My wife and I have now lived in the completed Wyndmyln House for over three years, we are fossil fuel free, running both house and (electric) car on sun and wind. I can now have fun with visitors who on entering often say ‘It’s lovely and warm, how do you heat the house’? to which I reply “That is the wrong question, the correct question is ‘How do you stop losing heat'”. The answer to the correct question is threefold; massive insulation all round; airtight construction with heat-exchange ventilation (not easy with masonry construction) and, (the bit timber frame houses miss), lots of internal thermal capacity. There are also numerous other refinements in this eco-design but those three are the essence.
Our 2.5kW wind turbine and 3kW of photo-voltaic panels generate some 7,000 kW hrs of power, much of which we use, and we import from Good Energy some 5,000 in the year. This runs the house and some 10,000 miles of car travel (with occasional free charging away from base). We have recently installed an ‘Island Grid’ so the house now runs off batteries and we will use more of our generated power and import less. There is a 3 sq.m. solar tube array for hot water and crucially, a South-facing, lean-to, double-glazed conservatory – our main heater. Even in February on a sunny day it gets up to 30c and then heats the house through high-level windows and a door. So we only need backup heating in December and January when the sun is low and, depending on the weather, part of November and February. Our backup is a large masonry stove, essentially a wood-burning storage heater. A Finnish design built by Stovemasons, it is the original ‘central heating’ literally in the centre of the house straddling the main living space and lounge. A load of 15kg hardwood logs, burnt at full ventilation, runs through a complex maze of channels dumping heat into the fabric. After a 4 hour burn it releases heat slowly for 24 hours. A ton of logs does the Winter which we supplement with small-wood and kindling from our own willow coppice. So the SAP rating of ‘A’ scoring over 100 for both energy and carbon is about right.