Eco living: retrofitting a period home "We never wanted it to be like that," says John, an engineer and trained physicist. When we started house hunting, the rented home we were living in was damp and expensive to heat and we were absolutely sure we didn't want to live in another house like that, especially as we had a baby on the way. The problem, common to many young couples, was that they couldn't afford all the items on their wish list. They needed to be near a train station for work, and, keen on growing their own vegetables, they wanted a decent sized garden. It can still be a daunting task, however, and there are a dizzying array of materials and methods to consider. John says that it helped being a physicist and that there were times he would have given up. I am comfortable with assessing the thermal conductivity of materials and I know that heat will take the path of least resistance, so if you block one exit route with an insulated wall, it will look for another means of escape. But with a house more than 100 years old, at times the job was quite complicated and I spent a lot of time researching every possible risk to interfering with the building fabric. Over three years, John and Claire have installed both external and cavity wall insulation - the latter using the latest technology of graphite-covered polystyrene balls which perform much better than blown mineral fibre - as well as heat recovery ventilation and a "warm" porch to act as a buffer zone between indoors and out. They have reduced their energy bills by more than 60 per cent during that time. One of the best £500 I spent was to take out a redundant back door and in the gap build a cavity wall up to the height of the windows and install a triple-glazed window above that. It was only 40 bricks, 10 breeze blocks and a window but we reduced the heat loss over that area enormously. It made a huge difference to comfort and reduction in draughts," says John. He now wants to share what he has learnt with other people considering retrofitting their period homes. He has joined the SuperHomes network, a nationwide body of home owners who every March and September open their doors to strangers to spread the word about energy efficiency. From just a handful of SuperHomers three years ago, there are now 160 and rising. "We have no products to push and no policy to promote, and we can be honest about the drawbacks as well as enthusiastic about what works," says Norman Beddington, another SuperHomer who lives in an Edwardian semi in Haringey, north London. We started improving the house in 2009 and there has been a noticeable increase in the numbers of builders who know what we're talking about when we mention rainwater harvesting or low-E glass. It can be daunting, when first embarking on a retrofit project, especially if the house is an old one, but hopefully there are enough of us around to offer advice to anyone who is thinking about making their period home energy efficient. John and Claire's home and Norman Beddington's will be open during September as part of SuperHomes.