Lesson: new houses are not like old houses

One thing that becomes clear from any research at all is that houses being built now don't work like any house that we've lived in before. Just to meet basic building regs these days requires really high levels of insulation, and if you exceed those and head towards the so-called Passivhaus standard then you don't really need to heat the house much at all. In fact you have to limit the amount of south-facing window, or at least have overhanging eaves to shade the glass, otherwise the place will fry in sunny weather - technically known as limiting solar gain. New houses also need to be very much more airtight than they used to be, which further limits heat loss - but also means that you need to think about ventilation. The obvious answer is to have managed ventilation where you deliberately trickle fresh air around the house, and these systems have a heat exchanger on them so that the warm outgoing air preheats the cold incoming air. Simple, eh? Initially we thought we'd go for a ground-source heat pump and underfloor heating, as that seems to be the greenest way to heat a house, but Alan's been doing the sums and reckons that we will need around 3kw to heat the whole house - one plug-in electric fire would provide that. So there doesn't seem to be any reason to do something as complicated as a heat pump and a heating system. There are various options instead - you can do it with electric heaters, a small boiler, a log-burner, or a top-up heater on the ventilation system which will add a bit more heat to the incoming air when needed. All have different capital and running costs so there's a cost analysis to be done there... I bet you can't wait to see the results published!?!