Hi,

I have a small question regarding the thermal mass ratio to solar glazing in a passive solar house.

My house will be built on a stemwall foundation with a concrete floor slab in québec. My choice would be for the whole floor to be ceramic tiles over the concrete wich will be insulated under and that would be awesome thermal mass.

My wife don't want ceramic in most of the house and we settled for ceramic in the great room ( south exposure). The rest of the house will have 2x4 sleeper on the slab and wide plank pine flooring on top.

so my question: since the concrete slab in the whole house is in direct contact with the concrete slab heated by the sun on the south side. Can it count like mass not in direct contact with sunlight ( 40 to 1 sqft ratio). I also though about putting sand between the sleepers, that would at least eliminate the air gap...

So basically, how do i calculate the mass that is a continuous slab but will have wood flooring on top?

thanks a lot, hope you understand it, english is not my main language.

Alexis

Are you going to blow air under the floor so that the air can exchange heat with the concrete?

no it will be only passive. My tought is that since there is a direct contact between the exposed concrete and the non exposed concrete, there will be heat transfer between the two. So the exposed concrete would heat because of the sun, transfer the heat to the rest of the concrete that isn't exposed ( basically acting like a big heat sink). Then when there is no sun, it will go the other way.... just not sure how to calculate that exactly...

There will be some, but mostly at the edges. It's hard to get a significant amount of heat to travel very far laterally through a concrete slab. Figure about R1 per foot. The pine flooring will make the concrete under it less effective than exposed concrete.

Any reason why you wouldn't just leave the slab exposed?

yes, my wife :-)

yes, my wife :-)

My suggestion would be to include some pex tubing loops in the floor and attach them to a solar powered circulating pump...not quite a passive system but it operates for free.

you mean having pex tubing and a storage tank as a mean to add thermal mass?

 

Alexis

No. Only to distribute the heat from the exposed slab to the rest of the slab.