK) employ good solar shading in the form of overhangs, plus a louvred courtyard and the water in the transparent-sided swimming pool.
Sustainability issues have featured strongly in the design of Slice House. Clearly a lot of thought has gone into the passive cooling of the building. And the use of an awkward brownfield site has done much to minimise the environmental impact in terms of land use. The recycling of materials has also been a key feature of the project: the eucalyptus posts used to brace the concrete formwork were recycled at a local paper factory, and the wall forms were built in stages enabling less timber to be used. The best plywood and timber planking for forming concrete was reused in the roof trusses and to deck under the metal roofing, resulting in very little waste. Any wood that remained was reused by the builder on other projects. All these measures score well in terms of achieving lean construction and managing natural resources.
Slice House has now been occupied for over two years, and feedback from the delighted owner is testament to its success, which in many ways has been made all the sweeter by the somewhat unorthodox and risky nature of the project. Proctor? Rihl successfully took on a difficult challenge that included balancing good sustainable performance with inspirational living space.