Earth Cooling Tubes in a Tiny House

Hello all, I am 21 years old and am in the process of building my own home on my parents property. The tiny house will be 20’ x 20’ with a loft and a slanted roof. I have been long interested in the idea of cooling tubes and was wanting to incorporate them into my build. I live in Central California just below Yosemite National Park, in the county of Mariposa. Year is mostly dry besides a few months in the winter, but every year it seems to be getting dryer. I was thinking of two cooling tubes around 10” and 6 feet below ground level for around 60’. As far as the plans, I plan to have them below my planned house coming into the floor as I am on a hill. I plan on laying a concrete slab and having them come up into the house on the opposite end of the high part of the loft with windows at the top to help with the air circulation. I would love to have any and all opinions as I am new and this is just me brainstorming with a small amount of prior knowledge.

1. Would these plans work? Please let me know if I overlooked anything.

2. Does anyone have any experience with cooling tubes? The house is only going to be 400 sqr feet with a loft.

3. The house is going to be Off grid with solar and I would love any other energy efficient house cooling and heating options, but mainly cooling.

I have a degree in Biotecture from Earthship Biotecture and have built a similar small structure as you describe. You can see it here: http://www.dragonflyprairie.com/greenhouse/

Your plan sounds solid with the cooling tubes... However, I am not sure you need 2 tubes 60' long. I would think one 10" tube 60' long would be more than plenty.  60' is long especially if the outside air is dry and not too awfully hot to begin with.

Just make sure the cooling tube is sloped down away from the building to avoid condensation or exterior water from flowing back into the building.

The easiest addition to help cooling is a ceiling fan or a fan on the cooling tube or pointing out a window  to help pull more cool air in.

Just my thoughts.

Bill

Yeah 1 culvert could be plenty, and if you can be sure it slopes down and out then that would help with any condensation. If you install a vent near a high point that can be painted black and capped against rain but can be opened for air flow, then the sun can heat it up and used to generate a draw through the air tube without a fan. Not sure how much air flow you'd need to balance with heat gain, as that depends on a lot of variables.

IN the Middle East Air towers are used to pull air through the buildings.
I built one to experiment, it extends about 10 feet above my roof, facing the equivalent of South for you and has louvres to control airflow.
I made a few until it worked.
The area of the opening is about 4% of the floor space.
Since its working I have not altered it again.

Recently I read a paper that suggested a 10% vent size to floor area is used traditionally.

Maybe the different weather conditions effect the dimensions.

I also add to the completed weatherproof building a Dalrac Safari Roof or wall, something I developed.
Its an extra corrugated roof fitted over the existing roof with steel battens and a reflective layer of insulating wrap.
A row of battens run up the roof, spaced 6ft apart.
The good quality insulating wrap is rolled across them,
Another row of battens are laid across the wrap, holding it in place, the full width of the roof or wall, spaced at 4 foot intervals.
The new roof or wall sheets are attached to the horizontal battens.
in full sun, top roof temperature was 76 Celsius, the under roof [ original] was 38 Celsius.

Thats a huge heat load removed from the building.

Russell,
That extra 60' of pipe doesn't cost much, especially not now during the construction stage.  If it were my building I'd go for it.  I don't think you'll ever regret the extra length of tube, but you might regret  cutting corners later.

Thank you for the knowledge Bill! Would 1 Tube really be enough?

Thank you for the input Mark, I have already planned to have the cooling tubes going straight down under the concrete slab.

The pad itself is located on a hill and is cut into the hill somewhat. Right now I am finishing up the retaining walls (Gabion fence rock walls). We have a pad of roughly 40’ x 40’ so with the 20’ x 20’ house I am planning on building I have a little wiggle room. I was planning to have the cooling tube enter the house on the East side (the side closest to the dug into the hill side), coming straight up into the concrete slab. I was thinking of having the cooling tube run ~ 4 feet under the concrete slab then down the hill (West).

Here is another question for anyone who wants to answer.

Once the tube goes under the concrete slab should it move horizontally to around the end of the dirt pad then straight down again to 6 feet below the ground floor? Or should the cooling tube come down from the concrete slab then directly slanted so it hits that 6 foot under the ground floor? The second option would definitely involve more digging but the best option for airflow is just the best option and frankly I don’t know too much about this.

A drawing would help.
BUT, it needs to have a continual slope to ensure water drains out if it appears.
If its close to the surface the cooling effect will not be as good.
If its very steep it may not be efficient because the air speed will rise.

Aussie earth tubes
other earth tubes