We hope that we won’t have to heat the Westacre house at all. And if we do, the thermal solar panels should cover most of it.
If all our insulation efforts, and the money we spent on high quality triple glazed windows, work out as intended, our house should be snug throughout the year.
A 16 cm layer of insulation on the outside of the walls, combined with the air tightness we hope to achieve, should cut out any draughts. That should keep all the warmth we generate from cooking, running appliances, and our body heat, inside the house.
Air tightness is great for that, but of course we also need to breathe. We will have to pump fresh air into the house and duct it to different rooms. The air will go through a heat exchanger, sharing the heat of the stale air going out with the cold air coming in. Our heat loss overall should be minimal.
It’s no guarantee that we’ll be warm enough though. We’ll need to live in the completely insulated house over one winter to work out exactly how much heating is needed.
If we do need to heat the living areas, we intend to do that with hot water from thermal solar panels on the roof. The hot water they generate will go into a heat store, basically a big insulated tank of water that can be pumped around the house when needed. We intend to use it for washing and bathing. And for any heating we need on cold days.
The tricky part, of course, is that when you need heating most, on cold winter days, the solar hot water panels are going to be the least effective. If we find ourselves feeling cold in winter, we’ll use a wood burning stove as extra heating. A stove with a back boiler will also be able to generate more hot water if we need it.
Consequently, we’re building a bit of redundancy into the house. We’re putting pipes for under floor heating into the concrete layer of our downstairs floor in case we need them. We’ll wait and see if we need a wood stove with a back boiler, and how big it needs to be.
And we’re keeping our eye out for free wood, like the dead alder trees Alex’s dad had removed from behind his house. It took us a fair while to chop them up, transport our share to Westacre, and pile them under the leylandii where they will have to season for a couple of years. We are also growing hazel trees for coppicing in parts of the garden.
Wood is a carbon neutral fuel, but if everyone started heating their uninsulated draughty houses with wood, there would soon be a shortage of trees. Insulating the building as much as possible first ensures that we don’t use more than our fair share of trees.