Interiors: Simon and Annie Winstanley didn’t want their zero-carbon house on a Dumfriesshire hillside to stick out a mile; it had to be a subtle reponse to the surrounding countryside

WHEN Simon and Annie Winstanley found the perfect hillside on which to build their carbon-neutral family home, they were keen that it would be a subtle and simple response to the surrounding landscape, rather than an eco home intent on wearing its green hardware on its sleeve.

What emerged in 2010 from the west-facing slope in Dumfriesshire is the Houl, a streamlined, single-storey house designed by Simon as a contemporary take on the traditional Scottish longhouse. And this seamless combination of eco savvy and meticulously detailed contemporary design hasn’t gone unnoticed. The Houl has won a RIBA award, and got a special mention in Scotland’s Best Building Prize 2011.

Simon, who is something of a pioneer in low-energy house design in Scotland, had been preoccupied with the idea of creating a family home that was sustainable in its construction, low in energy consumption, with net-zero carbon emissions in all its energy use. An opportunity presented itself in 2007, when a 12-acre site owned by a local farmer became available.

Overlooking the River Ken valley, the site wasn’t without its challenges, as Simon explains. “The site is in an area that has a special status, which only allows properties to be built in the open countryside as long as they are part of a smallholding. It’s an unusual rule in planning. The area was depopulated and the principle was to try and repopulate the village and the area. My application was the first submission under this tightened policy and meant that I had to have an agricultural justification for the site as well as making a full planning application.”

Part of the agricultural justification identified keeping eight sheep on the land. Sheep were on the land before the house was built, and having them graze helps maintain the grassy hillside behind the house.

The planning process may have taken a little longer than expected, but the 15-month build by 3b Construction was fairly straightforward, despite the rocky terrain. A low-energy approach was adopted from the outset by re-using all excavated rock to create the track to the house.

The house shelters from the prevailing wind in a concave cranny on the exposed site. The main living accommodation, including lounge, kitchen, dining area, music room and two bedrooms, are arranged along the glazed west-facing façade, taking advantage of the wonderful views. Ancillary spaces, including a utility area, shower and bathrooms as well as a study/bedroom, are recessed to the rear.

The main entrance is on the sheltered north-east side of the house. The main roof seam, above the living accommodation, follows the line of the hillside and slopes up to meet the slightly lower rear roof. A strip of clerestory windows has been incorporated to allow morning sunlight to filter into the heart of the house.

Clad in cedar weatherboard, the Houl includes passive house standards of insulation in the walls and roof. The house is heated principally via solar gain from its high-performance triple-glazed Nordan Entec windows and glazed external doors.

Renewable mechanical systems include an air-source heat pump that powers the underfloor heating and hot water, and a whole-house heat-recovery ventilation system that brings in tempered fresh air. A Skystream 3.7 wind turbine, which was chosen for its elegance as well as its performance, also generates supplementary electricity in addition to the mains supply. “All the renewable systems are working fine,” admits Simon. “The only thing we have to do in terms of maintenance is take a Hoover to the filter of the heat-recovery system.”

Although the Houl can be considered as an ultra-low-energy house, Simon says, “Strictly speaking, this isn’t a true passive house. There are passive house standards of insulation in the walls, but a true passive house has a limit to glazing and I’ve gone for too much glazing because the view is so fantastic. The flipside is that I also get good solar gain, sometimes too much, which is why I designed the roof to overhang, offering some shade.”

Inside, rooms are pared down and unfussy, in keeping with the building’s overall design. Floors are oak and Kirkstone slate from a supplier in Cumbria. The beech kitchen units and island were designed by Simon and made by a local firm in Dumfries – “just using a sophisticated plywood, really”, he says.

Simon also designed the stove surround, one of the key focal points of the open-plan living area. “The actual inset stove is off-the-peg, but I designed the enclosure. It’s rendered blockwork with a solid steel plate top and acts as a log store, room-divider and place for the telly.”

The furnishings are simple and include a Patricia Urquiola Flo armchair; Philippe Starck Mister sofa and Hannes Wettstein Hola dining chairs, both from Cassina. Above the dining table is one of the few pendant lights in the house – sunlight and uplighters account for most of the building’s illumination – an AJ Royal Arne Jacobsen-designed light by Louis Poulsen. “It’s all about keeping it simple,” concludes Simon. “There’s deliberately not too much technology in the house. The main principle is that it’s very highly insulated, and I’ve taken a great deal of trouble to make the building airtight.

“In terms of the [eco] components, these are the top of the range, so they work well – quietly and efficiently. Performance-wise, it costs £10 a week to run – for everything. So you could say it’s all going to plan.”

Simon Winstanley Architects www.candwarch.co.uk