There is nothing like building yourself a house to make you reflect on how you might have done things differently. That’s the experience of Fiona and Tom Robinson, who are both architects.

The couple completed their four-bedroom, two-and-a-half-storey house at Drymen in Stirlingshire six years ago, and the result is classically pleasing and understated yet stunning. The exterior is rough-cast traditional block — in keeping with local tradition — set in grounds of an acre-and-a-half.

The house would have cost about £250,000 to build, but the couple shaved a little off this by undertaking a large amount of the work themselves. They enjoy living in it but, as it was being completed, they came across the idea of passive housing — a building design movement that makes energy-efficiency a priority.

Now the Robinsons have had a radical rethink about their house — and wish they had done things differently.

They believe it could be more energy-efficient, right down to the choice of appliances — so efficient that it could be “passive”, that is needing minimal external heating sources.

“I would have much more insulation in the walls — about 350mm,” says Tom. “I would also have passive house windows, which are angled to capture sunlight and are extremely well insulated. I would also go for a heat-recovery system.

“Passive housing is really about creating a building that is precisely designed for the climate it’s in. Energy costs are going up, and it would be nice to build a house knowing you’re not exposed to that. You are virtually getting yourself away from having to spend a lot of your income on fuel bills.”

The couple currently heat their home with a high-efficiency gas boiler and bills come in at about £300 a year.

The idea of the Passivhaus originated in Germany in 1992. It is about adapting a house design so that it can heat itself through passive solar gain and body heat. In summer, the houses also self-cool with designs that maximise through breezes. Passive housing has taken off in Germany and Scandinavia, and can mean the elimination of heating bills.

The principle of passive housing often leads to some unusual buildings.

“Sometimes passive houses look as though they have been designed as machines capable of gathering sunlight during the cold periods of the winter,” says Tom. “They look as though the normal architectural rule book has been thrown out the window. ”

He is interested in combining aesthetic appeal with principles of efficiency. “So many things influence the look of buildings that if you leave it to pure science and make it all about perfecting the thermal envelope of a building, you end up with structures that are unfamiliar and find hard to like,” he says.

Inside, the family’s house is furnished in natural materials. In the Robinsons’ case, it was done in part to accommodate their 13-year-old son, Jamie, whose enthusiasm for rugby is hampered by a sensitivity to dust mites. Since moving into the house, there has been a marked improvement in his asthma.

The presence of an open fire in the drawing room may seem incongruous. But the family considers the fire a sustainable luxury because there is plenty of fallen timber nearby.

“As an exercise, we decided to see if a house such as this could be made to meet passive standards so have put it through our PassivHaus Planning Package software to see if it could be made to meet the standard,” says Tom. “The results were pleasing, as we found that the building form, orientation and proportions of glazed areas made it easy to adapt to achieve compliance.”

However, the costs of changing the window type, improving insulation and implementing the other changes look prohibitive.

But the Robinsons are getting a second chance nonetheless — they plan to build a holiday home in their garden using the passive house principles. They hope it will earn an Association of Environmentally Conscious Builders (AECB) gold standard — which is close to the passive house benchmark.

The Highland Housing Fair — an exhibition of architecturally innovative houses next year — is due to feature a passive house. So the technology is in place and there is precedent on the continent. Now the Robinsons are on the lookout for a forward-thinking client who wants such a home.

An alternative route is Weberhaus, a German firm with offices in Inverness, which is offering to build passive houses from as little as £150,000.

www.passivhuscentrum.se, www.weberhaus.co.uk; www.thomasrobinsonarchitects.co.uk

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