You need to understand/calculate your target heat demand as a first step so that you know what you need to provide - then decide on the fuel type and the method of distributing the heat.

It could be anything from an electric towel rail in the bathroom with a fan heater for the occasional boost at the highest level of insulation to underfloor heating or radiators fired by a combi boiler at the other end of the scale.

I would assume that it would be closer to the first option above - but how close? I would steer clear of a wood stove because the heat is too local and the room containing the stove will over heat.

Tony of this parish has a highly insulated house with UFH which he doesn't use because it is not needed! AFAIK

Posted By: NedingtonMy partner and I are planning to build a 2/3 bedroom straw bale house. 1 of the challenges is trying to figure out the right heating systems. We have been told by straw bale experts that underfloor heating and/or a wood burning stove would make the house too hot. We plan to have quite a few windows south facing, but as this is the UK, we find it hard to believe no heating is needed. thoughts?

Hello Kathryn and welcome. Congratulations on your goal. I live in a straw bale house that we built and like the environment it provides. I recommend that you think about exactly what you want to achieve, because there are a range of possibilities. In our case, I started with the objective 'I want to build a passivhaus, from straw if that is possible'. I also decided that I wanted loadbearing straw since that somehow feels more genuine to me than other approaches. It does mean that we compromised on the 'natural' and 'organic' goals that are sometimes desired by straw bale builders. So we have 400 mm of EPS under a concrete slab under our feet, and 450 mm of warmcel in our roof. Your priorities may differ and result in different decisions, so it's important for you to understand what they are.

As Peter and Tony have said, one of the first things to do is establish a goal for your heat demand and then model a design and modify it until it meets all your criteria. In my case that was fairly straightforward since passivhaus (PH) rules limit the demand to 15 kWh/m²/year. My house is 140 m² or so, so I know its heat demand is less than 2100 kWh/year. PH also limits maximum heating power to 10 W/m², so I know the heating load is less than 1.4 kW (actually the two limits are alternatives, but my house meets both). That will keep my house at 20°C inside when its -10°C outside.

I didn't know how best to heat the house. I considered gas, but decided I didn't want the complication of an extra utility service and the plumbing that would be involved. So we're all electric. I thought about heat pumps and underfloor heating but decided against the complication and expense. So the first winter we just used a whole load of plug-in electric bar heaters until I fitted a 1.8 kW post heater in the ventilation system. I also wired the wet rooms, the downstairs hall and the living room with radial power circuits, in case I needed heating there. Last year I fitted a 1.8 kW radiant heater in the hall, and a 1.2 kW unit in our ensuite. We have an E7 tariff, so when it's cold I run the post-heater overnight and when it's very cold I put the hall heater on overnight as well, typically at 600 W or 1200 W. So far that has been enough to keep us warm. This year I stopped using the heating in early February, last year it was late March. I generally turn the duct heater on at the start of November. The house usually warms up during the day from sunlight.

After April it gets warm in the house but my wife and I like that. There's supposed to be a brise soleil along the south wall, but that's morphed into a pergola and I still haven't built it. But that will shade the house in summer once I install it. The upstairs is shaded by the roof overhang.

Underfloor heating is a possibility, providing it is controlled properly. You need to run it quite cool, only a degree or two warmer than the house. I believe it can also be useful in summer to distribute heat from the sun from south-facing rooms to north-facing ones. Our north-facing rooms are a degree or two cooler than our south-facing ones.

I too would avoid a wood-burning stove for various reasons, although I know some people are devoted to them.

In my experience an architect who understood how to run PHPP (the PH Planning Package energy modelling tool) and how to design PH was very worthwhile. Again, I know other people have different opinions.