Good points Greg,
I Imagine the ground temperature might be a Good place to start calculations to determine how fast heat will be transferred. If you bury a pipe of a given diameter and length at a given depth and direct outside air through it at a given pressure or CFM you can take temperature samples on incoming and outgoing air. I imagine the difference will decrease over time as the soil is warmed. Temperature samples at different distances from the tube may indicate the minimum distances between tubes necessary to avoid saturation.
Janosh
From:
Sent: Tuesday, March 03, 2009 6:59 AM
To:
Subject: Re: [papercreters] Earth tubes
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@comcast.
To:
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
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 wouldn’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
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