The Wofati Greenhouse movie excerpt - intro
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- Опубликовано: 27 фев 2022
- permies.com/greenhouse We wanted to install a greywater system so water from a kitchen sink could go to plants instead of a septic tank. Except those plants will be dormant in winter - so any funky sink stuff would just build up and be gross.
How about if we made a small greenhouse? Greenhouses are famous for needing more heat than homes - all that glass is a very poor insulator. Plus they can get too hot on a sunny day and kill
everything in the greenhouse.
Well, we have a lot of projects here doing amazing things to solve heating problems. So can we invent a greenhouse that never gets too cold or too hot? Maybe we can use some elements of Mike Oehler’s greenhouse design and some elements of our wofati design. And maybe a
few other ideas.
Our design starts with the general shape of Mike Oehler’s design from The Earth Sheltered Solar Greenhouse Book. He grew tomatoes in December, off-grid, with no heat of any kind, in Northern Idaho. The genius of his design includes 3 improvements over a traditional greenhouse.
(basic greenhouse)
Improvement #1: reduce the size of the air space with a trench
(a basic greenhouse with a trench)
Improvement #2: an earth berm on the north side (thus, some added
insulation and less glass)
(an earth berm greenhouse)
Improvement #3: most importantly, the 5 foot deep trench under the walkway.
(Oehler-style greenhouse)
I think that the trench adds a big dose of superpowers that most people overlook. If the deep ground temperature is a constant 50 degrees, then whenever the temperature in the greenhouse drops below 50, the 50 degree air from the trench will rise up & the colder air will sink down.
Before he died, I talked to Mike about another possible improvement:
Improvement #4: What if a copper pipe was blackened, shaped to follow the glass vertically and drop down to near the bottom of the trench. When the sun hits the greenhouse, the top of the pipe would heat up and act like a straw to pull cold air from the bottom of the trench. Eventually, the hot air at the top of the greenhouse would be pulled into the trench and warm it. I called it a destratification pipe. Mike agreed that this would probably help a lot!
(destratification greenhouse)
Improvement #5: A common farmer trick is to put 20 feet of well casing into the ground, then put a watering trough on top of that. When the outdoor temperature is negative 25 degrees (F), the water doesn't freeze. When the water gets cold, it cools the air at the top of the hole. So the 50 degree air from underground rises to the top & the colder air right below the trough sinks. There is so much air exchange that the water remains warm enough not to freeze. With this trick plus the previous improvements, maybe we can circulate enough heated air from the greenhouse through the pipe to get the temperature at the bottom of the hole closer to 70 degrees instead of 50!
(destratification greenhouse with well casing)
Improvement #6: Our wofati house design attempts to use heat from summer to heat a home through winter. We do this by berming dry earth against & on top of the structure and keep it dry with a membrane we call “the umbrella." We are still experimenting with these structures,
but so far they have had no freeze, even in our Montana winters. So let’s add dry dirt to the roof, the west side & the east side - and an umbrella to keep that thermal mass dry.
(wofati greenhouse)
Improvement #7: Our original mission was to design a year-round greywater system for a cold climate. In this case, “the problem is the solution”: greywater tends to be warm. If part of the greenhouse is dedicated to accepting greywater, then there is a constant stream of
warmth pouring into the greenhouse.
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a link to the full movie permies.com/greenhouse
When do you expect the movie to be released?
@@hugh3464 Part 1 has already been released. Part 2, the biggest part, might be ready in a few weeks.
It's much of the ancient tech of the Chinese greenhouse. Also Soviets dug trenches to grow citrus plants in winter. It worked but could not compete with low priced imports.
In Belgium there were 'fruit walls' which buffered heat.
The Chinese had straw mats that they rolled over the glass as soon as the sun set. That way they retain in the nights.
It's great tech
I find it interesting how Mike's house and greenhouse slowly progresed toward the design of the Earthship designed by Michael Raynolds.
Well, yeah, except for the tires and the cans.
There are similar designs in Japan country side too. And it is much like walipini too. Anyway thank's for sharing.
Very glad to see you are using Mike's book. We had fun putting that book together and I still love it all these years later. Sincerely, David Fairall. P.S. I don't live in Idaho anymore but Oregon. after a 4 year stint in the Middle East! 😁
Great summary of the innovations. Can't wait to see it in person someday.
Paul, you have such a soothing story teller voice. This video was very informative. Thank you for all you do.
It's a brilliant experiment and I'm sure some of these improvements will advance greenhouse design. I'd like to incorporate some of these clever features into my own greenhouse. But the overhead umbrella eliminates much light, and the growing area is small given the amount of construction. Only the heating is passive, not the watering or maintenance of the plants, so someone will usually still be visiting the greenhouse daily. I wonder if a a low-energy-input heating system greenhouse would be more efficient to build and grow in than a no-energy-input one.
Russ Finch has for decades been building inexpensive greenhouses in Nebraska that are large and warm enough to grow citrus trees, powered only by buried plastic tubing and a small fan at one end. I think it's $10 of electricity per year or less to heat a large greenhouse by that method, and that trickle of electricity could surely be powered by off-grid energy generation: wind, solar, etc. with a battery, maybe no battery if located near running water that can be used. Those greenhouses are much larger and let in overhead sunlight, but they don't freeze at -25°F. I think it gets -40°F out there. So while a completely passive greenhouse is an important proof of concept, maybe we're getting diminishing returns by going _totally_ passive, requiring a much more sophisticated and smaller greenhouse than one that uses a very small amount of power to heat itself (like a single small fan).
On the other hand, digging is a lot easier without having to bury piping over a large area, and that isn't possible in some places. I'd love to see some of these clever ideas in action, like the copper pipe passively accomplishing air transfer. I expect this design works. I have nothing to complain about when it comes to a greenhouse that works with entirely passive heating. There's certainly much to learn and innovations to pioneer and popularize here. It's been proven that much can be accomplished with windows on just one side, especially in sunny areas, as seen with Earthships.
I like both of these designs, my last Northern passive solar green house was zone 10a on a cold winter and 10b on a warm one. This is without anything but 8mm twin wall polycarb. Just a second layer inside for the two coldest months would have given it, easy zone 11++. But that greenhouse was defacto living space most of the time and the cost was around 15-17$ per sqft in 2018 prices. It would be nice to get the embodied energy waaaay down and costs down. A dirt floor would have saved several $ per sqft.
The copper pipe thing is a good idea, but not copper, a 2" copper pipe would cost a small fortune even in the 'before' times. And no move squat for air. But a 6-8-10" piece of drainage tile (black corrugated pipe) in place might work wonders. This is a great Idea I'd love to try.
I am with you, that a little tiny bit of 'active' can go a long way. Everything is diminishing returns it seems!
It looks to me like the placement and angle of the window in the wofati greenhouse is specifically designed with the low angle of the Montana winter sun in mind. You're letting in the majority of light in the winter, but blocking more of it in the summer when it would overheat things. Plus anywhere you have glass will lose a lot of heat overnight because of the poor insulation.
Russ Finch's design might depend greatly on latitude to work. His farm in Nebraska is around 42 degrees North, so even though its well below freezing he still gets above 9hrs of sunlight on the shortest day of the year. My location is 53 degrees North; id be worried Id go to great expense of landscaping and materials only to end up with a marginally more efficient greenhouse with poorer access and working conditions.
As someone would have to attend the greenhouse on a regular basis, a gravity generator would seem to be an appropriate source of power. (i.e. a heavy weight on a chain is connected to a _very_ high-ratio gearbox which turns a generator to charge the batteries that power the rest of the system. It is a very low-tech, cheap system that can be put together with (mostly) found parts. It can even be made automatic by having water pouring into a bucket be the weight, with the bucket tipping into a tank when it gets to the bottom of the chain, so the whole system will reset by a counterweight. ...or make it robust enough that someone sitting in a chair is the weight.)
Reminds me of Mike Reynolds Earthships
This just popped up in my YT feed, is a great intro to draw myself and others to the entire movie.
For the thermal air siphon, a copper heat collector, with a plastic pipe down to bottom of trench may more cost effective for daytime cooling, and a second heat collector buried in the soil, bottom of trench for nighttime heating to prevent freezing. Perhaps a Y fitting, and thermally actuated flap to take the top collector out of the loop at night, since with the 55 to 40 degree nightime differential convection flow will be very mild, and passing it through a cold top collector would slow it down. Daytime, I expect the top collector would easily hit 90 degrees, with the solar power (thermal gain) and a greater difference in temperatures daytime air flow would be significantly stronger.
For spring/summer a PV panel and fan would drastically increase the cooling capacity of this system.
I like the pipe idea. It would reduce the chance of forming a kind of an inversion airlock thing happening in the trench.
I just noticed the permies tag and I am one now too! While I was in the Middle East I earned my PDC under Rico Zook in a great little village in the Hashemite Kingdom of Jordan, the most water challenged country in the world. I was involved with a lot of others to help Jordan learn to "grow" water but had to go live in Israel, where we did the same thing there before coming back to the lower 48 in Oregon. Thanks again for these videos and your website.
I love the animation!
I love the experimentation and invention that goes on here.
That sounds like it is worth building.
Brilliant tips!
Exciting!!!!!
Fascinating!
I love it!!
Very cool.
This is a great idea, these are all really good improvements. There's one improvement I'd like to add which I'll call Improvement 0, because I think it comes before all these and IMO it the most important for anyone looking to grow food and live efficiently. Improvement 0 is taking advantage of the fact that humans like to live in warmth, and so do plants, so how about we combine these and live together and turn our house into a plant growing house, and train our minds to embrace that we should be living in greenhouses This is what I'm doing and its amazing, I'm growing 8 Banana trees and 3 Pinnapple plants in my Tinyhouse on wheels, which ia a greenhouse I live in. I'm building a RMH for supplemental heat, also using ground heat/geothermal, and the whole south half of the tiny home is clear twin wall polycarbonate. My Tiny Greenhouse is on a trailer so the North wall and roof are heavily insulated. But since the trailer is 2ft above the ground, I'm skirting the bottom sides around the trailer against the ground insulating it, and doig this effectively allows me to use the entire ground under the trailer as geothermal heating mass that will effectively do the same as having a North wall thermal mass. Additionally, I'll be insulating the ground out away from the trailer skirt about 3-4 ft to move the ground frost line that distance away from the ground under the trailer so cold doesnt creep in. The trailer is 8 ft wide, but the south facing Twin wall polycarbonate section is actually a 10 ft x20 ft addition built on the side of the trailer directly on the ground so I have 18 ft x 20 ft of ground geothermal mass available. I've got quite a few more tricks too..... this is just the beginning.
Additionally by living in your greenhouse you are increasing the CO2 levels and increasing plant yields.
These are great usable ideas. Heres my idea to add to these.
Maybe the use of aluminium foil or mirrors could spread the sunlight ànd heat into the rest of greenhouse or home.
Sounds very interesting. I'm looking into greenhouses and heating for a somewhat different reason than most. I breed rare tortoises, and plan to move north. So, I need to keep it a minimum of 70 at night, and a minimum of 85 in the daytime. In the end, I can't see any way around that needing supplimental heat in the winter to get that warm, but things like this can potentially offset the amount of supplimental heat I do need.
I love it!
I am usure how exactly to keep the earth dry without a complete capillary lock on the dirt, Possible but would turn into a large amount of membrane and even a small leak will eventually saturate I would imagine. Maybe you are lucky to have really sandy soils. Clays would be really tough without a physical moisture barrier of some kind I think.
The dirt roof will still want some insulation somehow, otherwise it could be a perma-loss for heat when you want it for 5 months out of year. even R5 would be amazing and probably do the trick. Lets keep the evolution going!
Great points. I would imagine some form of closed cell insulation with the membrane and then dirt on top.
good stuff
Looks like an Earthship style structure to me...
The grey water system is the deal breaker on being completely passive, I agree it’s a good idea to do it. Design looks good, I wonder how much you would need on top to be able to ditch the umbrella & do gardening up there too.
Grate explanation
Lost track of you since I built a RMH. I'm building a small earth battery greenhouse this spring not sure about incorporating gray water to the system. It already goes from the produce wash station to the Nanking cherry hedge. Best of luck. If you're road tripping through Iowa stop by. The RMH is awsome!
Goodeetens Produce Farm
Could bea great addition to our permaculture location here in Tasmania
Also what if it insulates the north, west, and east, wall with simple reflective insulation
I would reference the Chinese greenhouse as well
Alright digging a trench, but if it is not shored up, it is likely to cave in.
Interesting to know how the trench would work if the greenhouse was connected to a house.. since the house is warmer then the trench, maybe it would actually loose heat, since the alternative is to insulate and have tons of mass inside the greenhouse
...and, for even *more* passive heat, know that composting is exothermic, meaning it produces heat, more than 170F, if you aren't careful to keep it below that to avoid cooking helpful microbes! If you place your compost pile below the water tank with loops of HDPE pipe in the compost connected to it, as the water in the pipe heats up, it will naturally rise and warm the water in the tank.
Good idea, but in our climate which is a cloudy maritime climate in the winter and shoulder seasons light is limiting factor. Assuming you don’t have a supplemental source of electricity and light then your ideas were great other than the covering of the east and west windows, as you would lose a significant amount of llight and also solar gain. In addition, the Earth does not provide Insulation, but it provides thermal mass. As a result, this provides a thermal buffering mechanisms. This could be improved by adding insulation beneath and to the rear of the thermal mass.
I love this idea. It seems to me the piping would be too small to move a reasonable amount of air to make an effect. Was their a calculation for that diameter?
Black unpunched drain coil for doing the circulation cycle.
Much akin to using draincoil (behind glass enclosed box in sunshine; during winter) to heat houses when it is winter.
Fan assist for boosting transfer.
Can be coupled with water filled barrel in ground for either heating or cooling. Pump needed for max respones during peak heat and cool.
We live in Texas and extra hot climate we have several months of over 100-degree Heats on a daily basis the lows get down into the high 70s. Do you have any solutions for us? Will this greengouse still work in Texas?
I hope to build a wofati freezer soon --- that design could be of help to you.
Yet another of our community's efforts that appears perfectly viable as-is on other planets. Guys, we are nailing down lunar agriculture *by accident.*
Can I just come live out there and help out?
wheaton-labs.com/bootcamp/
Would you have to worry about radon with this?
just need some land to do this, i already have the windows and shovel
why not run the rocket flue through the trench. The question is how far could the flue go. Could it just go on horizontally to the end of the greenhouse. Plants like carbon dioxide.
Hey Paul my name is Bruce I contacted you a while ago I was curious I was thinking about moving to Bozeman Montana and maybe buy a small piece of land or something do they allow to build the like Earth dome houses on the property up there I'm just curious because you live in Missoula so you would probably know Wheaton Labs is in Missoula sorry
so easy to go from a greenhouse into a living space for humans. nevermind about the vegetables
so, making an earth ship without the home......
without the tires. add a trench. Add two wells. Add round wood timber framing. Add the umbrella. After all that - sorta.
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