Papercreters: [papercreters] Re: Earth tubes

Tuesday, March 3, 2009

[papercreters] Re: Earth tubes

--- In papercreters@yahoogroups.com, Greg House <ghunicycle@...>
wrote:
>
Years ago THE MOTHER EARTH NEWS had an article about a house in the
Nevada desert. He had 4 inch tubes to each room, with fans at the
input. His were 4 ft deep and 100 ft. in length, and he used a sort
of cupbola (is that how it's spelled?) to draw air up from the house
which set up a cooling action. He stated that somebody told him the
tubes only had to be 60 feet long because that was the saturation
length. Seems like the depth should have been 6 ft. because the Earth
is supposedly 58 degrees constantly at that depth, but I could be
wrong on that. The guy said he never had to use the fans in the two
years he'd been lving there. Has somebody else brought this up, I
haven't been following this closely. If so, excuse me.

If you are running hot outside air through the earth tube, through
cooler ground, the heat will be transferred to the ground. At some
point, the heat transfer will saturate the ground surrounding the
tube and you will not get any more cool air through it. The amount of
heat required to do this will depend on the size of the tube, it's
length, the amount of heat transfer to the earth, the amount of heat
the earth can absorb and dissipate, the ambient air temperature
that's running through the tube, and the starting temperature of the
ground around the tubes. It would be nice to know these things so you
could determine sizing of the tubes, otherwise it's just a big guess.
>
> Greg
>
>
>
>
> ________________________________
> From: Neal Chabot <sire@...>
> To: papercreters@yahoogroups.com
> Sent: Sunday, March 1, 2009 3:59:35 AM
> Subject: Re: [papercreters] Earth tubes
>
>
> I don't understand what is meant by "ground heat saturation" when
it is cooling that is being discussed. Of course hot ground will
not provide cooling, but do you plan on heating the ground? At a
certain depth the ground has a relatively constant temperature.
Naturally as the temperature rises and it gets hot outside, at a
certain point the heat is greater than the coolling that the ground
can provide through basement walls. That is why if there is sole
reliance on earth tubes there has to be some calculations of heat
transfer and an understanding of limitations. .
>
> Neal
>
> ----- Original Message -----
> From: "Greg House" <ghunicycle@yahoo. com>
> To: papercreters@ yahoogroups. com
> Sent: Saturday, February 28, 2009 7:40:43 AM GMT -07:00 U.S.
Mountain Time (Arizona)
> Subject: Re: [papercreters] Earth tubes
>
> Janosh wrote:
>
> >The fact that condensation may take place
> >in earth tubes could be a major reason of concern because mold
will probably
> >begin growing in these tubes and become airborne. I wouldnâ€™t
want to be
> >breathing it
>
> Everything I've read about them says that it's important to provide
drainage in the tubes and to regularly clean them out. A swab can be
run through them with a string which should eliminate any mold
accumulation.
>
> My concern is about ground heat saturation. If the ground is heated
around the tube, you won't be able to get any cooling effect by
passing air thorough it. I'd like to understand at what point that
happens.
>
> I do know that in early spring around here (Kansas) you can use a
fan to bring cool air up from your basement and it'll cool your house
(provided you have something to control the humidity), but when it
warms up sufficiently outside, there isn't enough surface area in the
basement walls to overcome the amount of heat that gets transferred
and the cooling stops.
>
> Greg
>