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Earth pipes in Tropical climate  RSS feed

 
Fred Winsol
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Location: Sierras
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Does anyone have an experience/expertise with putting in earth pipes (2-6" dia) to provide cooling for a 'root cellar' type room? ... in an equatorial/tropical climate? 

Any advice on length, type of piping material, precautions, lessons learned would be greatly appreciated.
 
                        
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I have no first hand experience but have been looking into information about them fairly extensively and what I have read suggests not to use them in warm and humid climates. They have major concerns about condensation and humidity in the pipes hosting colonies of molds and mildews which will then be circulating in your air. This is even with weep holes and good slopes and so forth. Warm dry climate seems where they are best used. Just what I've read.
 
Saybian Morgan
gardener
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Location: Lower Mainland British Columbia Canada Zone 8a/ Manchester Jamaica
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winsol I'll go through my pdc video's theres a section specifically addressing the theory behind what your looking to do.
But there's one assumption I made about your post that after re-reading it I realized was stated. I had assumed you were talking about ventilative cooling for your celar room via the solar chimney design. Along those lines all issues of condensation and the dehumidification of incoming air is addressed, it even includes plant suggestions for the plants to put at the end of the pipe where excess moisture collects.
It's also probably why you havn't found much information on the subject.

To save you some time here's a link to the wikipedia on the subject
http://en.wikipedia.org/wiki/Solar_chimney

Essentially one of the key element's i can convey from memory from the pdc lecture's is the minimum length of the pipe needs to be 20m in order for the heat exchange to work and efficiency plateux's at 60m in pipe. It won't create the vacuum that draws the cold moist air up and through the pipes, through the room and out the structure without the black pipe that heat's up during sun exposure. Oh another critical, if the pipe extends out the building as a chimney , it should be no more than 2 meter's in length of the vacuum will become to great and it will start to rumble.

I can expand if this solution resolves your project apprehensions and the wikipedia leaves you devoid of permacultures perspective on the subject.
 
Dave Bennett
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Lots of good "stuff" about using the earth as a heat sink for a mostly passive system.
http://www.sunnyjohn.com/indexpages/shcs.htm
 
Fred Winsol
Posts: 155
Location: Sierras
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These are great replies and ideas, thanks! One thing I also learned was to put in some sort of 'air densifier' to let the condensation from inside the pipe drip into some sort of gravity trap at the lower end of the pipe. I think earth pipes are very effective in relatively dry soil areas, but in perpetually wet/moist warm soil, it's a whole other ballgame.

thanks!
 
Fred Morgan
steward
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Location: Northern Zone, Costa Rica - 200 to 300 meters Tropical Humid Rainforest
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If you can situate your house correctly, you can take advantage of breezes, but also, if you have some large springs, you might be able to make use of this temperature differential. Since a tropical climate that isn't dry usually have lots of rain, you might be able to tap into a spring. I have a design in mind for a new home which will be cooled using spring water (we have a spring above this area which is a 4 inch "ojo de agua", or 4 inch spring that comes straight out of the ground, forming what looks like an eye. Spring water tends to be colder than the surrounding air, even in the tropics. I am thinking of perhaps running it though a serious of radiators, which will create condensation and cooling, resulting in cooler, drier, air.

But then again, we don't need much, since the temperature here is pretty comfortable for us, around 80.
 
                        
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a site which gives some data on earth tubes ( they don't like them for humid climates, but they don't say "never do it!!")
http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12460

OTOH This link is to a study done in India so perhaps could be of interest. They didn't extend the study for very long, it seems, but had positive results. You could look up the weather data for the area and see if it corresponds with your own.
http://www.builditsolar.com/Projects/Cooling/Earth%20Tubes2003-01-07GirjaSharan.pdf

This may be a silly question, but do zair pots work only in dry climates or would they work in humid climates too? Could you do some sort of big brick version of a zair pot? Evaporative cooling certainly works spectacularly well in dry weather, maybe not in humid climates. If you generally run around 90 or 100 % humidity then possibly not, unless you also had wind. I have no idea what the "tipping point" might be without wind.
 
Dave Bennett
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Pam Hatfield wrote:a site which gives some data on earth tubes ( they don't like them for humid climates, but they don't say "never do it!!")
http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12460

OTOH This link is to a study done in India so perhaps could be of interest. They didn't extend the study for very long, it seems, but had positive results. You could look up the weather data for the area and see if it corresponds with your own.
http://www.builditsolar.com/Projects/Cooling/Earth%20Tubes2003-01-07GirjaSharan.pdf

This may be a silly question, but do zair pots work only in dry climates or would they work in humid climates too? Could you do some sort of big brick version of a zair pot? Evaporative cooling certainly works spectacularly well in dry weather, maybe not in humid climates. If you generally run around 90 or 100 % humidity then possibly not, unless you also had wind. I have no idea what the "tipping point" might be without wind.


Evaporative cooling is ineffective in areas of high humidity.
 
                        
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ok thanks Dave. I thought probably not, but wasn't sure. We'd used something similar in Mexico with success but the humidity wasn't that high where we were so thought I'd ask just in case someone knew, and you did.
 
Dave Bennett
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Pam Hatfield wrote:ok thanks Dave. I thought probably not, but wasn't sure. We'd used something similar in Mexico with success but the humidity wasn't that high where we were so thought I'd ask just in case someone knew, and you did.

Yeah there are "swamp coolers" all over the southwest and as an air cooling device they work quite well. When I was living in California I would turn mine on in March or so and leave it running until the cool weather arrived in the very late Fall.
 
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