[Cob] radiant floor tubes in clay floor: insulation?

[Shody Ryon]

I am not an expert. ten days (nights) at 32 F. I think most people would keep their house about 70 F maybe 2 or 3 months of heating. Perhaps $60 to $250 of gas a month for 2 months?
That sounds reasonable for a minimally insulated cob house.
A earthen floor is somewhat high in thermal mass compared with air, which is what most of us are used to heating with (me to). There will be a lag time to heating the house with the floor, it will take a while to warm up the house from a dead cold. It may take a lot of energy as opposed to just keeping it warm.
If you wanted to be more energy efficient you could use more insulation. The more insulation that you use intelligently would, I assume, result in less heating costs.
It seems to be popular to do perimeter insulation and use the thermal mass of the ground away from the exterior walls as thermal storage, but with my limited knowledge, this seems like wrong thinking, that thermal storage will be under a lot of constant pressure to return to the average annual site temp, which you will be resisting during winter.  
I have a personal aversion to cold floors, even during hot weather, so I am presenting some of this as I would do it for myself.
The majority of people would probably welcome the coolness from the floor.
Insulation in the floor, a floor of thermal mass that is next to the earth that is also high in thermal mass at the average yearly temp of your site, perhaps 55F 60F? The number is not that critical unless you can get numbers for other things, but I would consider insulating all of it to say R 30. I say consider because I am not expert, I just read blogs and lists.

As for hot weather, I assume that would be a concern, I would consider insulating the roof to R 60 also I would insulate the south and west walls. 
I have been looking at this contraption.
http://www.portafoam.com/portafoam.htm

I would also be interested in following along with your decisions 
Thanks
Shody


--- On Thu, 2/5/09, Tys Sniffen <tys at ideamountain.com> wrote:

> From: Tys Sniffen <tys at ideamountain.com>
> Subject: RE: [Cob] radiant floor tubes in clay floor: insulation?
> To: qi4u at yahoo.com, coblist at deatech.com
> Date: Thursday, February 5, 2009, 1:16 AM
> Right. Sorry. This is northern California, freezes for maybe
> 10 days a year
> total. Mostly worried about hot from May to October. 
> 
> I'm just building the roof with a timber frame
> structure, and the stem wall
> is done.  Cob starting is this next summer, so no
> insulation yet. 
> 
> The radiant tubes will probably be a closed system heated
> via solar with a
> propane tankless backup. 
> 
> Tys
> 
> -----Original Message-----
> From: Shody Ryon [mailto:qi4u at yahoo.com] 
> Sent: Wednesday, February 04, 2009 8:29 PM
> To: coblist at deatech.com; Tys Sniffen
> Subject: Re: [Cob] radiant floor tubes in clay floor:
> insulation?
> 
> Hi Tys
> I forget, what climate is this in?
> Is there insulation anywhere in the house? If so how much
> and were?
> What heating system are you using? solar, gas, electric?
> Shody
> 
> 
> --- On Wed, 2/4/09, Tys Sniffen
> <tys at ideamountain.com> wrote:
> 
> > From: Tys Sniffen <tys at ideamountain.com>
> > Subject: [Cob] radiant floor tubes in clay floor:
> insulation?
> > To: coblist at deatech.com
> > Date: Wednesday, February 4, 2009, 10:36 PM
> > Hey folks, 
> > 
> > as I read about radiant floors, in typical houses,
> they put
> > insulation
> > against the inside, and sometimes outside of the house
> > foundation.
> > Sometimes they make an "L" shape with
> insulation
> > under the floor and up the
> > wall a bit.  My north side will be bermed in, and my
> > southern side is of
> > course, my solar gain side.  Does anyone have an
> opinion
> > about whether I
> > should put insulation in between the clay floor, the
> gravel
> > sub-floor, and
> > my concrete and mortared urbanite stem wall?  If you
> think
> > I should do it,
> > how much (how wide?) 
> > 
> >  
> > 
> > Starting to think about the inside,
> > 
> > Tys
> > 
> >  
> > 
> > www.magnumdental.com
> >
> <http://www.magnumdental.com/application.php?id=tm42> 
> > 
> > 
> > Reasonable Dental Insurance for Individuals... Online
> > 
> >  
> > 
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