I am a missionary working in Siberia, Russia. I finished an earth sheltered greenhouse this fall and have had some encouraging observations to share. I wrote the following as a FaceBook post but I really wanted to share it with you all since I'v learned so much from these forums and wanted to sort of pay it back. Maybe someone building a greenhouse/ barn could find this information and my stats useful!!
We have an underground (earth sheltered) greenhouse/barn structure thing that I am hoping will prove very effective in year round food production. The barn is about 108 m(2) (1,162 sqr ft) and the green house is about 81 m(2) (872 sqr ft) the combined floor space of the two halves of the structure is about 189 m(2) (2034 sqr ft). Bare with me!!
I've been collecting data this year on its thermal performance. I intended to heat the greenhouse with two Jean Paine style compost piles. Each of these piles is capable of producing between 9-12kw/h of heat energy for between 16-20 months. I had assumed that I would need two such piles to keep the temperature at 10 C (50 F) in the coldest winter days of -50 C ( -58 F).
Due to technical failure of my chipper I was unable to assemble these compost piles. I was really disappointed about this BUT have had the opportunity to gather data on the performance of the structure without any outside heat source.
Currently, without any external heat source, at -42 C (-43.6 F) outside temperature the Greenhouse was -14 C (6.8 F) and the barn was -5 (23 F)!!! This represents an average of about 7.2 kwh worth of heat energy coming from the surrounding earth and the animals!!!
The really cool news is this: The thermal performance of the barn/greenhouse structure as observed this winter is such that, after running the numbers on my thermal model of the facility, it is rather conclusive that 1 Jean Paine pile should be more than enough to keep the greenhouse at 10 C (50 F) most of the time and during extremely cold nights such as - 50 C (--58 F) the greenhouse temperature should be no cooler than a balmy 7 C (45 F)!!
NOTE: normally the barn would be MUCH warmer however the design is such that it uses the heat from the barn to warm the greenhouse.
NOTE 2: If you think this is not a big deal then consider how warm an above ground hoop house would be on a cloudy windy day with -40 temperature outside for days on end! Don't have a hoop house? How cold would your house get unheated??
Hopefully we will be using this greenhouse this spring and if all goes well then the underground greenhouse/barn structure concept will become a central piece of our tent making model for rural pastors in small villages!
Here are a few pictures of the 3d computer model i made of the greenhouse barn structure. I'll upload some pictures of the real thing later.
I have learned volumes about what to do better next time and the next Underground Greenhouse barn I build will be a lot better. In fact I am optimistic that with some design modification and a few other tweaks I could get a 2 C (36 F) greenhouse temperature at an outdoor temperature of -50 C (-58 F) WITHOUT ANY EXTERNAL heat, compost or otherwise (not including the sun, of course). This is extremely ambitious but I think possible and affordable!
Thanks to Mike Ohler, Sola Viva (I don't know the lady's name), Jean Paine, and the Permies Forums
Thanks to Dan Rulison and Jordan Jonas for A LOT of work put into this structure!
Thans to a lot of other folk who donated time and man power along the way!
Thanks to two generous financial contributors who made this experiment possible!!!
Give a man a fish and he eats for a day, teach a man to fish and he eats for a life time!
Nick, are you familiar with Elliot Colemans 4 Season Harvest?
His idea is not to grow plants in the winter, just harvest them. That's the theory, anyway. I've not been able to make it work for me because I'd have to plant spinach in August/September and it's just to hot in the hoophouse for that.
My project thread Agriculture collects solar energy two-dimensionally; but silviculture collects it three dimensionally.
Here in the mild climate of Vancouver Island, I wouldn't heat a greenhouse during the coldest months. A March start up is perfectly adequate for producing vegetable starts. If you look at the little bit of production that is realized in winter, it may be less valuable than the extra feed that the animals consume when their body heated air is being diverted to the greenhouse.
Alright, Sorry everyone who asked for photos. I had some internet issues and then it took me a bit to figure how I was going to upload a decent amount of pics to the forum, but I think I go it figured out!!
Those pictures were from the construction and then from this February, early.
These photos are from early March ( a few days ago).
I cleaned some snow off of the polycarbonate and It REALLY makes a difference. I also took some photos showing where the earth berm was not deep enough and where walls would have really benefited from just a few more feet of dirt or a PAHS umbrella. I also show here the problem with condensation that I did not count on at all. Having to scrape off layers of ice from the INSIDE of the greenhouse to let the sun in!!
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
When temperatures were consistently low I had a pretty solid 20 to 25 C degree lead on the outside temperature. However, it Never Got colder than -18 C (-0.4 F) in the greenhouse. Barn temperatures were always around zero C (freezing) or slightly above freezing.
I also have a root cellar underneath the greenhouse that is consistently a few degrees above freezing until late January when things got real cold (-40 C and F) after which it has been pretty consistently -2 C (28 F).
So some sample temperatures
2C 35.6F -17 C 1.4 F
-12C 10.4 F -35 C -31 F
-13C 8.6F -40 C - 40 F
Towards the end of the winter it seems the available heat in berm and earth around the greenhouse had been depleted because the temperature difference dropped.
-19C 2.2F -40 C -40 F
-12C 10.4F -32 C -25.6 F
These temperatures are for the inside of the greenhouse in the morning before dawn. This has allowed me to demonstrate that in order to heat the greenhouse I will need about half of the heat energy as I had previously thought necessary. So hopefully I'll be able to keep workable temperatures in the greenhouse using only 1 Jean Paine style pile.
Right now the greenhouse is not heating up as quickly as I had hoped. I think this is partially due to the ice build up on the inside (frozen condensation coming in from the barn. AND I think this is due to the thermal flywheel effect which worked so well in the fall is working against me here.
Some ideas that I'll probably implement in the next greenhouse/barn building. The hayloft does not do so well in keeping in the heat. Make the barn a true wofati structure by not having a hay loft above and simply burying the whole barn portion of the structure. Because the back of the greenhouse extends above the floor of the hay loft (or the ceiling of the barn), there is a whole section of greenhouse wall that is exposed to very cold temperatures with very little to no insulation. Bad design. By berming earth and using some insulation on this portion I think a LOT of heat loss could be avoided.
Also I need a steeper angle of glazing. Does any one have a definitive idea on what angle the glazing SHOULD be at?
I also need to work harder to berm thick to the corners. I also want to make some canvas "curtains" to put on the outside of the glazing from evening till morning to help keep heat in and remove them during the day to let the light in. I also should have built a cob wall between the greenhouse and the barn instead of just a board wall. This would provide a little better insulation for the barn as well as give the greenhouse some thermal mass that can be directly heated from the sun. All in all this project has functioned better than I hoped but the experience has shown me that it can function a LOT better IF designed somewhat differently. I hope to get a Jean Paine pile going this summer to use the Greenhouse this fall.
As to angle for glazing there's a formula in an old book around here somewhere. Ought to be out on the net too. Has to do with your particular latitude... I have a 30 year old, or older Rodale Press book, The Solar Greenhouse Book, I think it is...
What latitude are you? I am over in Ak with similar climate,I think. I am wanting to do something like this but don't have the animals...Maybe just a true three season greenhouse. (We tend to have only spring and winter here)
I'm at 57.61 N 96.7 E. No permafrost yet. But cold as anything in the winter. I'm really trying to eventually get my growing season from March 1 - Dec 1, instead of May 20 - Sept 10! So 3 season as well!
I think we can do it too. I'm just beginning to wonder if a RMH might not be better than a Jean Paine pile. We'll see.
Hi Justus; Awesome job ! Your climate is much more extreme than mine in north western montana, but I have had excellent results with a rocket mass heater in my above ground greenhouse. -10 F outside with wind, no fire from 11 pm on and temp at 6 am 41 degree !!!They use a lot less wood than any other method for the heat gained and cost can be very reasonable. This might be a way to help keep your condensation problem under control as well. The mass can be used as a raised heated starting bed for the starts. Spring is finally approaching here, with night temps in the +25 F and day temps in the 40s I only light a 1-2 hour fire in the early am , then out all day relight 8-9 pm for 1-2 hours and i have 50+ F in the morning! The sun is finally high enough to produce enough light that things are really greening up in there! Good Luck with your project . Tom
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Fantastic job! and some excellent points to take not of - especially the condensation issue.
I recall Ben Falk mentioning that the Jean Paine pile works great but is a nightmare to de-construct in the spring. You have a large pile of consolidated compost set around a few hundred feet of coiled piping. Separating it all out was a major mission.
It would serve you well to think about ways to mitigate this before you build it. Maybe a different piping configuration, or the coil made up of removable sections?
I assume that you want a steeper roof angle to keep the snow off?
Solar panels are typically inclined between 65 and 70 degrees in the winter in Canada for this reason. From a mountaineering perspective, anything over 30 degrees is considered avalanche country. I would personally go for 45 degrees at a minimum. It looks like Thomas' greenhouse has a 45 degree roof. There is a bit of snow accumulation but not much.
I am at 47.25 latitude north and I find vertical glass works fine in the winter and has less overheating in the summer.
For your existing structure I would recommend extending the glazing to the peak of the hay loft with a reflective wall on the south side of the hay loft to reflect light down through a lighter layer on the caling of the greenhouse. This empty airspace would possibly prevent the icing problem. A cob wall between the barn and greenhouse heated on one side by a RMH and compost pile on the other side. Take advantage of all that animal manure and beading all winter.
That is awesome! I would like to know how a much smaller greenhouse would perform? My partner started to build a half sunken one, but didn't finish no time (one day). However this one floods in heavy rain. Here it gets only to -5C and this is considered as cold!
I contacted you a while ago about being a case study in our greenhouse book on energy-efficient solar greenhouses... Glad to see the project came along.
I agree with some other comments, that the roof slope looks a bit shallow to collect sufficient sun in the winter (given that the angle of the sun is quite low at that latitude). Did you do any calculations on that?