Mike Oehler’s pit greenhouse design
I see at least two main approaches to building a pit house with earthbags:
1. Mimic Mike Oehler’s greenhouse design using earthbags instead of poles and shoring.
2. Mimic conventional walipini pit greenhouses. That’s what I’ve chosen to do in the following drawing. It’s very similar to typical walipini’s, so follow the directions in the link. Which one is best? It would be good to build both designs and measure their performance to see how they compare.
Earthbag pit greenhouse insulated with scoria or pumice (click to enlarge)
Related:
Earthbag Pit Greenhouses
Note: high quality greenhouse plastic film is recommended, not ordinary plastic sheeting.
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I wrote a review of Mike Oehler’s book that you can read at http://greenhomebuilding.com/articles/earth-shelteredgreenhouse.htm
I think that it is an excellent concept, especially for cold northern climates; in fact I plan to make one for my little homestead, using earthbags. According to Mike having the cold sink is critical to the success of the plan.
With the walipini plan that Owen shows, without substantially raised beds, much of the floor area would not receive enough sun in mid winter where I live.
Follow the guidelines in the Benson Institute PDF. The design I’m showing mimics the one in Bolivia. They explain how to adjust it for various regions.
We are looking at using earthship design for our greenhouse project. Using old earth packed tires rather then earthbags would have more thermal mass storage. It will also have a cistern in the back berm for water catchment so the greenhouse will be self sufficient water wise, or as much as possible. We’re putting our plans together for the project next summer. In our winters, East Coast Canada, we need to put a thermal wrap behind our thermal mass wall and floor to help keep in the heat. Should be a fun project… Google earthship to check out these spectacular self sustaining homes.
I like the idea of adding a cistern next to the greenhouse. Have you heard of earthbag earthships? People recognize the excellent design of earthships, but now they’re starting to build them out of earthbags because they’re faster and easier to build. Use 24″ wide bags and you’ll have almost exactly the same thermal mass.
http://earthbagbuilding.wordpress.com/2010/11/06/half-moon-earthbag-earthship/
http://earthbagbuilding.wordpress.com/2011/08/08/3342/
I remember something written about that cold channel. While I’m not entirely sure the science of it is as simple as he makes it out to be (cold air sinks, therefor we will have a pit for the cold air), having the raised beds does make a lot of sense for ease of access.
Your design looks much larger, though, so raised beds would be harder to implement without a bit of dead space.
Raised beds are a good idea, although they’re not shown. I am showing walkways between raised beds. The size is fairly common for walipini. In fact, I used the walipini drawing in the Benson Institute PDF as a guide.
This is a fascinating project. You could grow all your food in a cold climate. I hope some people build these and report their results.
More useful tips here:
http://www.homesteadingtoday.com/showthread.php?t=361816
http://peswiki.com/index.php/Directory:Walipini_Underground_Greenhouses
The walls of traditional walipini pit greenhouses are exposed soil. That may work in some areas, but it doesn’t seem very stable to me.
Also note how soil excavated from the pit greenhouse could be used to build an earthbag house.
I wonder if it would be better to only insulate the top 50cm below grade with scoria, since we are trying to use the earth to moderate the temperature. If we insulate it, we are taking away the thermal battery effect of the surrounding earth.
I believe it’s better to store heat in the earthbags rather than trying to heat all the surrounding soil, especially in cold climates, which is where pit houses are built.
Think of it like this: the cold/frozen earth would continuously suck heat away from the greenhouse. But with this design, you’re only heating the earthbags and the topsoil in the bottom.
This is an awesome idea! I never thought about the $$ benifits of building an earth bag greenhouse. I was looking into transport containers. (The Big ones) My thought was that if I buried it then I could use it as a tornado shelter as well. (here in Texas)
Burying containers is not safe without extensive use of reinforced concrete or other type of support. They’re designed to support primarily vertical loads. The horizontal thrust of subsoil would crush the sides of the container. Read the Renaissance Ronin blog. http://renaissanceronin.wordpress.com/
Make your tornado shelter out of earthbags. An earthbag dome would be perfect. It could be buried or partially buried.
http://www.instructables.com/id/How-to-Build-an-Earthbag-Dome/