Mike's passive solar greenhouse design/build

Very nice.  Thank you for sharing!

Looks fabulous!  Really nice job!

Oh Mike, that is AWESOME!!! I love it!!
I LOVE seeing your dream become reality for you!!

Beautiful work! :D
Pearl

Thanks Pearl!  Progress has been a bit slow due to catching Lyme's disease a couple weeks ago.  But the antibiotics have been working and I'm feeling good again so I'm gonna get back at it.  More pics soon...

I'm glad you are feeling better Mike. I caught Lyme's disease while hiking the Appalachian trail in 2014. It took me 2 days to hike an easy 12 miles to get to the road and hitchhike to a hospital. I felt almost 100 percent after 2 days on antibiotics and started hiking again.

It was on this hike that I realized that I wanted to live in harmony with nature. I discovered permaculture and permies shortly after my hike ended. I have not posted much yet, but I have been learning a great deal. I hope to start using all I have learned on my new land in Michigan when I move up in the spring.

I will enjoy seeing the progress on this greenhouse

Sorry for the delay...  Since the last pictures I put in the frames for the upper vents in the North wall.  Then I built the vents and slid one up into place.  Not fun.  But it fit and hinges open and all that.  The vent at this point was a 4' by 8' frame of 2x4's with an infill of two sheets of 2" poly iso insulation.  Menards had a special order that didn't work out so they sold me the sheets for $18 each

Once I knew it fit, I put metal roofing on the other 4 vents.  Unsurprisingly that made them heavier.  Unfortunately I still needed to put metal on the one vent I already installed 18' off the ground.  A few hours later that was taken care of.  And I didn't fall to my death.

Tomorrow it's supposed to be nice out so I hope to winch the remaining 4 vents into place.  Today I also started framing one of the walls.

I also got a load of pine boards back from the kiln and we planed one side and cut them to length for the North wall.  The missus will stain them white and then we'll put them up and cover them with visqueen.

The first photo is of the one vent that is installed and propped open.  The second is from another angle with two of the vents sitting on the ground.

This is coming out really nicely, congrats on a well thought out plan and seeing it through. It's really cute too, smiles!
Brian

Thanks Brian!  I hope it's well thought out.  I've probably spent a few thousand hours thinking about different details.  But I'm sure I'm missing many more.  Hopefully it works the way I want in the end.  Worst case I'll still be able to grow lettuce.

Since the last post we installed the remaining 4 vents.  The process was to screw them onto a temporary guide that would ride up my big extension ladder.  I made a block and tackle and a clamp-on support at the top for it.  I could then pull them up myself into position.  Then we'd carefully prop the vent open and get the hinges in the right place and screw them onto the frame.  

My next step is to frame out the E and W walls to be 7" thick and optimal for the 4x8 sheet siding to attach.  Then I'll scab or fur out the edges of those walls to match the final shape of the metal roof on the North.  Then I can put on the pine, visqueen, insulation, curved purlins, housewrap and metal roofing.

Hopefully winter holds off for another 5 months or so.....

We have a couple varieties of heirloom tomatoes that we have not been able to kill in our earth-sheltered greenhouse in three years. You'll be so happy when your greenhouse keeps plants going all season too! It really is a game changer.  
Here in the mountains of NM 7100 feet, after some very hot weather this Summer we got a couple little rain storms and it felt cool for the first time yesterday morning. First thing that coolness does to me is make me go over in my mind every single crack and crevice around the house that needs fixin' before Winter. Homesteader's deadline.
Brian    

Cool, so the same tomatoes are living for 3 years?  That would be awesome!  I've heard bell peppers are actually perennial plants in warmer climates.  Here we plant the poor things outside and hope to get 4 peppers off of them before the fall frost kills them.  Having a pepper bush inside that gives peppers year round would be a game changer.

A few tomato vines are two years, I keep changing them out, actually not by design at first;  After the first season a botched fiberglass job made one of four media beds to leak. I had to pull the plants from that bed and replant after I relined the bed with pond liner. I do have one four foot tall bell pepper plant in dirt  that has been producing since this time last year.  No heat in the greenhouse either. The design is from Mike Ohler's earth-sheltered greenhouse book.  
Brian

@Brian, can you post some pictures of the beds you are referring to?  Are the ones you lined with pond liner for hydroponics, or are these fiberglass beds just plant beds, and if so why are they closed off?  Is there no drainage?

 EBo --

Thanks for asking Ebo.
The media beds are in a flood and drain aquaponics system Brian's earth-sheltered aquaponics greenhouse
The fish pond in our greenhouse is 2600 gallons. We basically feed upto 100 Brook trout at a time which in turn feeds bacteria, which converts ammonia to nitrite and then nitrate which feed the plants, returning the water to the pond to start the nitrogen cycle again.  

Mike :  This is absolutely awesome !!!  I'm so glad I asked you about photos !

My pleasure!  I'm delinquent again about posting photos.  The missus stained all the pine for the north wall and it's now all been installed.  Luckily my big extension ladder, when separated into its two pieces, make the perfect size ladders to work on the N side.  I have the East side framed out and I started on the West today.  

I have a bunch of donated wood and fiberglass insulation that I'm trying to use on this build.  It's great for the budget but makes the construction a bit interesting.  The free 2x4's are actually 1.75 by 4 (give or take 1/4", they all vary).  I was counting on a 7" thick wall (double 2x4s) so now I have to get creative with 2x2s to hit my target thickness.  The inner part of the stud wall is a normal 16" on center wall and the outside part of the wall is optimized for easy installation of 4x8 fiber cement siding sheets in the month to come.  

After discussing with an architect (brother in law) I realize I need to separate the pine from the visqueen on the North roof/wall.  Otherwise condensation against the visqueen would just sit trapped between the plastic and the wood and rot it out.  So I got some Aquavent material on order to provide the room for it to breathe.  This is the same stuff they suggest putting under wood siding and shingles.  Hopefully it arrives before the next rain is forecast.

I also tried to put in a sand point well but it's kicking my ass at the moment.  That's on hold until I get the building weathered in.

Wow, this thing looks like a piece of art.  

I also tried to put in a sand point well but it's kicking my ass at the moment.  That's on hold until I get the building weathered in.

 
Okay, I'll bite: What is a Sand Point?
That is so smart to recognize that the wood to plastic interface will weep.  
Brian

Thanks Scott!

Hi Brian, a sand point is a "driven" shallow well.  You get a "point" from the hardware store which is either 1.25" or 2" in diameter with a mesh screen to allow water into it, threads at the top and a spear point at the bottom.  You assemble it with 5' sections of pipe and special couplers and pound it into the ground.  Once you hit water (ideally before you get to 25' deep) you hook up a shallow well pump to it and voila.  If it's rocky they don't pound in so nicely.  

I thought I needed to do the well before I got the pine boards on the North wall since I planned on augering the well instead (needed 15+ feet of headroom).  Now that augering failed and I'm using the sand point, headroom isn't an issue and I can return to construction of the building.

cool thanks Mike. I hadn't heard of that before.

Ok, I have more pictures.  Man it's hot out.  I started calling this "The year of three Augusts" back in June.  I think I under-predicted.  85F and humid today.  Sheesh.

The Aquavent material arrived so I got that installed today.  Now the outside is black instead of white so it hides from view better.  The East wall is framed up except for the corner where it meets the roof edges.  And I just got the inside half of the West wall framed up.  

This week I picked up 3 patio doors from the Habitat Restore.  They were 8' tall doors and had been sitting around for a while so I got a good deal on them.  They will be the entry vestibule on the East side.  One will be the exterior door (reworked to open outwards).  The vestibule will be inside the insulated envelope of the greenhouse.  It's the size of a pallet (48" by 40") since an IBC tote will be acting as a water tower above the vestibule.  The other door of the vestibule is another of these patio doors.  The south side of the vestibule will be the third door (stationary).  I may go back and pick up a fourth one to do the North side as well.

Once the West wall is framed I can detail out the corners where the walls meet the roof (and glazing).  Then I can plan a roofing party.  

Photos:
#1   Sliding one of the roof vents up a sled that fits to my extension ladder.  Pulley system attached to a 2x4 at the ridge.  Worked pretty well and kept us safe.
#2   Staining the pine boards and installing them.  Gaps are deliberate to give some airflow between the boards.  Gaps are also hard to avoid since I didn't joint the boards.
#3   Boards halfway installed up the North side.
#4   Boards done, X brace strapping installed, wooden brace to the ground removed and wall ready to be tilted up into place.
#5   Aquavent installed.  Had about 40 square feet to spare
#6   View of the inside.  Chop saw for scale.

I read earlier when you first started this article questions about the pros and cons of using a blower between two layers of Poly. I recently attended a program with a local retired orthopedic surgeon turned green house promoter. In his poly tunnel he uses a blower. He's also elected official in NH so he's pretty easy to reach if you want some real-life experience with someone.   Jerry Knirk is his name and his web site is: http://www.jerryknirk.com/

Thanks Josephine!  I think I've thought through many of the pros and cons of the blowers and how they'd apply to my greenhouse.  I think the blowers are awesome for hoops with a single hoop structure and two layers of poly.  That way with the blower you can separate the layers.

I'm planning on using cedar strips 1.5" tall on my ribs to separate the two layers.  I hope that's enough separation (on 4' centers) so that the layers will not touch.  I figure if they both sag a bit they'll sag in the same direction and stay spaced apart.

That works well (I hope) with my moveable insulation.  I'll type up another post about how that works.  I figure I can always add a blower if I need to later as long as I leave gaps in the cedar spacers to let air flow across the glazing wall.  I would suck in outside air for the blower so that it doesn't cause condensation issues.  I assume that if there aren't big leaks, the fan wouldn't actually move much air into the gap so it wouldn't be cooling off the greenhouse.  One notion I had was to make a blower that ran directly off a windmill.  That way when it's windy, it's inflated.

Here's how the moveable insulation will hopefully work.  Part of the premise is that there isn't a good place to put moveable insulation.

If you put it inside the glazing surface it has to be very snug on all sides so that you don't get convective air currents pulling warm air behind the insulation, cooling them off and then returning them to the greenhouse.  They also will often condense and the side to the glazing could freeze, possibly onto the glazing.  Unfurling and retracting the insulation is tricky around plants, lights and other obstructions.

If you put it outside the greenhouse you have a whole different host of problems.  The insulation has to be able to get wetter.  It needs to be held down well enough for high winds.  What do you do if there's a foot of snow on it?  If water gets behind it and freezes, how do you get it off.  And how do you retract and unfurl it, especially if your greenhouse is 18' tall.

My brainstorm was to put the insulation in neither spot.  Instead I'll put it between the two layers of poly.  I think that eliminates most of the downsides to either location.  The new challenges are unfurling and retracting and how to get it between the layers without letting greenhouse air leak in between the layers.

So here's my plan:
I'm going to use a double bubble wrap insulation that has reflective mylar on one side.  Reflectix is one brand name, I got some from Menards that is for pole barn insulation.  It comes in a 4' by 100' roll.  At the peak of the greenhouse I'll have 47" wide strips of this insulation wrapped around a pipe the runs the length of the greenhouse.  The rolls will fit within the thickness of the trusses.  The insulation will feed down in between the two poly layers of the glazing.  The inner glazing will stop a foot short of the peak of the roof, the outer glazing will go to the peak.  I'll box around the insulation so that it is effectively part of the space between the layers and sealed from the greenhouse interior.  I'll rotate the pipe to unfurl/retract from one end with a chain and sprocket.

One concern is that the insulation may not want to unfurl down the glazing under its own weight.  If that's a problem I'll either put a weight at the bottom of the insulation or use elastic ropes to help pull it for the first 5-10 feet.

Another concern is that the insulation may not travel down the spaces smoothly.  The trusses aren't perfect matches to one another (radius wise) so the insulation may want to veer over to one side.  I think I can just cut the insulation narrower to allow for that as needed.  Gaps on the sides of the insulation won't allow convective currents since it is separated from the greenhouse interior.

So that's the plan.  Anyone see any massive flaws or opportunities with it?

Where did you source the tote? I've been told to check Craig's List; however, is there any place (or type of place) people recommend for something food grade?

I've gotten them from Craigslist.  I wait to find ones that say "food grade".  The last batch I got from an organic farmer that is trying to give them away.

Very nice. No time to read it all right now but will be back soon. Noticed a comment about perennial peppers though. Try chili petins. Hot little beasties with a unigue flavor that seem to live forever in the right climate. One pepper per tomato makes a very tasty salsa.  

A lot of what's discussed in the thread goes way over my head, but I'm interested to see how this goes. One of my permie dreams is to build a solar greenhouse way down here in zone 4b. :)

Well, if it works up here, it should work for you too Molly.  What I think I see out there in the world of permie oriented greenhouses are:

Traditional passive solar

Subterranean heat storage along with passive solar

Walipini

These are great, especially in areas that have sunny winters.  In cloudy cold areas, they'll work to a point but probably not stay above freezing at night.  That's where I hope this design shines.  It should collect enough heat from the sun 9 months of the year.  With the moveable insulation (assuming I get it working), it can hold that heat and probably keep it from freezing 11.5 months of the year.  With the compost it should be awesome.  

If this works, hopefully it's a model for the upper midwest and colder portions of New England (and other worldly places of similar coldness and cloudiness).

Time for more pictures.  There has been a lot of fiddly work on the corner where the curvy North roof meets the East and West walls.  But I got that figured out and then put visqueen on the North side (vapor barrier).  I hadn't planned on any support between the pine and the roofing purlins but a friend suggested it.  So I cut some curved pieces of 2x8 down to the correct width and screwed them on for every other purlin.  Then I insulated it yesterday and put the purlins and housewrap on today.  Depending on the weather, I'll start the metal roofing tomorrow.  

Technical detail:  This housewrap is a "drainage" style so I'm counting on that to keep the underside of the metal roofing relatively dry.  I was going to put in strips of cedar between the purlins, on top of the housewrap to ensure any water that gets in can drain down and out.  But since this is a "drainage" housewrap I think I can skip the strips.  If I'm off base on that assumption, please comment as soon as possible :)

Wow Mike, I had lost track of this, that ROCKS sir!!! What a lovely and well designed project!! it's REALLY coming out well!
Awesome work, lovely design, you are amazing!

Thanks Pearl!  It's consumed my life lately.  Need to get it done before winter...  It was drizzly rain and cold and windy much of the last week but I still made some progress.  I got the roofing installed last weekend.  Since then I've worked on the South wall/roof edges.  I have found that there are a dozen little steps before I can do anything visibly neat.  To get the PVC trim boards on the E and W edges of the S face, I had to first block off the back of the curved truss holes so they look pretty later.  Then I have to install a piece of visqueen (vapor barrier) between the wall I already attached to the curved truss and the curved truss.  Then I make sure the wall tops are level with the curved truss wherever they end.  Then I staple a strip of housewrap to top of the curved truss and over the wall studs.  Then I can finally install the PVC trim.  The inner layer of poly will attach to that trim and then the wiggle wire will go over that.

Thanks to typing this out I just remembered that poly reacts with PVC.  Crap.  I'll have to verify if this PVC trim board is as bad on poly as PVC pipe....

Long story short, I got that done and then installed the moveable insulation pipe and bearings.  Then I put in the 2x8s that box in the insulation and the 2x6 cedar at the bottom of the South wall to hold the lower vents.  Meanwhile the missus has been digging around the foundation and installing the skirt insulation styrofoam.  I wish there was a more eco material for below grade insulation but I couldn't find one.

First photo:  Roof done (Finally)
Second:  Swedish skirt insulation
Third:  Cedar vent support board installed
Fourth:  Moveable insulation pipe and partially built box

Mike, that is a really beautiful build, one of the best I've seen.  Considering the height at the center, have you considered a couple of ceiling fans?  You could run them with a small solar panel.  In addition to moving the heat from the ceiling down to the soil and the plants, I've read that some amount of "wind" makes plants sturdier.

Thanks Trace, yes ceiling fans are in the plan.  I'm also thinking about doing a low grade air to ground heat exchanger.  Suck air off the peak on sunny winter days (so the vents don't open) and blow it through 4" drain tile pipes that are buried 6-12" deep in rows across the greenhouse.  Have them exhaust on the other side of the greenhouse (inside) at a lower temp and hopefully having condensed some water out for a phase change energy storage into the soil for heat that will help the plants over the nighttime.

Old man winter is coming in fast.  We got 2" of snow last week and have had nights below freezing and highs in the 40.  But a friend came by to help and that sped things up.  Since the last update I got housewrap on the E and W walls.  The missus got the insulation around the foundation done.  I got cement board siding installed to cover the styrofoam on all four sides.  That included insulating the South block wall which had been bare up to this point.  With my helper we put cement board siding on the West side.  I didn't quite realize how heavy that stuff is.  Putting the first run up with the bottom at 3' off the ground isn't too bad.  Forget about putting the next one above it at 11'.  We ended up cutting them in half to make them lighter.  Scribing them to fit was also a pain in the butt.  But it worked out ok.  For the East side I'm going to change over to fiber cement siding boards (8" wide).  They should be a bit lighter to install by myself.

The ground can freeze now, we don't have to do any more digging

Tomorrow the forecast is for 4mph winds so we're going to try to put up the inner layer of glazing.  That should be nerve wracking and hopefully fun once its over.  Then I have to install the spacers for the second layer (not sure how that will go) and put on the second layer of poly.  It's supposed to rain Thursday so I'd love to get the first layer on before that.

First pic is of the south knee wall with 4" of poly iso insulation, cement board and some fascia covering it.  Looks pretty spiffy if I dare say so myself.

Second pic is from the NW showing the newly covered West wall and finished North side.

And we put in a door and window on the West side...

We got the first layer of poly on!!!  We finally had a wind free day, enough preparation and the gumption to put it up.  It went well after I got it up on the peak and started lining it up.  It's stretched pretty taut, hopefully not too tight.  I temporarily connected it at the top to the wiggle wire that the outer poly layer will eventually connect to.

When the sun peeks out it really heats up fast in there

I also got the vents installed at the bottom of the south wall.  They're 6 patio doors from the Habitat Restore that didn't have frames and were an odd size = cheap.  I still need to detail them out a bit but they'll keep it mostly dry if it rains.  

I forgot we still needed to do more digging before the ground freezes.  Friends turned us on to a pile of black topsoil a church was trying to get rid of.  I hauled it home this summer and now we need to get it into the greenhouse.  So I built a planting bed along the south side from some cedar slab wood we had laying around.  The missus is hauling dirt to fill it.  In the middle of that bed is a 4" drain tile that will take the compost aeration air and heat the bed with it.  When the compost needs aeration, a radon mitigation fan will kick on to draw air off the top of the compost chamber and blow it over to and then down the length of the bed.  It will heat the soil and also hopefully condense water out of the air stream.  I think that counts as a phase change which will both add more heat to the soil and keep from increasing the humidity of the greenhouse.  At the end of the bed the air returns to the greenhouse.  Unless it stinks in which case I'll have to route it outside.  Air is let into the compost chamber under the pile with another piece of perforated drain tile that we haven't started work on yet.

Next priority is to get the spacers made and installed on the trusses to give a 1.5" space between the poly layers.  Once that's done we just need another wind-free day and we can get that second layer on.  

I also need to put in a chunk of the moveable insulation and see how it works.  If it needs help unfurling, I'll have to address that also before putting the second poly layer on.

First pic is of the poly on there with Doo the rooster checking it out
Second pic is of the vent doors in place with Salt the hen checking it out
Third is of the inside with our mess
Last is the planting bed with the aeration heat pipe and some soil added

It looks great, Mike!