Hi Neal,
Depending on the composition of the soil and the difference in temperature, the ground will absorb heat from the warm air passing through the tubes at different rates. If the ground is insulated above, as in PAHS, the ground will hold this accumulated heat and store it so that cold air passing through the tubes in winter will be warmed. This is great because it preheats fresh air in winter and reduces or eliminates the need for heating in winter, but if it warms too quickly in summer it ceases to cool the hot air.
Janosh
From:
Sent: Sunday, March 01, 2009 1:00 AM
To:
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.
To:
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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