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

[David Anderson]

http://www.greenershelter.org

This link may work better if you are having trouble with the one below.

David Anderson 


On Friday, February 06, 2009, at 12:17PM, "catrambull" <catrambull at fastmail.fm> wrote:
>Hi, I am pretty new to all of this, but am always very interested in these
>discussions and read my coblist emails avidly. Re; thermal mass, insulation
>and flooring, I have come across a very interesting alternative building
>technique called "annualized geo solar" that stores passive solar heat gain
>in the earth under the house during the summer (which cools the the house)
>and heats the house during the winter. The system seems easy to do, great
>for northern climates and may be good for your situation. Here is the link:
>http://www.greenershelter.org.  I would love to hear anyones feedback on
>applying this system for cob buildings in northern climates. Thanks! Sean
>
>On Thu, Feb 5, 2009 at 4:30 PM, Shody Ryon <qi4u at yahoo.com> wrote:
>
>>
>>
>>
>> --- 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
>> > Date: Thursday, February 5, 2009, 1:57 PM
>> > I hear you on the 'more insulation would be more
>> > efficient', unless by
>> > insulating my floor away from my stem wall I'm cutting
>> > down on my total
>> > thermal mass I'll be heating up, thereby not storing as
>> > much when I'm
>> > putting heat in, thus losing more quickly when I'm not.
>>
>> When I think of more insulation, I am thinking of including thermal mass. I
>> think the best design of thermal mass is to have a lot, or even most of it,
>> in it's own insulation envelope separate from the living space insulation
>> envelope.
>> In a mild climate, this is less important and you mind as well use the
>> thermal storage of the cob to it's advantage; insulate exterior to it and
>> any and all other structures at the perimeter and create an insulation
>> envelope, not just at the walls and roof, but under the floor, as you have
>> indicated.
>> the straw under the floor has been debated on some other lists recently.
>> There are some that think it is a bad idea to have straw below grade in a
>> manor that allow it to get wet. This may seem obvious or easy to deal with
>> but apparently it is difficult to do this well; in a way that preserves
>> straw long term. Some insist that every time it has been documented it has
>> failed, as I understood it. I did not really follow along with the posts
>> that closely, but that is what I think some prolific posters were saying. So
>> I think it is would be good to make sure, one way or the other.
>>
>>
>> > I know I'm not going to put store-bought insulation
>> > under the entire floor;
>> > I will put a lot of straw in my sub-floor though. The only
>> > question is
>> > whether to put store-bought stuff maybe a foot in
>> > (horizontally) from the
>> > wall and whether to put some vertical or not.
>>
>> I assume mixing the straw with the mud is a good strategy, especially
>> obviously if it is a known subfloor technique.
>>
>> > Being the cheap, all-natural-wannabe that I am, I'd
>> > like to skip this step,
>> > but my wife is thinking differently.
>>
>> So there is a trade off, burning gas is not all that "natural" so you will
>> apparently be using one or the other, one once and the other every time it
>> gets cold, depending on the efficiency of the solar heating system/thermal
>> storage.
>>
>> > Our roof will be pretty strong: minimum R value for our
>> > area is 19, we'll
>> > have R28 insulation under a steel roof and a 2 inch air
>> > gap.  It'll be
>> > better insulation than our cob walls.
>> > Tys
>> code minimums are minimums based on not much. code minimums used to not
>> address insulation at all. In the future they will be higher than they are
>> now.
>> I wonder if are you ok being very hot? I think it gets very hot in some
>> areas of northern california, if you are in a hot area R 28 seems like it
>> might be low. Are you going to run an AC system? If so, you might use a heat
>> pump for most of the heating. What if you could have insulation at a rate
>> that eliminate the need for heating or cooling? Accept for the solar system
>> for heating? I am not sure this is practical for a cob project.
>> If you wanted to have additional thermal storage for heating and cooling
>> air in your house you might consider
>> http://thermalattic.com/
>> It doesn't show it yet but can be used to cool in hot weather.
>> Shody
>>
>>
>>
>>
>>
>>
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