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Passive Solar Greenhouse with Integrated Aquaponics System  RSS feed

 
Jacob Freepons
Posts: 33
Location: Costa Rica
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Hi Zach, I wanted say that I really appreciate your sharing of info on Sepp's design philosophies and your own in-depth knowledge. Thank you.

I am working on a conceptual design for a passive solar greenhouse with an integrated aquaponics system for a potential client and I would be most grateful for any feedback on my designs that you could share here.




Ideally I would like to have the north wall earth-bermed. For the east & west walls we are contemplating using strawbale for high insulation figures.
One of my specific questions would be on the ratio of glazing on these east and west faces. My feeling is that this will be largely site dependent.
Do you have any kind of rule of thumb that you would use for this?


Your website looks great and I would like to learn more about your designs in the future.
Pura Vida

 
Zach Weiss
pollinator
Posts: 296
Location: Montana
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Great looking plans! I can't read all of the text (gets too fuzzy when I zoom in) but I'm happy to give you my feedback on what I can read. It looks like you've though about passive ventilation with the clear story design. You've got the solstice sun angles on there and it really looks like you've given it some good thought. I really like the relatively low glazing angle so that you will get plenty of summer sun. What type of fish are you planning to grow? Will you be heating the water? Have you looked at a compost heat recovery system for this? Greenhouse design is a pretty climate dependent thing so it is hard to give too much feedback without knowing more details about the site location.

I can certainly attest that the farther you bury this thing in the ground the greater the climate buffer in the resulting greenhouse. As for glazing vs insulation on the east and west walls this is really a matter of what the client desires to grow. If growing fruit and other crops where the more sun the higher the quality then glazing on the east and west walls can really pay off despite the additional heat loss. If keeping the greenhouse warm during the winter is your main goal then insulation may be a better approach. It all depends on what and when you are seeking to grow. Either way the glazed roof of the structure will be your primary heat loss. If winter temperatures are a big concern I think that an insulation blind (that comes down during the night) is well worth the added expense.
 
Jacob Freepons
Posts: 33
Location: Costa Rica
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Zach, the site is at roughly 3200' and 35 degrees N., in the high desert of California, north of LA.
Because of the altitude and other climate effects they get alot of sun year-round and have a large swing in diurnal temps. both in the summer and the winter. My gut feeling is that ventilation of high day time temps is going to be the biggest challenge. The plan is to moderate day time heating by storing it in the AP system, the thermal mass along the north wall and good venting. Ideally I would like to sink the whole thing a feet few blow grade as well as berming the north wall.
The idea of using earth tubes in the CRMPI style has also been a possible design consideration. I like the concept but the calculations for a greenhouse of this size requires big fans, lots of tubing and power... I am not totally sold on it. Do you have any experience with their technique? Or other thoughts on earth coupling, either for cold air intake or thermal storage?

Thanks for the info on the glazing, crop plans have not yet been determined but the designed AP system is weighted towards producing leafy greens in floating rafts. I am thinking that I would like to use glazing on the upper half of the walls to the south and let the earth berming wrap around in the north. Insulating all along the bottom half and using onsite sun angles to determine where to start with the glazing going up.
Along that line, have you used Solexx? What are some of your preferred materials for glazing? I would like to use old sliders but the remoteness of the site will make this difficult...
I think that we are going to need shade cloth in the summer regardless of other strategies and maybe designing a roll up system that can be switched between summer shade and winter insulation would be pretty cool...

I like to go with native fishes for my projects as much as possible. Sturgeon will be the main species in this system.
Water is heated solely through solar gain. The design also includes black 55 gallon barrles stacked 2 high along the north wall. The shallow (12") troughs pick up heat really well and when circulated to a sunken tank it becomes a very effective thermal mass. I have been thinking of backup systems for heating, I have used compost heating (Jean Pain method) for domestic water heating before and had good results so I think that stacking these functions would be a great fit. I also have had good luck using flat coiled black poly pipe laid out on the earth...
I am really curious about the balance of thermal mass. At what point is it too much? The mass will moderate temperature swings but when does it begin to hold too much heat, losing the ability to effectively cool off in the nighttime? Do you have a formula or work through for this?

Thanks for your responses and time on this.
J
 
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