A stylish, sustainable Passivhaus in the depths of rural Somerset

Tucked away down a quiet country lane, Graham and Emily Bizley's self-designed house looks both entirely at home and somehow rather exotic, as if a little slice of Sweden or Switzerland had been mysteriously teleported into the depths of rural Somerset.

With its oak-clad exterior and wide-span roof, it is the kind of house that is common enough in northern Europe but not, for some reason, often seen over here, where builders continue to churn out little brick boxes year after year.

In fact, this is an even more unusual building than it might look, as it is a passive house - constructed using the principles of the Passivhaus building standard developed in the Nineties.

It combines advanced insulation, clever heat-exchange technology and careful orientation to avoid the need for heating even in the depths of a British winter. It might sound like magic, but the Passivhaus concept is based on sound science and years of testing - and it works.

Graham, an architect with his own practice, and Emily, an interior designer, bought the quarter-acre plot in 2010, when it was occupied by a Twenties bungalow made - in Graham's words - 'largely from asbestos and bits of string'. Funded by the sale of a house that Graham had built for himself on a tiny plot in Newington Green, north London, they began work on the site in January 2012 and moved into the externally completed house the following winter.

On the steep lower slopes of a thickly wooded hill that rises to 100 metres from the aptly named Somerset Levels, the house is more than twice the size of the former bungalow, with two floors rather than one, though its roofline is only slightly higher - an outcome achieved by digging the lower storey down into the heavy clay of the slope. The lane runs above and behind the house, which presents a low, almost windowless front to the road, with wide overhanging eaves that shelter a woodstore and parking space. What you cannot see from here is the view that opens up on the other side, as the land falls away. This layout has practical as well as aesthetic considerations: the house is orientated so its widest, highest aspect faces south west and south east to catch the warmth of the sun, while the back, facing north east, is dug into the ground to minimise heat loss on that side.

The first surprise is the front entrance, which has the thickness of a door to a bank vault. That is mainly to do with insulation, but like the triple-glazed windows in their extra-deep frames, it gives a subtle feeling of weight and quality. Inside is a small, oak-clad entrance hall, its roughly slatted ceiling intentionally low. From here, there is finally a glimpse of the outlook that gives the house its real wow factor. As Emily says, 'People delivering things always crane their necks round the corner to see it.'

The main rooms are on this upper floor, along with a spare room and shower room. The kitchen, with its high, sloping ceiling and huge picture windows, is the largest space in the house, clearly designed for family and entertaining. Clad in French oak planks, it is kitted out with a free-standing work bench, a mix of mid-century Danish chairs and a simple table that Graham made from Ikea trestles and a few floorboards, salvaged from the old bungalow and painted white. A balcony wraps round two sides and is sheltered by the overhanging roof.

A step leads up to a cosy, oak-lined sitting room, arranged around a wood-burning Normatherm stove, which is there largely to provide hot water during the winter, when the sun is too weak to power the solar-thermal panels on the roof. Graham's office is next door, visually connected to the kitchen by a steel internal window, which he can open, he jokes, 'when I want to shout for a cup of tea'.

Downstairs is Emily's office, looking out to the garden, the family bedrooms (they have two small children) and, dug back into the hill, the utility rooms, which contain a 1,000-litre hot-water tank and the heat-exchange system that silently circulates fresh air through the house. The main bedroom has views across the sheep-scattered Levels and a bathroom paved in the same local Blue Lias stone as the entrance hall. Like the rest of the house, it feels solid and rather swish, but as Graham says, 'Making a place feel luxurious is not about spending money on everything: it's about getting a few important details right.' Like the Passivhaus philosophy, it's an approach that deserves much wider adoption.

prewettbizley.com | emilybizley.co.uk