I'm in the planning stages of designing an AP greenhouse. I live in zone 6b. My initial thoughts were to build a passive solar greenhouse, in an effort to have a system that is more sustainable. I'm hoping to use solar panels to generate the electricity needed for the pumps etc.. But for heat I'd prefer to heat with the sun. This will be an all year greenhouse, I hope. Approx. size 15'x30' (15' tall). The greenhouse will have a clear southern exposure year round. Possibly a strawbale northern wall(r-40) value.
Is there anyone out there that has had any success with passive solar greenhouses for AP? Is this even possible?
What are common problems with those that have a greenhouse for an AP system?
Any thoughts, suggestion, ideas welcome.
Thanks in advance,
Well you can use this - http://www.solaroof.org/
You could technically pump the heat from the day from multiple sources into an undeground pipe system that would heat the ground and then extract the ground heat at night.
Lots of options just gotta pick one.
I think you're asking the right questions - I'm curious how far your planning has come.
Look at glazing systems that balance light transmission with higher U-value - first thought is a double-celled (three layer) polycarbonate sheet. Keep things airtight when you are not ventilating. R40 straw bale wall could work very well, though it doesn't lend much thermal mass; also consider concrete masonry units with insulation to the exterior (and maybe sand or grout in cores).
AP water tanks are natural heat sinks. Perhaps someone has figured out a gizmo for aerating fish tanks with the heated air at the top of the greenhouse to increase water thermal storage? I've done concrete-block-under-floor air circulation as a seat-of-the-pants thermal storage before - I don't think this is where you want your heat to go, though. You want to keep the water and the growing media warm, not the floor.
Speaking of gizmos, has anyone looked at combining rebuilt Prius batteries with PVs for a low-volt household system?
I'm in 6b.
I like having the north wall as an insulated wall.
Storing or creating energy to make heat at night is a big and I mean big science lesson.
Look at how many btu's per hr you will need maximum then see how much wattage is needed to create that qty.
I'd look at a small woodfired water heater if possible.
Also a design that allows an extra layer of plastic inside for the few months of the coldest temps (each layer of material is the equivalent of going about 500miles south)
I'm adding glass on the south wall next summer.
This is 48x20, trusses every 3' , ceiling is 7' south side 9' against the bldg , max ceiling height is 11' against the bldg.
The roof is sheet acrylic designed for greenhouses.
The north wall has a 12" insulation capacity and will be filled with styrofoam . The room will be another lumber dry kiln do the insulation will dual purpose. And the kiln heater will be set up to send heat to the gh if needed.
Trusses were $50ea, lathed on top with treated 2x4, acrylic for the roof was $2100. and 7ea. 6x6 posts.
On the N side of the gh I have 4ea 4'cube fiberglass containers that will be buried in the ground. These will have tall plants in them.
The woodfired heater in the pic heats 1600sf wood shop , lumber dry kiln holds 3000sf of lumber, 1000sf apartment, 700sf woodwork showroom, 300sf dog grooming shop, 3000sf house (she's 1890) (got the newspaper article from when the house was built,, cost was $900 materials $700labor).
It's the biggest unit Taylor makes and when its real cold the unit can't keep up so we use supplemental heat in the house and the kiln has to be off.
I'm setting up a gasifier now so soon the woodfired heater will be out of business.
I built a passive solar greenhouse based on a Chinese design. I've almost gone through the whole winter with it and I can say that they work. I've seen up to 60 degree difference inside to the outside when the sun is out. Currently I'm having to cool it down since it gets way too hot inside. I don't have pictures uploaded. I'll try to get some shortly.
Thank you for sharing your photo's. The greenhouse looks great!!! Do you have plans yet on how to cool it down? My biggest hurdle is going to be cooling it down in the summer. I live in southern middle TN. Summers great pretty hot. Did you use a particular company with a kit to build the greenhouse? Yours looks about the size I need. I just have to figure out how to cool it. I've looked into subterranean cooling. My plate is so very full right now the greenhouse has been put on the back burner and the cost is prohibitive too. Your photo has inspired me though! Thanks so very much.
Tarz said:I built a passive solar greenhouse based on a Chinese design. I've almost gone through the whole winter with it and I can say that they work. I've seen up to 60 degree difference inside to the outside when the sun is out. Currently I'm having to cool it down since it gets way too hot inside. I don't have pictures uploaded. I'll try to get some shortly.