Hello everyone, I live on the plains in NE Colorado and have recently decided to construct a large greenhouse (30' x 168') to start my dream of becoming an aquaponic farmer. Where I live, in the winter it can get down to -15F and in the summer above 100F. I was wondering if anyone had any ideas on how to cost effectively heat and cool the greenhouse the least amount of fossil fuels as possible. Thanks!
...The crickets chirp and the tumble weed rolls by...hehe. I think your use of the term "cost effectively heat and cool" might have scared everyone off
Here's an idea to passively heat your greenhouse. Buy several 55 gallon barrels. Place them in your greenhouse where they will be in contact with the sun for the better part of the day. During the day the sun will heat the water in the barrels. Once the sun goes down and temperatures begin to drop the barrels will begin releasing heat.
However, -15F is pretty cold and I doubt passive heat from barrel is going to be enough to keep your fish and plants happy. You may really want to consider a wood burning furnace to help heat your greenhouse. During the summers you will probably want to invest in some type of environmental controller that monitors the heat buildup in your greenhouse. Once the monitor detects a certain temp have it connected to vents that will automatically open and fan that will help remove the hot air from the greenhouse.
Excited to hear you're living your dream man! Best of luck to you and your aquaponics venture. I have been mulling over ideas for heating greenhouses year round for quite some time now. One of the things I would like to do in the future is heating by compost. Sinking your fish tanks in the ground for added insulation and surrounding them with mulch, and as the mulch breaks down, it generates heat. Growing Power in Wisconsin utilized this concept with their green houses quite well. They also surrounded their greenhouse with giant worm composts with the walls of the compost bins right up against the sides of the greenhouse. This not only insulates the greenhouse, but the heat from the composting materials helps keep things warm. You could also run water pipes right through the center of the compost pile, and then pump it into your greenhouse to be used as radiant heating or exchange the heat right into your fish tank. As the center of a compost pile can get up to 160 degrees Fahrenheit, you could potentially heat things up quite a bit!
I also want to mention that compost could be acquired from your community for free or you could even charge people to take their compost. That would be cost effective!
This is Dr Lennard Wilson's solution: You will want a particular design where you separate your fish tanks from the green house, say in a shed. You then highly insulate that shed and your growing troughs in the greenhouse. Heat the shed to 1C-2C degrees above the target temperature for your root zone. You may need some additional heating for the green house to stay above freezing but the root zone temp is key. This really only applies to DWC where your water has minimal contact with the air in the green house. If you were doing NFT or Media beds you would need to keep the green house much warmer.
I, like Jonathan, believe that a good design will go a looong way in helping you achieve your heating/cooling goals...Heating with compost is great, but it's a fuck of a lot of work. Having an endless supply of free labor (like Growing Power) certainly helps. Still, a good idea in a particular set and setting.
Take your time researching and designing, as you will have to live with your greenhouse (and it's operating costs) for a long time.
Thanks everyone for the responses!
My nomination for the best greenhouse ever.
Check out the links to ground source heating and cooling as well.
I'm currently building a passive solar greenhouse in No. Colo. It is 15 x 25 all out of recycled, free materials. I have the three walls and roof done. Need to frame the south wall for all of the windows (vinyl, double paned sliders). It is insulated with two layers of 2 inch closed cell foam that I got from a gymnastics place that was replacing their floors. Huge rolls of the stuff, 6 to 8 feet wide by 20 to 30 feet long. I insulated the walls and the roof with it. I used steel roofing panels that were hail damaged off my dad's house to side and roof it. Corner posts are 12" beetle kill pine logs (because they were free), rafters are 2 x 6's reclaimed from a demolished deck. The roof design is a half gable or shed roof, about 12 feet on the south side and 7 on the north. After researching the supplemental heat I'll need I have decided to use an old small wood stove converted to burn waste oil. Very easily done and economical. Youtube diy waste oil stoves. I really need to take some pictures of the building and post them before it's finished.
I could use some help in deciding whether to put an epdm pond lined trough in the floor for the fish or to use a tank above ground. I'm leaning towards the trough which would allow more vertical growing above it. Which would hold more heat? Some say the ground would suck heat out of the water while others say the ground will insulate more effectively. I would like to raise warm water fish, maybe pacu or discus. Would love to hear some thoughts.
You should look into Wood Gasifiers and Pellet Stoves. I am in the process of setting up three greenhouses each one about 30'x100'. There is a Pellet Stove made by "WiseWay" it's about $1400 but it has no moving parts and can not only heat the greenhouse but heat your water with add on pipes they offer etc. Look into them, I haven't taken the plunge yet but it looks work a little peaky peak. One bag of pellets cost about 4 bucks and will last you a night or two. Good luck!
I am currently in the hvac am at a local trade school, and we have been learning about ground source heat
pumps. Look it up, they might not be the best for the dead of winter but they certainly are efficient. From Wisconsin
keep mind refrigerant is a chemical and its not hard get a leak in the system and disperse refrigerant through your organic? greenhouse.
Has anyone ever taken a look at the work of Michael Reynolds and his "earthships"? Basically, he designs buildings using recycled materials like tires and beer cans. They're supposedly very high on the self-sustaining scale, with a lot the houses not even needing external heating or cooling. I wonder if his principles could be applied to greenhouses...I'll have to look more into it. He offers a couple day workshop in Colorado that I would like to check out sometime.