DIY Earth Tubes?

I'm starting a project that involves digging out a root cellar here:
ecorenovator.org/forum/renovations-new-construction/2278-backyard-earthship-root-cellar-bottle-wall-sunroom-top.html ( sorry this board won't let me post links yet. )

and I had envisioned an "earth tube" system to circulate air to both rooms at least in the summer, preferably all year.

We do have some temperature extremes out here in the desert, so it seems like a no-brainer to try and get some stability from the earth, not to mention passive airflow or even if we have to power and pressurize it, it would be inexpensive.

My questions are:

1. Corrugated pipe is obviously a bad idea, yet all of the contractors are using that stuff and huge rolls of it. This is a small, one room, space that the tubes will underrun. So, can't I just use ABS? It's smooth-er than that corrugated stuff.

2. What size of pipe and how long should it be for a small application like this? Anyone know of an online calculator or something for this?

3. Can anyone please point me in the right direction for finding info on how to build a "drain" for the earth tube project? Contractors seem to talk about a drain like it's something more than a hole in the ground filled with gravel. If not, what exactly is it? If yes, what are the average dimensions of the thing?

Thanks!

To be able to post links or images your post count must be 5 or greater. You currently have 3 posts.

Please remove links from your message, then you will be able to submit your post.

This is a newbie mistake. Take it from a programmer that fixes sites like this for a living. Worried about a little spam and you're upsetting possible good members. Doh.

PM me if you guys would like some pointers on how to make this a better forum. Normally, I wouldn't offer to help for free. But, this is a good cause.

And, one more. Silly, huh?

Finally, my original post, which I had the sense to copy into a text editor since I'm aware how funky this software has been configured.

Here's an idea using 4" PVC or ABS. The air goes in the upper tubes and gets blown out the top, the treated air comes in the lower openings in each room. I think maybe a small fan might be necessary to keep the air moving the right direction, plus maybe I'd need some sort of one way valves at all the openings?

It would be sweet to make it totally passive, but I also don't want mold. Oh yeah, and the snaking tubing would of course be slanted about 2 degrees or a 1/4" per foot towards some kind of drain area. I still need help with that part.

[S-F]

Remember those "Got milk" commercials?

Got Radon?

[strider3700]

is radon a valid concern in NM? I've never heard of anyone even bothering to consider it up here. I got the feeling it's pretty location dependant.

[TimJFowler]

Re: Radon. This is definitely a concern, depending on where in New Mexico you live and your local geology.

From Wikipedia - 'Radon is produced by the radioactive decay of radium-226, which is found in uranium ores; phosphate rock; shales; igneous and metamorphic rocks such as granite, gneiss, and schist; and, to a lesser degree, in common rocks such as limestone.'

If you are building on/in/near any of the above types of rocks, or if you can find old uranium mines on the USGS quad maps of your area (there are some not very far from my house) - I would suggest getting a radon test.

Re: Mold. This should probably be less of a concern unless you live in a river valley or a particularly wet part of New Mexico. Given the usual humidity levels here (single digits right now) mold shouldn't be too big of a problem.

FWIW,
Tim (living in Northern New Mexico)

[TimJFowler]

Originally Posted by DirtFlinger

I'm starting a project that involves digging out a root cellar here:
ecorenovator.org/forum/renovations-new-construction/2278-backyard-earthship-root-cellar-bottle-wall-sunroom-top.html

...

My questions are:

1. Corrugated pipe is obviously a bad idea, yet all of the contractors are using that stuff and huge rolls of it. This is a small, one room, space that the tubes will underrun. So, can't I just use ABS? It's smooth-er than that corrugated stuff.

2. What size of pipe and how long should it be for a small application like this? Anyone know of an online calculator or something for this?

3. Can anyone please point me in the right direction for finding info on how to build a "drain" for the earth tube project? Contractors seem to talk about a drain like it's something more than a hole in the ground filled with gravel. If not, what exactly is it? If yes, what are the average dimensions of the thing?

Thanks!

If you insulate the cellar walls and above grade walls of the structure (or use an self-insulating material) but leave the cellar floor in direct contact with the subsoil - would you even need the earth tube? The temperature of the earth 8 feet below grade should be quite consistent and suitable for a root cellar.

With the rest of the structure well insulated (or with enough thermal mass e.g. adobe, rammed earth, etc.) the structure should be comfortable year-round. Insulate the floor and you can have a cool root cellar and the above ground sun room (with good shading) could be comfortable for people too.

It's worth your time to talk with a local architect/builder, especially someone who has built structures similar to what you are considering. There is a definite learning curve to designing a building with good passive temperature regulation.

FWIW,
Tim

Originally Posted by TimJFowler

If you insulate the cellar walls and above grade walls of the structure (or use an self-insulating material) but leave the cellar floor in direct contact with the subsoil - would you even need the earth tube? The temperature of the earth 8 feet below grade should be quite consistent and suitable for a root cellar.

With the rest of the structure well insulated (or with enough thermal mass e.g. adobe, rammed earth, etc.) the structure should be comfortable year-round. Insulate the floor and you can have a cool root cellar and the above ground sun room (with good shading) could be comfortable for people too.

It's worth your time to talk with a local architect/builder, especially someone who has built structures similar to what you are considering. There is a definite learning curve to designing a building with good passive temperature regulation.

FWIW,
Tim

Thanks Tim, But if I felt like paying some overpriced yahoo I wouldn't be here asking questions. I'm usually handy enough to not need someone to do it for me.

Isn't it crazy that the first thing people try to do is discourage you from doing anything? Radon? Don't you think I would have thought of that before even considering this? Thanks for your concern, but no there's no radon here.

I like the idea of not even needing the earthtubes but that again is just trying to discourage what might be a good idea.

The idea is to have air constantly circulating in both rooms. Earth tubes seem like a great way to do that and possibly even passively, though I might pressurize the tubes slightly to increase airflow, like in the hot summer months, to help cool the sunroom at least, even if the root cellar doesn't need it.

I hope that settles all this discouragement nonsense now and I can start getting some real input.

Thanks again Tim for the thing about the mold. I didn't think it should be a big concern here in the desert either. I wonder if you have any actual experts here yet though? They do seem to live in this general area and Taos.

Although, so far what I can find online is just rich old hippies trying to make more money off all this so I'm not holding my breath.

Yay, I can post pics now. I also got the hidden geometry turned off in sketchup.