NOBS
New Member
Posts:1
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| 11 May 2009 03:51 PM |
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Hey guys I'm new to the forums, Can anyone give me some information on earth tubes? Thanks
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| National Owner Builder Services:<br><br>951-304-7777 |
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Polycore
New Member
Posts:79
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| 12 May 2009 02:59 PM |
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"Earth cooling tubes present an alternative for controlling temperature
within residential and office buildings as well as greenhouses and
other structures requiring temperature regulation. These tubes run
underground and alter air's cooling or heating temperature before it is
allowed into a home or office. En route, the air releases its heat to
the surrounding soil so it becomes cool air when it reaches its target
structure. If the soil surrounding the tubes is warmer than the air
within, the air acquires heat so it becomes warm air when it reaches
its target."
source = http://www.tech-faq.com/earth-cooling-tubes.shtml
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| Polycore Canada Inc.<br>www.polycorecanada.com<br>1-877-765-9267 |
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Alton
Veteran Member
Posts:2164
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| 12 May 2009 04:39 PM |
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I have used earth tubes and I think it is critical that the tubes be sloped for drainage. Also be sure to protect the ends at grade with mesh to keep critters away. In some applications without grade being available I have seen the tubes protrude above the earth and then turn 90° so rain will not enter. My only concern for this type is that of moisture building up in the tubes. I have seen one building that had water in the ductwork that was below grade. Water could facilitate the growth of mold. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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wes
Advanced Member
Posts:810
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| 12 May 2009 04:50 PM |
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Alton,
I have been interested earth tubes for many years, but have never used them. The condensation factor here in the south has always been an issue in my mind, as well. I have always assumed that some type of sloping to daylight, to allow for drainage, would be necessary. Aside from this issue, what are your experiences with earth tubes? How well do they work in our climate?
I have also considered tieing the earth tubes to a box surrounding the outdoor compressor unit of an electric heat pump system, to stablize the temperature of the air used in its heating and cooling cycles. Any thoughts about that hairbrained idea? |
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| Wes Shelby<br>Design Systems Group<br>Murray KY<br>[email protected] |
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Alton
Veteran Member
Posts:2164
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| 12 May 2009 07:04 PM |
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Wes,
I just sent you an e-mail because I could not get this system to accept any of my text I wrote with WordPerfect. It used to work. Feel free to copy it to this forum if you think it would be helpful to anyone. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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jonathanlandrum
New Member
Posts:3
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| 18 May 2009 08:53 PM |
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New guy here and enjoy all the info.
Is this setup different enough from the earth tube to work in a humid environment?
http://mb-soft.com/solar/saving.html
It's basically (if I understand it correctly) a closed system of underground pipes where the air is blown through and cooled off before it returns to the inside of the house.
Jonathan |
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ICFconstruction
Veteran Member
Posts:1324
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| 04 Sep 2010 08:11 AM |
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How well would an earth tube work for a air intake for make-up air or HRV? |
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| Brad Kvanbek - ICFconstruction.net |
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cmkavala
Veteran Member
Posts:4327
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| 04 Sep 2010 10:47 AM |
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Posted By ICFconstruction on 04 Sep 2010 08:11 AM
How well would an earth tube work for a air intake for make-up air or HRV? it would not, the earth tube uses inside air not fresh air |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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wes
Advanced Member
Posts:810
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| 04 Sep 2010 07:02 PM |
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Posted By cmkavala on 04 Sep 2010 10:47 AM
Posted By ICFconstruction on 04 Sep 2010 08:11 AM
How well would an earth tube work for a air intake for make-up air or HRV? it would not, the earth tube uses inside air not fresh air
Chris, I am a little confused by your last comment. The earth tubes I am familiar with always use an outside air supply. Are we thinking about two different things? ICFconstruction, I think the answer to your question is yes, but with cautions. My main concern would be humidity, in my climate. But if that could be controlled, it would certainly moderate the incoming air temps, year round. |
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| Wes Shelby<br>Design Systems Group<br>Murray KY<br>[email protected] |
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cmkavala
Veteran Member
Posts:4327
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| 04 Sep 2010 09:48 PM |
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Wes;
if it was open to the outside, then yes it would bring in fresh air , but it would be unconditioned and would also need a way to filter out pollen, dust , etc. |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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ICFconstruction
Veteran Member
Posts:1324
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| 06 Sep 2010 02:36 PM |
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But before air reaches an HRV it is outside air that is not conditioned or filtered, right? My thought is that by the time the outside air reaches my HRV or continuous fan, the air would be tempered by earths moderate temp. |
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| Brad Kvanbek - ICFconstruction.net |
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Dana1
Senior Member
Posts:6991
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| 06 Sep 2010 03:56 PM |
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Most earth tubes use filtered outdoor air to provide tempered ventilation air, and are suitable for using as the input to an HRV/ERV. If the entry point isn't filtered it'll need much more frequent cleaning, but that's not absolutely critical for the energy-savings to work. It's a standard practice in PassiveHouse designs.
These folks have been at it for awhile:
http://www.thenaturalhome.com/earthtube.htm
As have these (in a bigger more commercial way):
http://export.rehau.com/construction/civil.engineering/ground.heat...geothermal.energy/awadukt.thermo.shtml
There are other schemes out there for using earth tube LOOPS as air-conditioning (both sensible & latent, in some apps) without providing ventilation air, but that's a slightly messier subject:
http://mb-soft.com/solar/saving.html
It takes a lot more tube surface area to do full air-conditioning than it does to simply earth-temper the ventilation air. If the local earth temps are well below the outdoor dew point a reasonable amount of passive dehumidification of the ventilation air stream can be achieved, but in most situations the air flow rate will be such that sensible cooling to about the dew point of the outdoor air would be the best one could expect in summer, even if there was some amount of condensation occurring in the tube. The amount & size of tube you use depends on what your design goals, soil type, and ground temps are. As with anything, there are diminishing returns once you're beyond some size. |
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ICFconstruction
Veteran Member
Posts:1324
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| 06 Sep 2010 08:52 PM |
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I read an article recently in Home Power magazine about a passive solar house that used an 8" earth tube 100', I think to feed the HRV. |
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| Brad Kvanbek - ICFconstruction.net |
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Dana1
Senior Member
Posts:6991
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| 07 Sep 2010 04:47 PM |
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Posted By ICFconstruction on 06 Sep 2010 08:52 PM
I read an article recently in Home Power magazine about a passive solar house that used an 8" earth tube 100', I think to feed the HRV.
That would probably be a PassiveHouse design, like the Urbana house:
http://www.naima.org/pages/reso.../RP064.PDFhttp://www.greenbuildingadvisor.com...affordableI'm not sure how much analysis they did on the design beyond guaranteeing a diameter big enough to keep the duct loading reasonable for the length. Performance will vary considerably by soil type & temp, but good-enough is, well good enough, eh? I'm sure an earth tube that size is enough to provide a measurable benefit to homes with more conventional levels of insulation, but the money might still be better spent on lowering the U-value of the structure. (Hard to say without doing the math.) It's probably not big enough to be the primary air-conditioner for most homes, but it's definitely not nuthin'. |
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ICFconstruction
Veteran Member
Posts:1324
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| 09 Sep 2010 07:29 AM |
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I had to buy 240', as I recall it cost about $460 and maybe a couple hours to put it in. For me it will just moderate the temperatures of the fresh air intake, winter or summer. |
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| Brad Kvanbek - ICFconstruction.net |
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cmkavala
Veteran Member
Posts:4327
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| 09 Sep 2010 08:25 AM |
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ERV's and HRV's by design temper the incoming air thru the core, earth tubes are an unnecessary expense |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Dana1
Senior Member
Posts:6991
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| 09 Sep 2010 02:54 PM |
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Yabbut Chris, the earth tube would increase the average efficiency of the HRV/ERV by more than a handful of percent and limits energy used for freeze-protection cycles, in most of the US it would also provide a modest amount of dehumidification, etc.
Whether it's worth the expense for that marginal boost in ventilation efficiency depends on what your goals are, and where you might have otherwise spent the money. A 100' long 8" earth tube isn't hugely expensive, and boosting the thermal efficiency of an already superinsulated house for similar gains would likely cost more. Not cost-effective for many, sure, but whether it's deemed "necessary" depends on other factors than raw NPV. |
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cmkavala
Veteran Member
Posts:4327
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| 09 Sep 2010 05:03 PM |
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Posted By Dana1 on 09 Sep 2010 02:54 PM
Yabbut Chris, the earth tube would increase the average efficiency of the HRV/ERV by more than a handful of percent and limits energy used for freeze-protection cycles, in most of the US it would also provide a modest amount of dehumidification, etc.
Whether it's worth the expense for that marginal boost in ventilation efficiency depends on what your goals are, and where you might have otherwise spent the money. A 100' long 8" earth tube isn't hugely expensive, and boosting the thermal efficiency of an already superinsulated house for similar gains would likely cost more. Not cost-effective for many, sure, but whether it's deemed "necessary" depends on other factors than raw NPV. Dana; I agree that it would be more efficient by cooling/warming the air, but don't beleive it is worth the time or money, it just not the cost of the materials, it is also the cost of the back hoe to trench deep enoughto be effective. |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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ICFconstruction
Veteran Member
Posts:1324
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| 09 Sep 2010 08:16 PM |
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For me, I had no digging, I need to bring fill in on that side of the house. Inside, I just ran it along the frost wall next to the footing. |
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| Brad Kvanbek - ICFconstruction.net |
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cmkavala
Veteran Member
Posts:4327
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| 09 Sep 2010 09:19 PM |
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Brad; what was the diameter and type of pipe used |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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