Cob: RE: Thermal mass and climate

[Patrick Newberry]

Hey Kerry, 
I live in Middle GA, the approach, which is going to be test this summer, 
with my cob house is use of air flow. I have a fan that will pump in air from one side of the house, 
with opening / exit vents on the south side (air comes in from the north side). I won't 
have a full report till july and august dog days arrive, but being in middle GA, there should 
be sufficient heat and humitity to test performance in most regions of the US. 

Pat 

-----Original Message-----
From: Kerry S Tebbetts [mailto:yourelovedbygod at juno.com]
Sent: Sunday, April 22, 2001 4:17 PM
To: coblist at deatech.com
Subject: Cob: Thermal mass and climate


Hi, 

I live in central Arkansas where the Thermal flywheel effect of cob can
produce uncomfortable interior summer temperatures.  I was first drawn to
cob and light straw-clay because they are moisture absorbers as it is
also quite humid here in Arkansas.  I also like the architectural freedom
(within reason) one has when working with cob.  However, as I pointed
out, there's that thermal flywheel effect doing a nasty number on us in
the summer.

So, what's the solution for staying cool in the summer?  Is the answer to
block solar gain by using exterior insulation? (in combination with solar
orientation and proper window/thermal mass ratios, of course)  If I were
to use an insulating material (i.e. light clay-straw or clay-sawdust) to
form the north, east and west walls as well as roof, while using cob for
the floor and south wall, would that solve my summer problem?  Would this
solution to the summer problem hinder the cob's effectiveness during
temperate months?  Would this "solution" help in the winter when the
massive cob walls never have a chance to heat up to the point of
effectively heating the house?  

Here's another solution I've been mulling around.  We all know that water
has a higher thermal mass and has been used to more effectively store
heat for winter heating.  There are different variations of this for
heating (i.e. water wall, solar closet), but has anyone thought of a way
of using it for cooling - even in humid climates where the roof pool and
earth tubes aren't advisable?  Could you not strategically place
containers of water around and/or in your house, allow them to heat up
all day, and them empty them before their thermal load is reached at
which point they'll start to radiate heat in your house?  I don't mean to
manually dump them.  Perhaps they can be all connected with pipes and
flow by gravity into a cistern for later use (i.e. watering plants,
bathing, cleaning, etc) or somehow be cycled back to the solar collectors
once the water has been cooled (or emptied of it's thermal load).  In
essence this would be like the roof pool, only rather than having to wait
around for the water's heat to radiate back into the air (which doesn't
solve my summer problem) you'd dump it immediately carrying away all of
the day's heat.  I don't know if this water would be kept separate from
the wall in plastic or metal containers or if it would be incorporated
into the cob wall.  The thing I don't exactly understand is how
condensation might pose a problem?  If the containers were embedded in
the wall, would condensation occur inside the cob?  How would heat travel
through a "cob water wall"?  Would it travel through the cob and then get
stored in the water moreso than the cob?  Or would it be stored in the
exterior and interior cob moreso than the water?  


Shae