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Zach Weiss
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Posts: 296
Location: Montana
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I recently finished up another Earth Powered Greenhouse; a greenhouse designed to use the resources that are naturally available. I have been developing this design for a couple of years, visiting every greenhouse I heard of to learn from the creator's successes and failures. I've got a ton on my plate right now but I want to get some pictures on Permies for other people to get ideas from; so I apologize if I am slow to respond.



This greenhouse is designed to run a dormancy, as here in Montana we do not get enough minimum daylight hours in the winter to support tropical species. It employs passive heating and cooling, and will be established as an ecosystem with natural pest control and fertility.



The greenhouse does not use any heat or electricity for performance (although there is electricity as it also includes a lap pool). The rainwater collection system is also entirely passive (though we do use electricity at times to decrease time spent watering).



I am happy to report that so far I am very pleased with it's performance. Despite -20f temperatures at the time of this photo, and -30f the night before, the greenhouse remained a toasty 31 degrees without supplemental heat of any kind. The greenhouse was not sealed up until the late fall, and should perform even better with the full thermal buffering of the summer. Once it is full of life the humidity will also help buffer the temperature.



This greenhouse is on the northern edge of a Krater Garden that we created this past summer.

 
William Bronson
Posts: 1413
Location: Cincinnati, Ohio,Price Hill 45205
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forest garden trees urban
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Nice! What did you use for the roof?
 
Jen Shrock
pollinator
Posts: 363
Location: NW Pennsylvania Zone 5B bordering on Zone 6
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Zach,

Thanks so much for sharing. It is always great to see pictures of the various site development projects you are working on. How much, temp wise, does the crater garden raise the temp? Does it have to be a true round/oval crater or could it succeed as a "U" shape with the opening part facing south for maximum heat gain?

What would you suggest for greenhouses in areas that cannot dig down into the earth due to high water tables? (I have a very tiny greenhouse that sits on a single course of railroad ties that are 90% sunk into the earth and I have to wade through water almost to the top of the railroad ties for quite a while in the spring.) Is there a way to achieve this same style of system with passive heating and cooling in an above ground situation (possibly strawbale for insulation)? I am not sure about being able to gain the true benefit of using the earth for heating and cooling with such a high water table, though. I would like to grow my greenhouse to a size that is more climatically stable and that can be used to support tender species many zones warmer than where I am at.

Thanks again for sharing!

Jen
 
Tim Malacarne
Posts: 226
Location: South central Illinois, USA
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My compliments! Looks like first class workmanship! Did you insulate the exterior walls?

We have a fairly crude sort of solar growhole or coldframe, really. Is 8' X 16', you can walk in. I have insulated the beds from the perimeter walls, looks like to good advantage... I plan to add a means of bottom heating over the summer, ought to help the stuff grow.....
 
Zach Weiss
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Posts: 296
Location: Montana
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The roofing is 3.5mm Solexx double walled polyethylene. It has an R-value of 2.1, 77% light transmission, 100% light diffusion, and only costs $1.55 per square foot. It is by far the most cost effective glazing solution that I've come across. It has a 10 year warranty, lasts 10-20 years, is as insulative as triple walled poly-carbonate, yet is only a fraction the price. Furthermore it can be lapped, meaning you don't need to buy H-channel and U-trim (an added expense of poly-carbonate). And it comes as a roll, reducing the cost of shipping and making it easier to handle and store. You have to order it through one of their dealers but it ships quickly and cheaply. I am one of their dealers and am happy to offer a discount for all the Permies out there, just let me know your on Permies at the time of order.

We don't have a data logger in the Krater Garden yet but it will be coming soon (as the construction of the project is now mostly complete). I don't get the impression that during the dead of winter that there is a huge increase in temperature in the Krater. The benefits are more from wind protection and water retention. Similar as in a greenhouse water and wind are the most stressful and damaging factors for plants; when protected from the wind plants can withstand much colder temperatures. During the change of seasons the humidity from the pond and the thermal mass of the Krater provided a significantly warmer and more humid micro-climate. I think this is where the majority of the season extension comes in. Krater Gardens are formed to the natural topography, so they can and should be water shape the landscape presents. It is important to take all of the factors into account in the design (wind protection being a big one) but the more natural shape the better!

The original greenhouse is actually in a location with a very high water table (5' below grade) and it has provided an immense benefit to the greenhouse. The ground water provides a temperature and humidity buffer. If the water table is even higher than this (as it sounds yours might be) then you can take a two pronged approach. First berm the greenhouse above grade as much as possible. If I were in your situation I would put in a pond and use the excavation to create a big berm around the greenhouse. As long as the berm angle is 1:2 or shallower then you should get the same heat benefits. The other thing to do would be to add a french drain (or several) to reduce the tension on the foundation. This would drain the water around the foundation into the pond.

The exterior walls of the greenhouse are all insulated, as is the earthbag foundation. This time the walls are extruded polystyrene insulation with stucco. I've used dense pack cellulose (recycled paper insulation) with stucco in the past with good results. I used the polystyrene insulation this time because a friend had salvaged it, so it was re-used and cheaper. The stucco provides an additional thermal mass.

I really love the idea of a "solar growhole" simple earth powered greenhouse/elaborate walk in cold frame. Do you have any pictures? I always recommend this idea to people but so far all of my clients have wanted something bigger to be able to grow fruit trees.
 
Jen Shrock
pollinator
Posts: 363
Location: NW Pennsylvania Zone 5B bordering on Zone 6
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You mentioned using stucco. How does it hold up in your enviroment? Do you have to use a special formulation to make it more durable, both on the exterior and interior?
 
Tim Malacarne
Posts: 226
Location: South central Illinois, USA
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Zach, I have photos somewhere or other, no idea how to post... We're pretty close to St. Louis, and have had some zero nights, yet even with my flimsy 4 mil plastic, the spinach and lettuce looks OK... We grow a variety called "Winter Lettuce" by the lady who mailed me some seed years ago. This stuff is very hardy in the winter growhole environment. I appreciate that it is mainly a holding action, and that not too much growth can happen, yet we harvest the spinach right along, and it's good! I built the growhole around 30 years ago of concrete blocks and then filled the cores. It's stout. Used cedar lumber for framing, still in service, but aging, as am I... My e-mail Bongo3@onemain.com
 
Jen Shrock
pollinator
Posts: 363
Location: NW Pennsylvania Zone 5B bordering on Zone 6
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Tim,

When you reply, look just under where you write your text and there is another tab for attachments. That should help. Would love to see pic's of your growhole.

Jen
 
Jen Shrock
pollinator
Posts: 363
Location: NW Pennsylvania Zone 5B bordering on Zone 6
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Moved my question over to a new thread in the sepp holzer forum.
 
William Bronson
Posts: 1413
Location: Cincinnati, Ohio,Price Hill 45205
18
forest garden trees urban
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The roofing is 3.5mm Solexx double walled polyethylene. It has an R-value of 2.1, 77% light transmission, 100% light diffusion, and only costs $1.55 per square foot. It is by far the most cost effective glazing solution that I've come across. It has a 10 year warranty, lasts 10-20 years, is as insulative as triple walled poly-carbonate, yet is only a fraction the price. Furthermore it can be lapped, meaning you don't need to buy H-channel and U-trim (an added expense of poly-carbonate). And it comes as a roll, reducing the cost of shipping and making it easier to handle and store. You have to order it through one of their dealers but it ships quickly and cheaply. I am one of their dealers and am happy to offer a discount for all the Permies out there, just let me know your on Permies at the time of order.


Thank You!
 
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