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New technology transformed this old Swiss building into a thrilling concrete eco home

The mountains of Switzerland are scattered with picture-perfect chalets with prettily carved wooden balconies and quaint pitched roofs. Among this rural landscape, concrete is a rarity. Older buildings are constructed from stone and timber and modern additions often employ a similar material palette. But a house on the edge of the town of Chamoson breaks this mould.

With the help of architect Laurent Savioz, Josyane and Michel Roduit have transformed a dilapidated farm building into a dynamic, yet contextual modern home. The house combines the existing traditional stone walls with a bold use of concrete. The result is a crisp, contemporary building that provides a modern twist on Swiss vernacular architecture.

The house stands proudly within a setting of soaring mountains, on the outskirts of the town in the south of Switzerland. The rural farm building was first constructed in 1814 but by 2003, when the Roduits acquired the house, it had slipped into a sad state of repair. Its sturdy limestone walls had survived relatively intact, but only part of the building was habitable. The roof leaked, and the timber cladding was weather-beaten beyond repair. ‘It was in a very, very poor state,’ says Michel. Luckily the Roduits, who lived in a neighbouring property, recognised the potential of the 380sqm building and bought it when Henri, the previous elderly owner, passed away.

Josyane and Michel are an active couple who like to ski in Verbier and hike and cycle in the surrounding Swiss countryside. With their children now grown up, but often wanting to visit, they decided to keep their old house for guests and transform the farm building into a home designed precisely for their needs. Josyane is an artist and wanted a bright and naturally lit studio and exhibition gallery, while both she and Michel craved a modern, energy-efficient building that would signal a radical departure from their previous, traditional chalet home.

They tracked down Swiss architect, Laurent Savioz having being impressed by a house that he had converted in the nearby village. Over the following year they had weekly meetings with Laurent, during which they formalised the design. ‘We were very demanding on Laurent’s time, we wanted to know about all the technical details,’ says Michel. ‘With a complex project like this, it’s important to choose an architect who is available on a daily basis and who will spend time discussing every aspect of your home.’

Laurent’s creative hands were slightly tied by the strict planning restrictions imposed on the site. The original walls had to be maintained and only three new large openings could be cut into the existing facade. The architect’s solution was to insert a concrete frame within the stone carcass of the building – to support the original structure but also allowing for reconfiguration of the interior.

For the most part the concrete remains hidden from view, except on the east- and west-facing sides of the building where it has been left exposed in place of the original timber cladding. Its crisp appearance at the deep window and door reveals creates a dynamic contrast with the worn and irregular limestone boulders. Here, as with the rest of the building, the attention to detail is impressive. By casting these exposed sections of concrete in moulds made from rough planks of wood, Laurent has evoked the appearance and the texture of the original timber. The exterior may now incorporate contemporary materials, but it pays homage to the traditional structure that it has replaced.

The juxtaposition of stone and raw concrete continues inside, where rooms cast from concrete have been slotted between three internal stone walls that remain untouched. By cutting apertures of various sizes into the partition walls, Laurent has created a free-flowing and energetic space, with daring floor heights and angles. On the ground floor there is a gallery where Josyane can display her artwork, as well as a sauna, wine cellar and utility room. From here, a concrete staircase leads to the first floor kitchen, bathroom, living/dining room and Josyane’s studio.

Finally, the mezzanine level provides space for a bedroom and an en-suite bathroom. ‘Josyane spends most of her time in her studio, but I like to wander throughout the house,’ says Michel. The concrete floors, walls and ceilings have been left exposed adorned only with the odd painting and bright orange cabinets in the kitchen and bedroom. ‘We both love concrete,’ says Michel. ‘It’s very versatile and we’ve been able to keep all of our old furniture, except for the sofa and a table.’

The Roduits are so pleased with the house, that there is absolutely nothing that they would change given the chance to start again. This is not only a tribute to the building’s appearance, but also to its performance as an energy-efficient and comfortable home. The house is built to the Swiss Minergie standard for sustainable construction, which is not a compulsory standard, but is widely accepted as a mark of ecologically responsible design. To reach this standard Laurent had to ensure that the building was efficiently insulated and airtight. The use of concrete was an essential strategy in achieving these aims. But instead of standard concrete, Laurent specified Misapor insulating concrete for the roof and the walls (see box, left). By adding a 30cm layer to the existing 60cm exterior walls he could dispense with any additional insulation material, while in the roof he added a 26cm layer of glass wool. His choice of Misapor concrete allowed him to build an incredibly well-insulated house with the use of minimal materials.

While all the windows have airtight aluminium frames and double-glazed panes, the larger openings are fitted with glass that reflects 80 per cent of solar radiation. This limits the amount of heat absorbed by the concrete interiors during the summer months, when temperatures could become uncomfortable, but allows in sufficient heat during the winter to help warm the home. ‘It’s great,’ says Michel. ‘The house is really comfortable all year round.’ Additional eco credentials include a heat recovery system, which naturally ventilates the house, two wood-burning stoves and 23sqm of solar panels on the roof that provide 35 per cent of the house’s energy needs.

But how has this very contemporary addition been received? ‘We’ve had a really positive reaction to the house from family and friends, and we’d love to start another conversion.’ says Michel. This building demonstrates how concrete can be used honestly and respectfully to not only save, but to improve historic homes.

Pull quotes

The crispness of the concrete creates a dynamic contrast with the stone

The architect has created a free-flowing, energetic space

‘we’ve had a really positive reaction to the house from friends and family’

eco choice?

Concrete usually gets a bad rap from environmentalists, and understandably so, but there are eco pros and cons.
The quarries from which the aggregate is taken can scar the landscape. Because quick delivery is crucial for ready-mix concrete, it goes by road, creating millions of lorry journeys per year. Making cement produces a lot of CO2 emissions, then the chemical process that occurs when concrete sets creates even more.
These effects can be somewhat mitigated by using a concrete made with pulverised fuel ash or ground granulated blast furnace slag. These are both waste products from power stations, and can be used to replace up to 50 per cent of the cement in concrete. Most ready-mix contractors offer this kind of aggregate – to search for a company near you, go to aggregain.org.uk. To find out where pulverised fuel ash actually comes from, the United Kingdom Quality Ash Association has this information on its website, ukqaa.org.uk.
To make your mix more environmentally friendly still, the aggregate could be old concrete, ground up and recycled.
Concrete is incredibly tough and long-lasting, so using it can increase a building’s lifespan.
Your concrete can also be used in a way that helps the environment. A concrete block wall can store about twice the heat of a plaster stud wall. This is called high thermal mass, and means concrete can work as a heat sink, warming up slowly during the day and then emitting heat in the cool of the night – or vice versa, in summer.
To find out more about the various applications of concrete and how it can be an eco choice, visit concrete.org.uk and sustainableconcrete.org.uk.

Foam Party

Misapor concrete (misapor.ch) is made with a recycled foamglass aggregate, providing a use for old bottles, window panes and other waste glass. Foamglass is manufactured by passing a gas through glass at very high temperatures, the gas then expands, producing a dense honeycomb structure, which traps air within the concrete. This means that despite being as strong and durable as conventional concrete, it is a much lighter material. The air pockets also improve its insulating properties, and it can be used for roofs and walls with no additional insulation. It can be cast on site or used for prefab panels, it’s suitable for interior and exterior surfaces, and can be polished smooth, left exposed or rendered and painted.