I've read long and hard on this topic.
Don't kid yourself. NOTHING IS FREE. AGS and PAHS systems have
significant up-front costs, but your point is well taken.
In my opinion, trying to store heat in any uninsulated thermal mass
is a waste of good btus. I hate wasting energy that can easily and
cost effectively be contained by simple insulation.
AGS and PAHS systems can work, but they are going to be tricky to get
sized right. Soil conditions can vary greatly between houses next to
each other, let alone in different regions. An efficient system
needs to be specially designed for each site taking into account the
conditions on that site. Good ones will still at least have EARTHEN
INSULATION surrounding the large heat battery. In a sense you're
just expanding the floor's thermal mass deeper into the ground and
pushing the foundation insulation envelope further out, but a form of
foundation insulation still exists.
Ground water is a nightmare for these systems. If ground water seeps
into any area of your heat battery, it will carry away all your
precious btus as it drains away. Membranes are advocated to avoid
this phenomenon. One membrane leak in a storm and a YEAR'S heating
can disappear in a day. Finding and repairing such a leak would be a
nightmare. I've seen no proposed remedies for temporary elevations
of a water table after a big downpour.
It's a fascinating concept, but one that I feel would be too
difficult for me to implement well without a great deal of expert
assistance. I need to pick my battles and know my limitations.
Others may see it differently. If they're confident they can make it
work, more power to them. I'll enjoy learning from them what works
well and what doesn't work well in a real world application.
Personally, I'd rather build a large insulated cistern and heat that
tank with hydronic solar. That is something I can do all the design
and calculations myself. I can build it myself using many recycled
or inexpensive components. I can also repair it if it breaks down.
The active controls and thermostats will give me greater control.
Just my personal preference.
--- In papercreters@yahoogroups.com, "Nick Boersema" <picknick@...>
wrote:
>
> Slurry even up here in the cold we are getting people advocating
insulating
> the envelope and not the earth for radiant heat floors. I think
John has it
> down. If you look into Annualized Geo Solar I think the potential
to heat
> your home passively for free is very doable.
>
>
>
> Nick
>
>
>
> _____
>
> From: papercreters@yahoogroups.com
[mailto:papercreters@yahoogroups.com] On
> Behalf Of slurryguy
> Sent: Sunday, September 02, 2007 8:20 AM
> To: papercreters@yahoogroups.com
> Subject: [papercreters] Re: Papercrete: insulation & thermal mass
>
>
>
> Excellent post John. Well done.
>
> You mentioned wondering what plant people are on when they insulate
> under a floor. Why, planet Earth, of course!
>
> Your arguments against that insulation are well taken, but there
are
> situations where underfloor insulation is essential.
>
> Radiant Floor Heating.
>
> Modern hydronic radiant floor heating embeds PEX tubing inside slab
> floors. A low temperature boiler heats water to 80-100+ deg and
> pumps it through the tubing. The entire floor is the radiator.
> Moving heated water is drastically more efficent than moving heated
> air. A small pump motor can transport thousands of btus easily.
> Radiant floor is also one of the most pleasant and comfortable
kinds
> of heating one can have. I'm not saying that this type of heat is
> the only way to go, but it certainly has its place. It is extremely
> adaptable to solar. No nasty bulky ducts to worry about getting
> dirty and having molds, fungus, or dust mites.
>
> When your floor is your radiator, you better have underfloor
> insulation or your heat will go into the ground instead of into the
> house.
>
> That said. I agree with pretty much everything else in your post. I
> will add that the attic or roof is the most important place to
> insulate. Typically 2-3 times as much insulation in the attic as is
> in the walls makes sense.
>
> --- In papercreters@ <mailto:papercreters%40yahoogroups.com>
> yahoogroups.com, "John Annesley" <John@> wrote:
> >
> > My fascination with paper adobe / papercrete has always been with
> making a dense mix
> > because insulation is only a part of the equation which leads to
> energy conservation and
> > comfortable living. Slurryguy is quite right in that insulation
> only evens out temperature
> > swings, or perhaps more to the point- a good jacket keeps you
warm
> in winter so long as
> > your body is producing heat. Stop producing heat and gues what,
> pretty soon you get cold
> > even if you have a whole lot of insulation. The idea behind
thermal
> mass is to collect heat
> > or coolness and store it, and having good insulation on the
outside
> of thermal mass
> > insulates that thermal mass. A down jacket is a good example of
an
> insulation barrier on
> > the outside of that which you're trying to keep warm- you. It
> makes basic sense when you
> > apply it to a person. Same thing applies to houses-- put the
> insulation on the outside if
> > you want to insulate the structure from the outside temperatures,
> period. Putting it inside
> > the wall and then having a brick wall outside of that is pitting
> thermal dynamics and the
> > laws of nature against your wallet when it comes time to pay the
> heating and cooling bills.
> >
> > Quick notes about paper adobe when the volume of paper and the
> volume of adobe are
> > roughly equal in the mix: it makes a dense block, has a lot of
> mass and holds nails and
> > screws almost as well as wood but it doesn't burn or smolder.
> Adding lime reduces the
> > possibility of mold growth if the material stays wet somewhere
down
> the line during the
> > life of the structure, and also increases insect resistance.
(Boric
> acid would also help with
> > this.) Then adding an insulating jacket of lightweight papercrete
> or paperadobe would
> > insulate the thermal mass and produce an energy efficient house.
A
> house composed of
> > insulative blocks can only be energy efficient without thermal
mass
> in temperate climates.
> > Remember, adobe homes in the desert are much cooler than wooden
> houses filled with
> > insulation because they have slab or earthen floors tapping the
> heat sink of the earth,
> > which is much cooler than the mid-day air temperature, and the
> dense adobe walls take a
> > long while to conduct the heat energy of the sun toward the
inside
> of the living space, and
> > those same walls are conducting coolness outward, creating a very
> nice temperature in hot
> > climates. Such a structure with an insulating jacket becomes a
> truly efficient house. Even in
> > cold climates, so long as you dig below the frost line, the
> temperature of the dirt or rock is
> > a fairly constant 55 degrees everywhere in the world. Tap into
that
> and build a home with
> > a lot of thermal mass and insulate it on the outside and you've
got
> winter licked. So often I
> > read about folks putting insulation between the floor and the
> ground and I wonder what
> > planet they think they're on, except that sure- going barefoot
> might be more comfortable
> > if you insulate your floor that way, but its going to cost you in
> terms of the viability of your
> > house being able to regulate temperature without smacking your
> pocket book upside your
> > head for the life of the house.
> >
> > I could be wrong, but I'm going to assume that something without
> paper in it would make
> > a better thermal mass building component, because the paper is
> going to act to some
> > degree as an insulator. So maybe dense paperadobe isn't ideal in
> terms of its thermal
> > mass characteristics. I do like the fact that dense paperadobe
> holds nails, screws, etc. and
> > when hit with a sledge hammer only dents isntead of shattering
like
> a brick or concrete
> > block of the same dimensions. As pointed out in other posts, you
> don't have to build your
> > walls out of thermal mass to use thermal mass effectively: you
can
> have barrels of water, a
> > trombe wall, a geothermal exchange heat pump, etc...
> >
> > The thing to remember is that you need insulation on the outside
of
> the house, which is
> > where papercrete shines because that's what papercrete is: a
> building material that's also
> > excellent insulation. You still need thermal mass unless you're
> fine with the traditional
> > wooden-framed house concept of building an insulative box into
> which you pump heat
> > and cooling.
> >
>
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