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Thermal mass green house.

Thefishguy77

Thefishguy77

Part time dumbass
Joined
May 19, 2020
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271
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U.S.S.A. (Washington St.)
Ok so I about done clearing the area for my new garden and thermal greenhouse. I have been watching all this winter amd last and my chosen spot gets good winter sun. Since it a thermal mass green house I will only have one side with clear multiwall polycarbonate, the rest will he insulated walls and roof. I am no debating on size. I have 6/ 4x8 clear panels so 192 sqft on one side of the roof. The roof will be roughly a 45deg angel on the south side. I was thinking of a 4/12 pitch for the north side. My original plan was to use 5 4x12 sheet but they were significantly more expensive per sqft due to shipping. So instead of being limited to 20’ wide I can now do 24’ wide.

My thoughts are dig it around 2’ in to the ground, assuming I can get that deep without hitting water, and have the front wall around 2’ above grade for a total of 4’ on the front wall before the south side roof begins at a 45deg slope.

As someone who has never built or used a real greenhouse I am
looking for suggestions. My current small cold frame against the house has not dropped below 40 this winter keeping my dwarf citrus happy. By all accounts this new green house should stay warmer than my current small one.
So nothing will go directly in ground, figuring from the research I have done a combination or benches for trays and pot & raised beds for some other plants seems to be the win. So how big is too big and how small is too small? Square, rectangle, doesnt matter. The bigger it is the harder to keep warm but more room to grow. The smaller its easier to warm but less space. Exterior will probably be steel roofing to help reduce maintenance.

Anyone here built one? Or worked with normal green houses to help my with size layout?
 
Not much help but..

Make entering and exiting easy. Things that stay inside during the winter will want to be out during the summer. A small potted tree per say will be much easier to move on a dolly castor system than by hand.
 
Mr Stubs said:
Not much help but..

Make entering and exiting easy. Things that stay inside during the winter will want to be out during the summer. A small potted tree per say will be much easier to move on a dolly castor system than by hand.
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To expand on this idea, you can put down two angle iron tracks and build your benches with v groove wheels. Then you can roll all the benches/racks right out a big door on the end easily.
 
Mr Stubs said:
Not much help but..

Make entering and exiting easy. Things that stay inside during the winter will want to be out during the summer. A small potted tree per say will be much easier to move on a dolly castor system than by hand.
Click to expand...

Was going to make it so I could just take the south panels off during the summer. Otherwise shit will cook. We are mid to upper 80’s all summer with usually a month or 2 in the upper 90’s.
 
All I can say is, jealous. Id love to build a greenhouse like you're describing.
The hoop house I built last year worked great with auto opening windows in each end. I posted some pics in last year's gardening thread.
 
What are you using for thermal mass (per thread title)? It could be your cold frame has managed to stay 40+ due to heat from the house.
 
Microtus said:
What are you using for thermal mass (per thread title)? It could be your cold frame has managed to stay 40+ due to heat from the house.
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Earth piled up the outside against the steel siding. 6x6 timbers. Similar to a pole barn. Then insulate the west, east and north walls along with the roof. Yes the cold fram is staying warm with the house for sure. It is also ghetto insulated on the “gable” ends, and the lids just lift off. Other people around here do it and they maintain mid to upper 40’s when its in the teens outside for extended periods.

If I end up needing more mass I have an endless stone pile I could probably do something cool with. I would live to do ICF but we are trying to keep costs down with my work being at about 50% vs last year. So Am using milled timbers and lumber. Doing it very much from the land when possible. Haven't found a polycarb tree or a steel siding tree yet so I gots to buy those:flipoff2:.

It is going next to a new garden as well so will be elk resistant fenced all around. Fucking overgrown dogs.
 
SILLA said:
I've put a few of these vent actuators on and they kick ass. No electricity needed. I replaced some worm gear electric actuators with these and haven't looked back.

https://www.amazon.com/Agriculture-S.../dp/B0036E58H2
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Those are bad ass. Thanks for sharing.

Do you know if they make smaller versions? I grow bonsai and have been thinking of making a very small green house for them, but I live full time in a 5th wheel and everything has to be small, collapsible and easy to move/store, or disposable.
 
Thefishguy77 said:
I would live to do ICF but we are trying to keep costs down with my work being at about 50% vs last year.
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icf still has the "green tax" on it
concrete itself is way cheap

actually, since you mention a rock pile, why not mortar them together into the underground portion of the wall? Masonry isn't hard so long as it ain't gotta be pretty.
dunno how well steel siding will hold dirt back, def. do 2x6 girts on like 12" centers
 
I believe just piling dirt around the non south facing slides of the greenhouse would work more as insulation v thermal mass. Granted, the better you can insulate the greenhouse the less thermal mass you are going to need to maintain temps. If you can get down to 5 feet without being in water then you can tap into the "big" thermal battery, think Walapini. Building thermal mass inside a greenhouse is most commonly done with large barrels of water.

Lots of information on Ceres site and Permies if you want to spend some time digging for it.

Ceres greenhouse roof and glazing angles. https://ceresgs.com/whats-the-best-r...o%20reflection.

I had plans of building a Walapini when I moved to Michigan but we ended up buying a house basically in a cedar/tag alder swamp. The greenhouse in the snow is a nice read/watch.


https://greenhouseinthesnow.com/
 
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Microtus said:
I believe just piling dirt around the non south facing slides of the greenhouse would work more as insulation v thermal mass. Granted, the better you can insulate the greenhouse the less thermal mass you are going to need to maintain temps. If you can get down to 5 feet without being in water then you can tap into the "big" thermal battery, think Walapini. Building thermal mass inside a greenhouse is most commonly done with large barrels of water.

Lots of information on Ceres site and Permies if you want to spend some time digging for it.

Ceres greenhouse roof and glazing angles. https://ceresgs.com/whats-the-best-r...o%20reflection.

I had plans of building a Walapini when I moved to Michigan but we ended up buying a house basically in a cedar/tag alder swamp. The greenhouse in the snow is a nice read/watch.


https://greenhouseinthesnow.com/
Click to expand...

Thanks for the reply. My original thought was 5 feet plus and I had what I thought was a good spot for it. But it gets decent sun 8 months a year and zero sun The 4 months a year I need it So that area is probably going to be a root cellar now as I already have 3’ earth walls on 2 of the sides and can dig down another 3 feet easily in that area.

Back to the green house. I have heard of water in the green house for thermal mass and that does work and am thinking about that aspect. I would keep the water heated personally as water while it makes a great thermal mass it also can take a long time to heat back up. Thais would probably involve some sort of solar power, easy enough with some aquarium heaters on timers and a few batteries. I have a decent history or large scale professional aquarium maintenance, and have seen setups like this in the past at some previous clients homes.

My other option for thermal mass is CMU’s mortar together and filled with sand on the inside. They come up free all the time around me from people buying old trailer homes and R&R them for a new manufactured home. Easily can find 30-50 of them at a time. Many people use them to skirt their older manufactured homes after the vinyl dies. I see them wrapped tight in hardware cloth and then CMU around them stacked filled with sand and capped with pavers set down on them.


Either way. Hopefully I will have all the logs cleared from the new area today. Didnt get it done yesterday due to life, but still had some good time with my oldest teaching him about using the backhoe and staying clear of pinch points and shit like that when skidding stuff. He is getting damn good on the controls so its nice being able to have a helper when I rig stuff to pull, huge time saver. He doesn't get to drive unattended yet. And when he get bored he gets a hatchet and chops on a stump. I swear that never gets old for him.


Edit: That page was a good read and I think I am going to buy that book. Looks like they mainly cater to pot farmers with all the cannabis greenhouse stuff on the page:lmao:. But great info on the roof angle. So far due to snow I think 45 degrees is my optimal angle and I know snow will slide off that especially if its not a frozen surface. I have watched a ton a Walapini videos and they look amazing. I hust dont have the ground depth when I have the sun. I am honestly thinking I can do a lot of earth around at least the North and West sides. Now thinking about using a heavily insulated wall, 2x6 studs staggered on 2x8 sill and top cap to stop the thermal bridging. on the east side and that will be the “gable” ends in the garden area.
 
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I think you should dig a 3' deep test hole in that location and see when you hit clay or rock, and figure out where your water table is gonna be before you commit any more time or money to this project.
 
For thermal maas make a water heater out of black pipe and circulate it to the storage containers.
 
Squamch said:
I think you should dig a 3' deep test hole in that location and see when you hit clay or rock, and figure out where your water table is gonna be before you commit any more time or money to this project.
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Thats the plan. 4’ is about as deep as I can possibly get and I know I need a foot or so above the high water mark before its safe. 2’ is solid safe. Currently clearing logs out of the area then I will have a final lay of the land. Had 8 trees tipped over and currently i have a fuckton of branches and other shit I need out of the fucking way!!!

Fawk I wish I had a thumb on my backhoe. Adding a manual one is going to have to happen.

Thanks for all the replies so far.
 
Ceres just added the cannabis side of things ie a market to exploit. A ghat system would be the cats meow for passive heat but if you can't get the depth due to water it's a mute point. There are other ways to heat a greenhouse though. Mass rocket stove, composting, water or blocks, etc. Hell, I think Gary did a write up around 20 years ago for a passive heat exchanger for his work shop that was little more than a black wooden box with some glass. Sniff around Permies a bit.
 
Microtus said:
A ghat system would be the cats meow for passive heat but if you can't get the depth due to water it's a mute point.
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Use the ground water. Drive a well point about 10 ft down. It should be a constant 50°F-ish. Circulate it for temp control then drain it back into the soil at another point, maybe a gravel dry well to avoid freezing at the surface. An open loop gaht instead of buried pipe loop.
 
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If I built one it would be straw bale construction. Look it up if you don't know what it is. Otherwise, I've seen some cool soft side ones that use composting material to generate heat.
 
rugger said:
If I built one it would be straw bale construction. Look it up if you don't know what it is. Otherwise, I've seen some cool soft side ones that use composting material to generate heat.
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I have seen straw bale construction before and am not sure how well it would work around here. Anything straw pulls in the elk. If a hay or starw truck stops on the highway there are a dozen plus elk eating off of it by he time the driver get back. People that put straw down for erosion control have it destroyed the first night.

I think I am at the point where I have decided to mortar large stone together to get my walls under ground, with footings poured where needed.
 
Thefishguy77 said:
I have seen straw bale construction before and am not sure how well it would work around here. Anything straw pulls in the elk. If a hay or starw truck stops on the highway there are a dozen plus elk eating off of it by he time the driver get back. People that put straw down for erosion control have it destroyed the first night.

I think I am at the point where I have decided to mortar large stone together to get my walls under ground, with footings poured where needed.
Click to expand...

The straw is covered by stucco. And, plenty of those structures have been constructed in Colorado. If elk are getting into it then it's hay unless they are somehow using the erosion control straw for bedding. I wouldn't put it past them to play with it. Straw is not digestible. They won't eat it nor will anything else. That's the appeal of it. Keep it dry and it may last forever.
 
rugger said:
The straw is covered by stucco. And, plenty of those structures have been constructed in Colorado. If elk are getting into it then it's hay unless they are somehow using the erosion control straw for bedding. I wouldn't put it past them to play with it. Straw is not digestible. They won't eat it nor will anything else. That's the appeal of it. Keep it dry and it may last forever.
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You lost me at stucco in my climate. We are way to wet 6-9 months a year Seen to many stucco houses in my area and they all have massive issues. So now that I completely ruled out stucco wait for my next thread on how to do stucco yourself :lmao:
 
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