Mike's passive solar greenhouse design/build

@Mike, think about how you might be able to repurpose the space before demolishing it -- you might be able to make that space into something like a planting station and storage or something.  That said, it still might be better to rip it out and use it for a more beneficial purpose.  I had made a mistake like that on my own project and regret it to this day, but that is a LONG and preferably private story for offline.

Mike Haasl wrote:.

I also picked up ginger and turmeric from our organic food store and have them tucked around in the beds.  We've saved all our pineapple tops and have many of them started as well.  I also realized that the piper nigrum seeds look remarkably like peppercorns.  Since none of the purchased ones came up, I planted about 50 peppercorns in the beds.  Hopefully at least one will grow.  Lastly, I found a vanilla orchid at the local greenhouse/florist and brought that home.

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I think I'm a bit jealous about these that you are attempting.  I've heard black pepper takes awhile to sprout. Ive gotten several pineapple to get growing but not to fruition. And OMG a real vanilla orchid? Are you kidding me?  I want to try this eventually but know I will have to have a greenhouse to attempt properly.

Please DO keep us updated on everything greenhouse!

From the top posting: One or both sides will get shredded hay mixed in to increase the Nitrogen ratio.

People should be aware that farmers growing hay use a spray application of a chemical that will even go through a cow's system and still be toxic to plants.

Make sure that your source for hay does not use chemicals (I've forgotten the name for the common chemical they use), but that the crop has NOT been sprayed with chemicals. That chemical is very, very detrimental to plants. IF in doubt ask your source people to verify that the hay is herbicide free.

Had to stop and check on that name. It is Grazon, however, that is only 1 of 3 main herbicides that are commonly used.

BUYER  BEWARE !!!

Boy have I been delinquent in updating this thread.  Sorry about that!

I removed the compost bin.  Related to Jesse's concerns, I ended up using garden clean up materials for the "greens" instead of hay.  It didn't work.  When removing the bin I left the platform above it in place and supported it with a post and beam.  That eliminated catwalk modifications and the whole job was much easier:




The biggest project for the summer was building an Active Heat Battery.  I don't have it running just yet but should soon.  I know that system won't keep the greenhouse above freezing but it might keep the minimum temp at 25 instead of 20.  

I will rig up a temporary internal greenhouse under the platform for this winter to keep the potted plants alive one more year.  I have room to plant one or two of them in the ground around the edge of the temporary greenhouse (by the banana).  So in future years I might have a couple citrus in the ground, a winter warm area and the rest of the greenhouse will just have to handle going a bit below freezing.  Time to get some plants that can handle a touch of freezing.  

This summer I had a huge butternut squash volunteer covering about 400 square feet, carrots, jalapenos, a tomato, passion fruit, swiss chard, birdhouse gourds and snap peas growing.  Peppers once again had horrible aphids so I think those aren't destined to survive in my greenhouse.  The carrots are about ready to be harvested as are the butternuts.  I transplanted some kale from the garden and it's doing well.  

I need to get better at growing food in this greenhouse.  I've been in a bit of a holding pattern waiting to see if I can keep it above freezing.  Time to just move on and pick other tree/shrub crops that can live in it.  

I think the curved design is great - both for strength and to allow more light inside.  Also for shedding snow.  If you would please darken the handwritten lettering in your diagram it would make it so much easier to read your drawing.  

I'm working on some cold climate greenhouse designs myself. I would love to know how this turned out.

Good point, it's time for an update!

I've given up the idea of compost heat (within the greenhouse).  The way I did it did not lead to any appreciable heat but it did give off gasses that made me wonder if they were healthy.

I put in the Active Heat battery system (per the above update) but neglected to protect it well enough for a cold night (12 degrees lower than forecast) and the radiator split open.  I soldered it up a week ago and it's now ready for action.  But then I found that it would take a tremendous amount of antifreeze to keep the system from freezing at 20F.  

So my current plan is to move the heat battery into the area where the compost pile was.  That area is also closed off as a mini greenhouse for the tropical plants.  With a tiny electric heater.  So the barrels of water will stay above freezing in there.  I finally figured out if I reroute the heat collection piping I can keep all the liquid within the mini greenhouse and avoid any antifreeze.  But it will take more work to implement so that might not happen before the coldest part of winter is past.

This week is going to be pretty cold (-20F at night and 0F for daily highs) so I'll see how cold the greenhouse gets at night without the moveable insulation.  My guess is around 20F.

I'm planning to plant trees in the ground in the greenhouse this summer.  Figs, peach, pawpaw, almonds, etc.  And also use the greenhouse to extend my growing season.  I struggle mightily with aphids on peppers so I haven't done well with them the last two years.

I could elaborate, what are you interested in Patrick?

Mike Haasl wrote:Good point, it's time for an update!

I've given up the idea of compost heat (within the greenhouse).  The way I did it did not lead to any appreciable heat but it did give off gasses that made me wonder if they were healthy.

I put in the Active Heat battery system (per the above update) but neglected to protect it well enough for a cold night (12 degrees lower than forecast) and the radiator split open.  I soldered it up a week ago and it's now ready for action.  But then I found that it would take a tremendous amount of antifreeze to keep the system from freezing at 20F.  

So my current plan is to move the heat battery into the area where the compost pile was.  That area is also closed off as a mini greenhouse for the tropical plants.  With a tiny electric heater.  So the barrels of water will stay above freezing in there.  I finally figured out if I reroute the heat collection piping I can keep all the liquid within the mini greenhouse and avoid any antifreeze.  But it will take more work to implement so that might not happen before the coldest part of winter is past.

This week is going to be pretty cold (-20F at night and 0F for daily highs) so I'll see how cold the greenhouse gets at night without the moveable insulation.  My guess is around 20F.

I'm planning to plant trees in the ground in the greenhouse this summer.  Figs, peach, pawpaw, almonds, etc.  And also use the greenhouse to extend my growing season.  I struggle mightily with aphids on peppers so I haven't done well with them the last two years.

I could elaborate, what are you interested in Patrick?

How much luck are you having with the tropicals?

I have been contemplating some designs for an attached greenhouse in a very similar climate. I would like it to be as low energy use as possible as our place is off the grid. So as much passive heating and insulation as I can muster would be the thing. So my current plan is a vertical style greenhouse kind of like the attached example (although attached to the south side of the house). The version I had in mind is a bit taller and sunken down to below the frost line as well (so about 40"). Reflective insulation on the inside of the side walls and the inwardly angled top portion of the back wall. The rest of the back wall would be painted a dark matte black. I was going to utilize a scattering of dark rocks as well as the black rain barrels on the north side of the wall. It will have be a vertically layered situation. For the "windows", I was thinking corrugated polycarbonate or some real heavy clear plastic for the outside layer, with a couple of additional layers of 6 mil plastic sheeting behind it. So 3 layers (heavy duty on the outside) with maybe about a .5" gap between them. There is also a small pond that would be just outside of the greenhouse area. So I was considering ways to bring that inside of the greenhouse a bit. A neighbor has a trout hatchery and I am hoping to utilize the pond to irrigate the greenhouse somewhat for a small aquaponics sort of setup. We are also going to utilize the Chinese greenhouse blanket over the 'windows' at night thing. If all that fails to keep a moderate enough temperature, which it probably will when it is hitting -20 to -30f, I was also thinking about some radiant heating from a wood boiler. Either an exterior boiler or from the boiler attached to the wood stove. Although the latter is also being used for showers, cleaning, probably radiators, etc. so more likely an additional small external boiler somewhere. Anyway, all these thoughts are hypotheticals. We won't start building the greenhouse until much later this year at the best. Next year is more likely. I am just trying to get a good plan in order for a really super efficient greenhouse. The goal is to be able to use this one to grow plants that need more warmth year round. It would be awesome to get squash and tomatoes in the winter still. We are going to build a more standard high tunnel sort of deal a little further off from the house as well but that is going to be mostly just for getting things started and for veggies that are far more cold tolerant.  I'll have to sketch something up at some point to make all that more clear but I would love to hear your experiences with some of this stuff and your thoughts.

Well, the tropicals are surviving.  I'm sure a real grower would have them in much better shape than I do.  I got 7 lemons this year though...  

I think the biggest struggle for folks in our climate is temperature (lows and highs) and sunlight.  With the photo you attached, especially if it's taller, it will heat up really well on a sunny day.  Mine can easily hit 100F inside on a sunny January day when it's 0 outside.  So the smaller the volume and the greater the exposure to the sun, the worse the problem could be.  Plants that are barely making it through the night at 40F don't seem to like it that warm.

I'm sure mine would do better if I could plant them in the ground.  This year I will also plant my lemons and maybe another citrus right at the edge of my mini greenhouse.  Then they can have roots in the ground, can be in decent sun in the summer and yet I can wrap them into the mini greenhouse and help them survive winter.  I should take some photos of the mini greenhouse set up...

With sinking down 40", don't forget the pile of snow that will also be on that south wall.  With low angle sun and no snow, you may not get sunlight to the floor in winter.  With 4' of snow piled at the base of the glazing, the sun is blocked for much of the growing area.

Black is good for absorbing heat.  White is good for reflecting light to the plants.  I went with white but there are many ways of thinking.  I avoided the barrels of water painted black mainly because I thought they'd be in the shade of the avocado trees all the time.  No sun on barrels = less heat storage.

Layers of poly and plastic sound good to me.  If you have the twin wall poly on the outside it should stay flattish.  The poly will sag as it heats up but in your case it would sag away from the poly maintaining an air gap.  Two layers of poly may sag and touch or the inner one may sag more and it'll be fine.  Limiting light with that many layers could be a problem.  I believe they make 5x polycarbonate panels.

If you can do the Chinese Greenhouse blanket you could skip some of the poly layers.  A good insulated blanket would really help the situation on cold nights.

Regarding the pond...  If the pond is inside and connected to the pond outside, I think it would sap away a lot of heat.  And be hard to build a foundation in that area.  A pond totally inside should work.

Squash and tomatoes might hold their fruit into winter but I'm thinking you'd need to add light to keep them fruiting past October.  Maybe I'm wrong, I don't really know.

Good luck!

Your greenhouse sounds amazing. Yes it gets pretty cloudy and dreary in the winter and spring. I have a fig, and a lemon tree in pots and I bring it inside the house overwinter. I also have lemon grass and a bay tree.

I live in a similar climate and was planning a heat tubes system with off-the-shelf greenhouse, with insulated walls/ceiling, and walls that roll up for summer.

What factors in your design contributed most to the heat? and were cost effective?

E.g.

Horizontal insulating panels in the ground does not seem that useful because:  

"the total heat reaching the surface of the Earth of (1.8+0.0000058) = 1.8000058 watts/cm^2, only 0.0000058/1.8 = 0.0003% is contributed by the Earth's internal heat. This, of course, will dominate everything else if the Sun were to magically vanish!" - Source: Nasa

I dont have compost material, and prefer low management.



Cost:

"Phase change materials" - like glycerin cost $500 for 55 gallon barrel, so the net effect on temperature needs to be justified, whether 1 drum of glycerin or 10.


Etc....  There were a lot of moving parts, several which were not real clear from a non-engineer/builder.  

If your system did not stay above freezing at night (got lost in really long thread), or if I want to have a more tropical solution, I am thinking to combine with heat tubes.

The biggest contribution to heat is definitely the sun.  The biggest loss is the glazing.  Leakage is minimal with my design but it's probably the next biggest loss.  I feel pretty good about the foundation insulation.  I don't follow your watts/cm2 comment though, could you elaborate?

I don't think the compost provided much help and it did generate gasses and odors at times that had me worry.  The moveable insulation seems to give me 10 degrees of help on cold winter nights but it's a pain to deal with in the manner I implemented it.  

I haven't done the glycerin but if I did I was going to try to find a biodiesel maker who might have it as a waste product.

I am trying to collect heat off the ceiling and blow it through a radiator to store heat for the night time.  Hopefully I'll have results this winter.

I passed on the earth tubes since I was aiming for more heat generation at night than I believe they can provide in my climate.  Since it's cloudy 80% of my November and December, earth tubes would only be drawing from the deep earth temperature.  Here that's in the low 40s.  It's hard to do much heating when your heater is putting out 40 degree air.

This winter I didn't bother with the insulation and on our coldest night (-29F) it got down to +9 in the greenhouse.

@pete, the foundation insulation essentially creates extra thermal mass similar to barrels of liquid, phase change materials, or thick solid walls above ground.  Without any thermal mass the temperatures swing wildly.  Take a look at some of Shannon Mutschelknaus' greenhouse design inspired by U. Minnesota's Deep Winter Greenhouse:

Intro to Passive Solar Greenhouses: Session 1 <https://www.youtube.com/watch?v=BI7Br7XcTs4&list=WL&index=30&t=2022s>;

Intro to Passive Solar Greenhouses: Session 2 <https://www.youtube.com/watch?v=MzuhkbzSqEA&list=WL&index=29&t=4743s>;

He did a little thermodynamics modeling and found how the heat transfer differed with and without wings, as well as insulation thicknesses.  His foundations are only 4' deep (I was actually expecting more), and his earth tubes are at 4' and 2'.  BTW, his place is in central South Dakota, and it gets COLD there...  Anyway, I hope you find his examples useful.

Thanks for sharing :)

Hi, Mike,
I'm sorry I didn't see this 3 years ago!
One thing we've done is to build a concentrating solar heater into the S glazing. The basic idea is, we bought 3" thin-wall PVC sewer pipe; sliced each piece in half lengthwise; sprayed the interior with "metal reflective" spray paint; then used little wires to attach 1/2" black poly tubing at the center of the back of each reflector. This geometry directs pretty much all the reflected sunlight onto the black tubing.  We screwed the reflectors, on 12" centers, to 2x2 braces attached to the structure. This geometry admits 75% of solar light/heat into the space, absorbing the remaining 25% in the water flowing in the tubing. We used the cheapest Grundfos circulating pump to circulate the water to (3) 55-gallon drums for heat storage. In May of the 1st year, after a week of thermal heating, the water in the drums warmed up to 95 degF, killing the goldfish in the barrels. (Later we fixed this with some electric logic that stops the pump when the drum temp reaches 80 degF.)

Our 1st greenhouse was a typical cheapie plastic-coated hoop house maybe 10' wide(?), that blew down in some sudden intense wind gusts this site (S. Oregon) gets in summertime. The GH we have now we framed with a ridge beam & posts, and 3/4" PVC diagonal pipe braces to resist both the wind loading from the West, and the snow loading on the crown -- which I'd seen crush a neighbor's hoop house. When the frame was finished, my friend and I both pushed on the end post as hard as we could (with no glazing yet), and deflected it only about 1/8". (I will soon be posting more details of this structure in a website called sustainability101.org) But I think I like your "Gothic arch" design better. Does your attached glazing counteract wind shear on your structure?

Hi Jerry, I don't think the glazing does too much but the metal roofing on the other half does a lot of work.  I also had diagonal metal strapping on the roof side during the construction process and it's still buried in there somewhere.

That's a neat way to capture and concentrate the heat into the greenhouse for storage.  I have the infrastructure partially arranged to collect hot air off the ceiling and transfer it to water tanks in the the mini greenhouse.  But concentrating it first makes a lot of sense...  Thanks for the idea!

The gothic arch is great it every way except for construction.  Detailing the corners was a real pain in the ass.  Especially since on my build the wall members were inside the walls on the E and W and on the interior of the N wall.  So getting vapor barriers and housewrap to go around the corners was a pain.  As was figuring out how those curves met the flat E/W walls.

Mike Haasl wrote:Hi Jerry, I don't think the glazing does too much but the metal roofing on the other half does a lot of work.  I also had diagonal metal strapping on the roof side during the construction process and it's still buried in there somewhere.

That's a neat way to capture and concentrate the heat into the greenhouse for storage.  I have the infrastructure partially arranged to collect hot air off the ceiling and transfer it to water tanks in the the mini greenhouse.  But concentrating it first makes a lot of sense...  Thanks for the idea!

The gothic arch is great it every way except for construction.  Detailing the corners was a real pain in the ass.  Especially since on my build the wall members were inside the walls on the E and W and on the interior of the N wall.  So getting vapor barriers and housewrap to go around the corners was a pain.  As was figuring out how those curves met the flat E/W walls.

======
Hi Mike et al.

I haven't read the entire thread but I suspect that Permies hasn't heard of/don't know about the Univ of Minnesota DWGs = Deep Winter Greenhouses. Which are now being used commerically to grow and sell produce in the deep winter months. Their heat source is a foundation filled with washed rock, piping system within where the heat of the day/sun is captured and delivered to the rock bed for night time delivery back to the GH to prevent freezing. Y'all really out to check it out.

Deep Winter Producers Association

https://www.facebook.com/groups/845092875544652/about

Mike Haasl wrote:Hi Jerry, I don't think the glazing does too much but the metal roofing on the other half does a lot of work.  I also had diagonal metal strapping on the roof side during the construction process and it's still buried in there somewhere.

That's a neat way to capture and concentrate the heat into the greenhouse for storage.  I have the infrastructure partially arranged to collect hot air off the ceiling and transfer it to water tanks in the the mini greenhouse.  But concentrating it first makes a lot of sense...  Thanks for the idea!

The gothic arch is great it every way except for construction.  Detailing the corners was a real pain in the ass.  Especially since on my build the wall members were inside the walls on the E and W and on the interior of the N wall.  So getting vapor barriers and housewrap to go around the corners was a pain.  As was figuring out how those curves met the flat E/W walls.

Glad to hear your greenhouse is still going. Haven't been on the site for awhile.

Mike, how are you doing this winter?  Any news on how different plants are doing for you?

Good reminder Ebo!  The greenhouse suffers for the lack of a fairy who will keep lovely plants growing in there as much as it deserves.  

This fall I enclosed the area where the compost bin was located to be a seasonal "mini-greenhouse".  I used twin wall polycarbonate and taped the joints with clear tape.  I'm going to remove the panels during the warm season and reinstall them each fall.  That way the citrus can be planted in the ground in there.  I have a little electric "milk house" heater in there to keep it above freezing.

In the main greenhouse this year I started all my seedlings (>1000), grew luffa sponges and the main bed had kale, carrots, lettuce, tomatoes and a few other things in it.  I've come to learn that insect pollination in the greenhouse is next to nil.  Ants did pollinate some flowers but very poorly.  Cut and come again lettuce worked well in the early spring.  Tomatoes fruit ok but do much better outside.  I suspect they just need a bit more light and wind (to shake their flowers and pollinate).  So veggies do better than fruits and insect pollinated fruit is close to useless unless I want to hand pollinate.  I will do that for the citrus though...

My overstory goal for the greenhouse is figs and pawpaws.  I planted the two surviving figs I got from Greg and they put out some growth this summer.  I think they'll overwinter more solidly in the ground and should do nicely next summer.  I got pawpaw seeds this fall and planted 4 of them in one spot.  I think they'll do just fine with the temps in the greenhouse and the slight shade.  So I'm hoping those will be the overstory in my zone 7-8 greenhouse.  Then I can fill in with more stuff.

Nice update!  Thank you.  I am not sure how people normally deal with pollinators in greenhouses, but I have seen one place where they had a bee hive in the back of a greenhouse, and they installed two entrances to the hive -- one inside and one outside which both can be blocked off.  That way you can get them to pollinate stuff inside as well on good days.  Do you keep bees?  I wonder if there is some way to also capture and bring in native pollinators like solitary bumble and mason bees, butterflies, and other such.  Also, I read some place where a guy did a caterpillar tunnel inside of his regular greenhouse where he grew ginger year round.  Your setup reminded me of that.  Best of luck on all your plans!

Hmm, ginger and turmeric sound like they should go in the mini greenhouse.......

I don't keep bees, they don't really like to live in my climate.  People who do have them round here and keep them in warmer sheds have them die anyway.  So if I had them in the GH they'd probably not make it either.

Mike Haasl wrote:

I don't keep bees, they don't really like to live in my climate.  People who do have them round here and keep them in warmer sheds have them die anyway.  So if I had them in the GH they'd probably not make it either.

That is strange, Mike, because bees are kept in all the Canadian provinces. I know of one guy who raises them [honey bees] who says he just wraps their hives with tarps and they survive, outside, in minus 40s and lower, at latitudes of 53 degrees and higher. He told me he has even found some who leave the hive in the winter frozen near his house.

We had an old tobacco greenhouse here in SC a few years back where we raised early tomatoes.  Used an old electric toothbrush to vibrate the flowers to stimulate the pollination.  Worked out really well.  

Was that self pollinating, or did you run the toothbrush across different flowers on different plants?  That is an interesting idea. Also, did you just yous the bristles strait up, or tape a q-tip to the end?  I am actually interested in this.

@Mike, I know of a lot of people who do bees way up north.  My guess is that if they are having those types of issues it is colony collapse or some persistant disease.  Call the extension agent at your nearest university and talk to them.  They will know the details.

I just know from talking to many people in the local homesteading club that bees are rarely successful here.  There's a major honey guy in town and the only way he does it is by trucking his hives to California for the winter.  Maybe we're a bit too humid and cold, maybe the bees wake up too soon, no idea.  But I haven't heard of anyone around here that's had better than 30% success getting hives to make it through the winter.  

Maybe there are other bees (like Mason Bees, or others that can be found here https://hort.extension.wisc.edu/files/2016/08/WI-BEE-IDENTIFICATION-GUIDE.pdf ) which you can encourage there.  

Ebo David wrote:Was that self pollinating, or did you run the toothbrush across different flowers on different plants?  That is an interesting idea. Also, did you just yous the bristles strait up, or tape a q-tip to the end?  I am actually interested in this.

Tomatoes self pollinate and can do so from the individual flower.  All that's required is to use the toothbrush to vibrate the stem or flower, thus causing the pollen to drop onto the stamen.  Tomato flowers face downward which allows natural events like wind or bees to vibrate them and cause the pollen to drop.  It's actually a quick and easy process of going from one plant to another, just touching individual blooms with the vibrating head of the brush.  No pollen transfer from one blossom to another with the brush is required.

Dave

Thanks Dave!  I may end up experimenting with this and working with someone to do a video to post to the Master Gardner's lists.  I can see this as being a great way to pollinate tomatoes and other self pollinating plants inside a greenhouse!  This is SO cool ;-)

Ebo David wrote:Thanks Dave!  I may end up experimenting with this and working with someone to do a video to post to the Master Gardner's lists.  I can see this as being a great way to pollinate tomatoes and other self pollinating plants inside a greenhouse!  This is SO cool ;-)

Try YouTube.com... there are a number of videos there showing how to use an electric toothbrush to stimulate the pollination of tomatoes.  Good luck, and have fun!

Dave

<face-palm>  Yea, I guess I should have did a search before making that post.  That said, I can definately see presenting that to one of the next Master Gardner's meetings.  Thanks!

David A. Smith wrote:

Ebo David wrote:Was that self pollinating, or did you run the toothbrush across different flowers on different plants?  That is an interesting idea. Also, did you just yous the bristles strait up, or tape a q-tip to the end?  I am actually interested in this.

Tomatoes self pollinate and can do so from the individual flower.  All that's required is to use the toothbrush to vibrate the stem or flower, thus causing the pollen to drop onto the stamen.  Tomato flowers face downward which allows natural events like wind or bees to vibrate them and cause the pollen to drop.  It's actually a quick and easy process of going from one plant to another, just touching individual blooms with the vibrating head of the brush.  No pollen transfer from one blossom to another with the brush is required.

Dave

Would using a fan work as well?  I know I personally would do the toothbrush thing about once before I "forgot" about it and never did it again.

Trace Oswald wrote:

David A. Smith wrote:

Ebo David wrote:Was that self pollinating, or did you run the toothbrush across different flowers on different plants?  That is an interesting idea. Also, did you just yous the bristles strait up, or tape a q-tip to the end?  I am actually interested in this.

Tomatoes self pollinate and can do so from the individual flower.  All that's required is to use the toothbrush to vibrate the stem or flower, thus causing the pollen to drop onto the stamen.  Tomato flowers face downward which allows natural events like wind or bees to vibrate them and cause the pollen to drop.  It's actually a quick and easy process of going from one plant to another, just touching individual blooms with the vibrating head of the brush.  No pollen transfer from one blossom to another with the brush is required.

Dave

Would using a fan work as well?  I know I personally would do the toothbrush thing about once before I "forgot" about it and never did it again.

I'd recommend you watch some of the YouTube videos using electric/battery powered toothbrushes.  I know that there are at least two, and probably many more, demonstrating this method.

Dave

Nice to see innovation like this. I will try to incorporate some of this into my new project in the French countryside. I already have cellular concrete slabs salvaged from the renovations to make a solid insulated north wall.

I finally got some pics inside the mini-greenhouse.  It's not that "mini" but it is relative to the overall building.  I made it so the sides are curved and almost past vertical for the bottom 4 feet.  That way the citrus can be planted outside the footprint of the roof above so they'll get more sun in the summer.  I'll have to keep pruning them back as they lean out towards the sun but I'd have that regardless of the glazing shape.

The East wall is a flat plane since there's a ladder there to get up onto the yoga platform.  The SE and S sides are curved.  That made for some fun joints.  For reference, that's a 6' step ladder in the last picture.  My lime, Australian finger lime and lemon have several fruits on them right now and I'm really hoping they take off when they get out of their pots.

Question for you Mike,

You've had time to tweak your design and put it to the test over multiple seasons as well as seeing the Wofati greenhouse and the initial data. If you had to go and do it all over again, would you build something similar to you have already done (Passive Solar Greenhouse) or would you try something more similar to a wofati (Annualized thermal inertia)?

I know your greenhouse still uses thermal mass, but I'm curious to see if the wofati greenhouse peaked your interest.

At first blush, I'd say they're for different purposes...  Mine was targeting a tropical 16' tall food forest, the wofati greenhouse is aiming to keep a greywater system from freezing.

I'd say that if I lived a bit further south (where it only occasionally gets below 0F) my greenhouse could be happily filled with citrus and tropicals without any added heat.  Or if it was in a sunnier location with some more thermal mass, it could handle a bit colder.