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@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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