Sustainable Energy: Thermal Banking Greenhouse Design

Sustainable Energy: Thermal Banking Greenhouse Design

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Steven Schwen of Earthen Path Organic Farm (Lake City, Minnesota) has built an innovative greenhouse that allows him to extend his growing season while reducing energy costs. SARE’s Farmer-Rancher Grants program provided critical assistance for Schwen in the beginning phases of his project.

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What do you think?


Written by Aleksandar

Video MakerContent AuthorYears Of Membership


  1. I live in Ottawa Canada. Can you tell me if you insulated the perimeter of the greenhouse with anything? You can buy waterproof insulation (closed cell) that you can put in the ground around the perimeter. This would save you a lot more energy than just blowing warm air under the soil, because the soil around the inside, nearest to the wall, would be more freeze protected. Would it not? I always read anything that comes along concerning growing things under glass or plastic.

  2. Why is it that it seems like every greenhouse video I look at, the person says, basically, 'We thought it would work, but it didn't so we had to change it.' Are greenhouses that buggy?

  3. Fundamental problem is that they aren't just blowing air through the pipes, they're blowing warm dry(er) air directly into the soil. He says during the first test that the soil dried out really badly, well no wonder. The air needs to go through a sealed pipe, not a perforated one. All you're doing is using a giant hair-dryer to remove the moisture from your soil. Not sure how they missed that. Other than that a well executed design.

  4. that is a lot of extra work that is not necessary, just dig your greenhouse in the ground. about 8 feet down you will have a constant 70 degrees (or so) year around summer and winter. you can also fun long lines underground like you did but you do not need fans Just an intake fan at the end of it sucking air in then it will naturally and slowly flow and warm up as it travels the long distance and have small outlet holes so it all can not come out the same place it will find an equilibrium to escape fairly evenly as heated air naturally rises. (and this almost never is even a needed step except for in the most extreme cold temps like alaska) Just dig underground and you are done. IF you really wanted to save that hot air you could run it back underground and heat up your chicken coop or into your house.

  5. I'm surprised that the link in the video 4:38: still works, (unlike where "Community Supported Agriculture is suspended due to lack of consistent help." and "Steven is weary of doing this farm solo, and since 2011 is looking to leasing or transferring the farm" Farming is hard work! This thermal-mass under floor heating was used by the Romans, (and though it is a useful technology, we need to automate the farming without reliance on petroleum horses.)

  6. Especially resonated with your final message. That how we typically measure "profits" in this country (with money alone) is pretty bankrupt. That we profit by our health; physical, mental, emotional & spiritual, by the nutrition we glean on all those planes being in right relationship with our bodies, Nature/Mother Earth, our community, ourSelves. This is the true profit. The one that benefits all. Thank you for reminding me of that. It brings me a lot of peace. : – )

  7. Water holds more than twice the heat of rocks and way ahead of soil so why not Aquaponics? Our 24' x 24' 2500g AP GH does amazingly well down to -20F and cost about $1000 to build due to good scrounging skills. Plus we get to enjoy trout whenever we wish. This is NOT rocket science and most of us do not get GRANTS.

  8. Double dug raised beds would warm the soil just as effectively as all this work you have done. Not sided raised beds, just double dug with shallow trenches directing and pulling water away from beds. I do not like using that row cloth at the bottom of your rows, Perched water table would be the main problem. Mixing sand into a soil does NOT help with drainage. The only way to improve any soil is by adding decomposed organic matter, to the surface of the soil. When adding NON decomposed organic matter to the soil you are putting most of the life in that soil to sleep, dormant or in eggs. Raw manure, bark chips, straw are non decomposed examples. The decomposers will go to work immediately to decompose. They need nitrogen to do their work. When they have converted non decomposed into decomposed then the life in the soil wakes up. Life in the soil has to have decomposed organic matter for energy. This needs to be taken into account when you start adding balanced fertilizers according to plant's needs. pH is a huge deal. Planting like needs plants together is huge. Rotating every year and leaving at least 2 years between tomatoes for instance being planted into soil that hasn't had any of the solanaceae family growing in that soil…for 2 years. Ventilation and drainage are far more important than that row cloth at the bottom of those troughs, for sure. 'Sumping' is a loose word we used describing losing larger gravel (larger pore spaces) we add to the surface, lost to the depths as fines sump up to fill larger pore spaces because weight is being applied to the surface. Landscape fabric was designed ONLY for this purpose, not weeds, not for losing top soil into the lower soil horizons FOR SURE. The row cloth is acting like landscape fabric in your mind, I think anyhoo. Remember, pressure and weight are not added to the plant beds, a bit for paths. If you had gravel paths, that row cloth would be properly used below the 4" of gravel to not lose that gravel. What skin are you using on your greenhouse? Artificial lighting? Warming the soil is in my mind is counterproductive. The sunlight warms the top 6" just fine. That is where 95% of all roots in this world are…your row cloth is impeding drainage just like a perched water table (think upside down as well). Let me know what you think…

  9. Interesting does it ever get way too hot in mid summer when all that heat stored underground combines with a high air temp in greenhouse? Do you then resort to release some heat outside.I wonder Is there any way the summer heat can be stored and used throughout the whole winter not just early winter and spring.

  10. Let me tell anyone reading this listening to this video…there is NO WAY you will be able grow your own food without a few years of practice. NONE. I am an expert and still learning. I am on sites answering questions about growing plants and IDing diseases, insects and blatantly dumb growing techniques…such as using garden soil in pots. Never is there an instance that that should be done until we are unable to get potting soil. We'd better know how to make our own soils for pots. We'd better know how to manage our local garden soils. We'd better know how to collect NON GMO seed to grow plants in our garden. We'd better know the basics; stuff like 'fertilizer' is bad…(omgoodness), hugelfugegel (spelling) beds, 'no till no dig' type gardens…epsom salts as fertilizer? All of these things are wrong. Period. Take a Master Gardener course through your nearest Cooperative Extension Service! In one year you might be able to grow your own food! If you think you will be able to grow food to survive when you've never grown food at all or had success with plants? Forget it. It is not a tough thing…but our system does not teach botany and agriculture in the first 12 years of school. At all. If you think we are in some global warming thing you are seriously behind in information and seriously badly informed to not see this CO2 thing is pure crap. Check out John Casey's videos, they are all pretty much the same and kept simple. He is credible. I am no damn believer in magic, religion, money, haven't been brainwashed by tv and I am way over half a century old. 2 college degrees I paid for myself not by mommy and daddy, and plenty of life experience, continuing education and I am a major reader.

    Now imagine if the whole world adopted these ideals..
    the poor; hobos; street dwellers and the homeless could all at the same time go into business for themselves as well as others.
    shelter food family and work all in one spot.
    what's gonna happen humans when the genetics of your food flora and fauna are so corrupted that it is poison to your body and u wither and die

  12. Interesting greenhouse, but I just don't see why you wouldn't use fluid instead of air…Some kind of water storage tank which absorbs solar energy and then a pump instead of a fan which circulates the hot water through radiant pipes under the beds. You could even have a supplemental boiler attached to the water storage tank in case you need it certain days. Using air just can never be as efficient as water to store the energy.

  13. I have a few questions: Why is schedule 80 PVC being used? Is the Glazing or glass being used really effective at not transferring cold into the greenhouse at night or overcast days? Have you considered butterfly valves in the underground piping to balance the system like an HVAC system as opposed to what you have ( it was a little tough to really see exactly what you had)?  It seems 40k is a bit much for a greenhouse for me, I don't have grant money. I did like the wood construction. A guy with a hobbyist sawmill could easily cut wood from his land to offset that cost. Good video. It really got me thinking a good bit about how I want to build my greenhouse.

  14. Great design! I am trying to keep my miniature greenhouse warm into winter with various methods but I haven't thought about heating the soil this way! Thank you.

  15. Could not evaporation absorption refrigeration be used to cool a green house in the summer. Induction or magnetic or solar vacuum tube water heating for the winter that can also run TEG's to keep capacitor banks and batteries charged? NOVARTIS

  16. In a traditional Green house could you not run 10 inch construction pipe under ground to each corner with the intake at ground level then have the other ends at celling level with booster fans to circulate the air to keep everything at an even temperature? Or even have a regular house A/c unit keep the temperature just perfect to grow what ever crop your trying to propagate?

  17. This design could all be ran off ducted systems to control temperature so there would be no need to vent any heat or any cold. Solar vacuum tubes used to heat water and power TEG's with capacitor banks and even solar panels could run all these systems. All self contained stand alone green houses to produce food and medicine. Is this a good idea?




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