I'm looking to build a large scale(30x90) passive solargreenhouse in zone 5b, capable of being considered a forest garden greenhouse and growing small tropical trees, I'd like to jump 2 or 3 zones to zone 7 or 8. I've read the forest garden greenhouse and it seems that most of the greenhouses that are of large scale end up going with expensive concrete foundations with huge metal rafters in order to have a really large span, the cost of these heavy duty structures is too much.
I'm going to pose some questions here and answer them myself. Please feel free to jump in and provide your own answers or thoughts.
Why do we need so much concrete to build a passive solargreenhouse? I think we could do it with almost 0 concrete or at least just concrete posts in a few spots instead of a full foundation wall.
Can we use a much cheaper structure, such as a hoop house? I think we can use a cheaper structure like a large hoop house that is built to withstand snow load(https://www.rimolgreenhouses.com/greenhouse-series/noreaster to example hoophouse). On the north wall and roof, forgo glazing and insulate with spray foam sandwiched between two billboard tarps, one fixed to the interior of the north wall and one as a cap over the spray foam on the exterior.
I would also add frost insulation in the ground around the perimeter of the greenhouse, have insulated east and west end walls as well as a climate battery (GAHT,SCHS).
Passive grreen houes
- catch and hold the suns heat
- have mass masonry or concrete to hold and release stored heat
WIDE CLEAR SPANS
- enable movement anywhere in a commercial greenhouse with no restrictions as to the type of equipment
Frost insulation is admirable but you need heat storage banks also.
Try you ideas with the billboard tarps and let us know how it works.
The Rimolgreenhouses look great and serve a purpose well.
- They are not passive
- they use gas heaters
John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan