In a passive house does a wet room feel cold to touch with your feet. Wondering if i need towel radiators and a bit of heating under the tiles (it will also dry them out faster). Look forward to hearing your experiences?
@neilgswift

Thanks Robin,

So I don't bother with the towel radiator and just go with UFH in bathrooms relying on MVHR to dry towels in winter and summer when hung on a rail? This underfloor heating would then heat the whole house when required.
Sounds like a strategy.

Thanks

I have nearly finished my Passive bungalow and found the MVHR works when you have little heat in many places. If you try running a bathroom very warm it will not distribute around the building via the MVHR unit.

I am experimenting with electric under floor heating in one bathroom with a towel rail. The towel rail has a controllable thermostat head, hopefully getting the best result all the year.

We have come to the conclusion that a comfortable house must have the bits you like and underfloor heating in bathrooms is a must for us. Using electric underfloor mat you have relatively quick response and controllable while you experiment.

Thanks for all your comments.

Posted By: johnureadywill not distribute around the building via the MVHR unit.

isnt the whole point of passive house was to do away with heating for most of the year and the little bit you have gets distributed around the house via MVHR?

Posted By: djhI don't think the UFH in your bathrooms will heat the whole house! Not without making the floor uncomfortably hot, anyway.

Well that's where i need to check my PHPP heat requirement and balance it?

Look forward to comments

Posted By: djh

Posted By: neilgorswiftisnt the whole point of passive house was to do away with heating for most of the year and the little bit you have gets distributed around the house via MVHR?

Yes and no. The ability to heat a Passivhaus via the MVHR depends on the incoming air being heated to 50°C or so. That is, the air needs to be heated by a heater in the ventilation duct, not by redistributing lower temperature heat from other rooms.

50°C is the upper limit to which you can heat the air in the ventilation ducts, above that temperature dust particles will burn and you will get a bad smell in the house.

I had a guy do heat loss calculations for me on all the individual rooms in the house and he calculated that the worst room would need to be supplied with incoming air at 33°C in order to balance heat losses from the room at an ambient temperature of -10°C (pretty much the coldest we experience here).

Bear in mind though that the Swedish building regs (where I am building) call for higher ventilation rates than in Germany so because of the higher airflow it is a little easier for me to add heat in this way (but also I have greater ventilation losses).

In the end though I decided not to go down this route as I have read too many times that people who have heated their houses in this way were unsatisfied with the result.

I installed water borne UFH in the ground floor slab for heating and will also have electric UFH in the two bathrooms for comfort heating for a greater part of the year.

I can't remember the specific reasons but from recollection people were saying that it just isn't a comfortable type of heat. I think there were issues with low humidity tied in with it and in general it is difficult to control such a system.

I had my ventilation layout designed so that it is split into two sections one upstairs and one down so that it would give me greater control, I didn't want the bedrooms too hot, but at the end of the day I just decided that the safer option was to go with UFH downstairs.

Apart from the electric UFH in the bathroom which will only be timed to be on a few hours a day I don't have any heat emitters upstairs. I will suck it and see the first winter and add some electric panel heaters if it proves necessary in any rooms but my feeling is that it won't. We only occasionally heat the bedrooms in the house we currently rent and it is a long way off the insulation levels of the new house.


PHPP has default ventilation rates at the level of the German standards and all assumptions are based on that. I don't have the figures in front of me but I do know that at the German ventilation levels it wouldn't have been possible to heat the house via the ventilation system but when the ventilation rates were increased to the Swedish levels it then became possible to do so.


As part of the planning procedure here we must give the council documentation to show that the ventilation system has been commissioned in accordance with the regs but my feeling is that we will back off the fans to a lower level after we move in.