[Strawbale] Sub Floor Radiant Heating

[Speireag Alden]

On 2007, Nov 27, at 03:04, Ilan Ungar wrote:

> I have been receiving the straw bale discussions for years now  
> since I am
> very interested in the issue. My wife wont let me build our house  
> out of
> straw but I am contemplating having the second floor made from SB
> construction, this floor will serve me for a studio etc.

     Interesting.  One thing to check is whether the existing walls  
will take the load.  Straw bale walls are heavy.

> Recently, I have heard that sub floor radiant heating poses a  
> problem since
> it lifts the dust and raises it off the floor. Is this true?

     No.  I have a radiant floor, with PEX pipes which circulate hot  
water.  I'm in the middle of putting an addition on, and there's  
plenty of dust tracked in.  I'm looking at a very dusty floor as I  
type this, and the heat has been running for awhile, and none of the  
dust is rising up off the floor.  (And it never has, under similar  
circumstances.)

> Is it serious
> enough a problem to force re-consideration of the sub floor heating
> solution? are there any other serious considerations with the sub  
> floor
> radiant heating system?
>
> On the same issue, how do I determine the slab thickness (I assume  
> this is a
> function of the amount of sun I receive during the heating season)  
> and, how
> feasible is it to have the compacted soil, under the slab, function  
> as part
> of the heat sink (with insulation around the perimeter of the slab)

     This is where you run into problems.  If all of your heating  
energy is from a completely renewable and non-polluting resource,  
then it's probably okay to combine radiant heat with an earth-coupled  
floor.  However, in an earth-coupled floor, you lose a lot of heat to  
the earth.  If you're burning wood or fossil fuels or grid  
electricity to heat that floor, you're wasting a lot of fuel.  You  
don't get all that heat back out of the earth.

     So, I recommend that you either insulate under the slab, or use  
some other heating method.

-Speireag.