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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