How about using the thermal mass of the house to stop it cooling down -- if you are "very well insulated" then any heavyweight construction will take a week or two too cool down to uncomfortably cold, and still be warm through the night and into the morning, so long as you are all air sealed.

I'm with Tony re thermal mass but wonder if water in suitable containers isn't a better option than heavy manufactured materials which need to be transported to the site.

Posted By: Nick ParsonsI have been wondering about crushed brick/block/gritsand/lime as a thermal mass internal wall for lightweight bldgs.

Stone/concrete/brick and the like have much less thermal mass per unit volume that you'd think. In fact, on a volume for volume basis, wood is just as good. So if you install nice solid wooden flooring this can have a bigger effect on thermal mass than you might think .... and after carrying 1.5 tonnes of new wooden flooring upstairs, I can attest to the fact that it has lots of real mass, not just thermal.

All that said, if you're airtight and ventilated right, this will have a much bigger impact than anything else. I speak from experience here of having a well insulated airtight wooden frame house that, by the definitions of the thermal mass brigade on this forum is "lightweight" but which is very thermally stable. For example, the temperature changed from low 20s outside to teens and it was a couple of days before the temperature had fallen by 1C inside. Thermal mass is only useful if you have a way of capturing solar gains in it - if you don't then it's not of much use - especially in a Scottish climate in winter when there's precious little solar gain for weeks on end (or is that the summer?!). Thermal mass only works if you have a large diurnal temperature change with insolation being the main driver. If you don't then there's no real benefit assuming you're well insulated and airtight with heat recovery ventilation. And if you don't have these latter two items attended to, you're wasting way more energy than you can store in a pile of old bricks anyway (which isn't very much if you actually calculate it).

Paul in Montreal.

The reason I asked the question is because Rachel mentioned on another thread that her straw bale house got chilly in winter if she didn't have the stove burning in the evening. I didn't think staw bale houses got chilly which is why I am a bit worried.

Our new build will have staw bale walls set in a timber frame with clay plastered walls on the inside and larch cladding on the outside. The floors will be a mix of solid oak and tiles. Is this enough/good thermal mass to retain heat? We will also have heat recovery.

Paul in Montreal - I think the heated bathroom is the way to go, although I was thinking along the lines of a large heated towel rail on a timer rather than a heated floor.

Straw bale tends to be nicely air tight but problems will exist with where they join to fenestration, roof and floors etc.

Posted By: tonyStraw bale tends to be nicely air tight but problems will exist with where they join to fenestration, roof and floors etc.

Why Tony?

Doc - the plan is to have a stone built chimney stack in the wall with a double sided stove, one side facing into the lounge and the other into the hallway. So I would expect this to ratain quite a bit of heat. We also want to use old stone for the porch so I would like to take you up on your offer of the sandstone. What is your email?

Posted By: stephendvThe guess is based on a completely unfounded and unfairly generalised hypothesis that there are 2 types of greens on this forum, the techno-greens and the naturo-greens.

I think we should at least mention a third possibility - appropriate technology. That is, not eliminating technology for the sake of it - being open minded, or including technology for the sake of it.

I suppose I am thinking of an evidence based approach to decide what is a appropriate.

(I am not looking for a fight )

Peter

Ah yes Tony, 'potential' air leakage if not done properly - I agree. You previously said there 'will' be problems with any join, not potentially.

Showering in an air tight house must do wonders for the humidity. I'd be sweaty again buy the time I'm dressed.

Posted By: StuartBThere is no gas supply. What would you use to provide a blast of heat first thing in the morning to make the house a bit more comfortable? My wife won't accept any replies of "put on a woolly jumper"! She will want to dry off after a shower and dress without wrapping a duvet around her at the same time!

I'd go air/air heat pump. Fast response, programmable and very efficient.