Greenhouse
- http://www.themodernhomestead.us/article/Greenhouse+Basics.html
- http://www.youtube.com/watch?v=KZiqUZGjGc0
Versions
1.0
The goal here is simple. Gain experience, get something functional. Very straight construction. 5.5' tall walls, 30° slope roof that reach a height of about 8' in the center.
Summary
- Building construction
- Garden wall
- Garden bed
- Automate cooling (underground pipe)
- Aquaponics
I think a goal of running on aquaponics for a full year is a good milestone to upgrade to v2.
Layout
It will be 7ftx15ft. Internally, there will be a vertical garden wall on the north side, 3 ft of open walk space in the center with hanging pots and 2ft of raised gardens on the south side.
Construction
Pole construction, treated lumber in concrete anchors. It takes 5 8' 2x4s to construct one section of the frame. At $5.25 per, that's $26.25 each. If these are spaced 3' apart, I need 6 of them for $157, plus there will be 7 supports that run the length, for an additional 21ft of 2x5 for another $70. The sides and roof have a perimeter length of 21', by the 15' that's 315sqft. At $0.11 per sqft of covering, it's $35, but I'll double glaze for $70. So far, that's $300. Call it $400 for the nails and concrete.
I will do two rows of cinder blocks at the base to add some rigidity and anchor the covering.
Design and Equipment
A core arduino or rasPi will log data. If a network connection if feasible I'll use that otherwise, I'll just log it.
Garden Wall
This is the first thing to go in. A vertical garden wall on the north side of the building.
Grow Bed
This is the second piece. Hydroponic grow beds on the south side. Flood and drain with bell siphons.
Temperature
Incorporate vents along the top of the roof. After it's up and running, add an air inlet from an underground pipe. When the temperature is too high, automatically open the vents and turn on a fan to pump air through the pipe.
A later development will be to add a solar thermal panel. This will be connected (via heat exchange) with the hydroponics system. When it is able to keep the hydroponics system at a reasonable temperature year round, I can upgrade to aquaponics.
I'll want one main temperature sensor, one external and one in the air pipe.
Water
Rain water will be collected and filtered. When the primary cache is too high, just overflow outside. When the hydroponics system gets too low, bring in additional water.
The hydroponics system will be a simple timer loop to flood the beds and the wall for 15 minutes every 30 minutes. I'll also need a way to sense the amount of nutrients in the water and add additional when it's too low.
Solar
I'll get the solar system setup and that can power the pumps.
I'd also like to setup a mini-water tower. A water tank placed above the gardens means I can pump water up there when the sun is out to store potential energy. Then the control system only needs to open a valve to flood the beds. This is more efficient that storing the energy in a battery. Particularly if I can hold enough water for more than one day.
Hybrid
The greenhouse should provide an extended growing season and hopefully enough insulation with the solar heater to keep the fish warm year round. But the cost per square foot is still elevated. A hybrid system may drastically increase output at only slightly increased cost. Outside the greenhouse there will be a large garden. In v1 I want to experiment with which plants do best in each. For instance, I've had trouble with potatoes and turnips in the past because of insect damage. They may be better in the greenhouse, or external but in a hydroponic system. I've always had good luck with tomatoes, so they could be started in the greenhouse then transferred out after the first frost. I'd like to grow raspberries and my understanding is that they are pretty hardy.
Cost
I have not yet estimated the cost for the vertical wall, tools to aid with temperature regulation, setting up hydroponics, but let's call all that $1000.
At $1500, it needs to offset $75/year to be worth the investment.
I can iterate on this by extending it lengthwise.
Data Collection
- What does the temperature look like year round - important for upgrading to aquaponics.
- PH
- Nitrate
- Nitrite
2.0
This will be 14' wide (2g,3w,4g,3w,2g) by 30' long.
If the foundation approach on v1 works, I'll continue with that. If not, I will pour a foundation around the perimeter. Probably 3' deep and rising ~6" above ground. Embed a bolt about every foot and the whole thing will be bolted to this. If I'm doing this, it may also be worthwhile to add insulation.
I also want to see how the film walls hold up. I may switch over to some sort of polycarbonate here.
3.0
This should be the final revision at 21' (2g,3w,4g,3w,4g,3w,2g) x 60'.
I've always liked the idea of using part of this as living space. Specifically, doing aquaponics using a small pond to grow the tilapia with a small patio near it. With the layout above, the center 10ft would be good for this, maybe something like a 10'x10' pond with a 10'x5' patio. That takes of 25% of the 60', so I may need to extend that out to something more like 75'. But I also like the idea of a trellis over the patio, so I may not actually end up giving up much growing area for this.
Materials
Covering can be polyethylene that needs to be replaced every few years or polycarbonate. Polyethelene is available for around $0.11/sqft, where polycarbonate is going to be around $1.70/sqft. Polycarbonate also provides better insulation.
Tuftex panels look really good.