Most stable year round greenhouse in 5b climate

I am located in Belleville Ontario Canada and we are classed as 5b growing climate which means winter temps of - 20 to - 10 F / - 29 to - 23 C

I need to build a greenhouse that is very very stable at 72 to 74 degree year round. I'm not sure that this is the right place to post but I'd appreciate any info or pointers to a better place for info.

The idea so far is a relatively small cold sink earth bermed greenhouse with a heat pump to control temperatures but until I break ground nothing is firm yet.

thanks

Why such a specific temp? Are you raising something specific or doing aquaponics? What about light exposure?

I present the Walapini: http://www.bensoninstitute.org/Publication/Manuals/Walipini.pdf

or the growing spaces domes: http://www.growingspaces.com/

Add a heat pump if you can afford it, but I would build a rocket mass heater with water tanks as part of the mass as the primary heat even then. The cost of the rocket stove will pay itself back really quick--it takes a LOT of energy to heat a greenhouse.

R Scott wrote:Why such a specific temp? Are you raising something specific or doing aquaponics? What about light exposure?

I present the Walapini: http://www.bensoninstitute.org/Publication/Manuals/Walipini.pdf

or the growing spaces domes: http://www.growingspaces.com/

Add a heat pump if you can afford it, but I would build a rocket mass heater with water tanks as part of the mass as the primary heat even then. The cost of the rocket stove will pay itself back really quick--it takes a LOT of energy to heat a greenhouse.

thanks for the links. At a quick glance they look spot on target.

To answer why the specific temp, yes I am raising something specific. I own operate a retail marine aquarium store and am looking to move in to salt water aquaponics with a focus on rare corals. We already grow a large portion of our inventory in house and are now looking to take it to a new level. It has never been done in Canada to my knowledge although there are greenhouse coral farms scattered around the states.

I like rocket stoves but this has to be able to be computer regulated. A heat pump is the no#1 choice but I want to build a greenhouse that will need to use the heat pump as little as possible.

This project is going to be a combination of age old methodology and best of the new tech.

So far...

earth bermed on three sides
glazed south wall
evacuated tube hot water solar collectors feeding buried storage tanks and radiant coils.
Primarily PV hydro with the grid to suppliment and generator backup
all LED lighting over the grow out tanks
all DC voltage pumps

What I'm trying to decide is what type of earth bermed design to build and what temperature control mechanism to build into it.

Greenhouses appeal to me
The soap bubble foam insulation http://solaroof.org/wiki/SolaRoof/DoubleTunnelGreenhouse is interesting but I have a design in my head that is similar but uses a double layer of rigid glazing that can be filled/emptied in minutes with styro beads resulting in an insulated R20+ glazed wall at night.

I'm not sure that I shouldn't just forget the greenhouse and build a fully earth bermed building with a super insulated roof. That is why I am here. I thought folks like you could direct me to some of the better greenhouses so I can make that decision.

well I love the Walipini and it may adapt well to my ideas. It is basically a variation of what I was already thinking on but it is interesting to see something so simple and it has made me ask myself why not that simple? The roofs shallow slant would require a blower to evacuate the styro beads where as my current design uses the blower only to fill the glazing and uses gravity to drain them but other than the cost of buying a 2nd used furnace blower it doesn't add any degree of complication to it and if I get creative with venting I suppose one blower will do.

If I can get a base line temp of 50 degrees in the structure and then use the evacuated tube solar collector, storage tanks and in floor radiant heat to get me to 65 degrees than the heat pump only has a small job to do. Summer concerns me because it gets hot here. Coral need lots of light but heat kills them fast.

I'd be interested in any ideas to actively cool such a structure with out blocking the sun.

What is the variation you were already thinking of?

The Walipini looks like a take on the Passive Solar Thermal Greenhouse idea. It will use the thermal mass of the earth to help capture and store the energy from the sun during the day and release it back into the enclosed space at night. The angle of the translucent material being important that it is perpendicular to the angle of the sun at Winter Solstice for maximum winter soalr thermal energy accumulation.
I'm at work and don't have any links with me, but if you haven't already, do some searches on Passive Solar Thermal Greenhouses. There's lots of good information on them and I remember specifically some info on them in cold climates.

Sounds like a cool project you have going on! Best of luck to you!

Steve White wrote:
I'd be interested in any ideas to actively cool such a structure with out blocking the sun.

http://www.mb-soft.com/solar/intake.html

and with the radiant water tubes. You can set up the heat pump to pump both ways.

R Scott wrote:

Steve White wrote:
I'd be interested in any ideas to actively cool such a structure with out blocking the sun.

http://www.mb-soft.com/solar/intake.html

and with the radiant water tubes. You can set up the heat pump to pump both ways.

thanks, good link.

earth tube heating/cooling is quite popular and had been high on my list but this guys take on it is different than any others I've seen and I like it. Obviously an engineers take on the concept ... a long winded rambling engineer lol, but an engineers take is exactly what I had always wanted to see applied to this concept. The typical earth tube system had always struck me as a very "wing it by ear" idea and that does not appeal to me.

I would have to say that after reading this an earth tube will definitely be a part of the design.

a cross between a walipini and mike oehlers design (just add a cold sink trench) and for heating, i would recommend the type of subterranean heating and cooling systems such as the ones being used at the rocky mountain permaculture institute based in basalt, CO

At your latitude, I am not sure that the slant of the glazing would be particularly shallow. Using the Benson Institute's calculations, Belleville is at about 44 degrees North Latitude, add 23 and you get 67 degrees. You would need to modify the design to incorporate that pitch, but it shouldn't be a big deal. It would end up looking like a passive solar home at that latitude, with the South-facing window wall slanted at the optimum angle for Winter heat gain.

Because of your requirement for stable temperature, perhaps your idea of using earth berm with a super-insulated roof may be the best idea. Some solar tubes would provide a lot of natural light without loosing much heat.

Since your major concern is keeping the water temperature stable, you may not need to be overly concerned with the air temperature of the facility, as long as the tanks are well insulated and the top covered with insulation when there is no need for light.

Perhaps some clear bubble insulation could be floated on the water to keep the water temperature stable and improve the tanks' solar collecting abilities?

Steve,
Please, let us know what is your main concern (for given setup)?
Light/Heat/Electricity (in other words what is the main cost to rice your corals?)
My understanding is that if you have greenhouse then evacuated tubes, pipes, pumps, controllers and heat storage are waste of money.
However, it might be an option if you build super insulated building with no glass wall to south which is main heat loss reason during the night or on cludy day.
It looks like too much of everything, what will end up in high investment.

BTW, very interesting topic.

So it has been coming together in my head.

I was thinking along the lines of this http://www.youtube.com/watch?feature=endscreen&NR=1&v=9IYKzpVPMBw. I didn't like the venting system in this design though so I thought that I could do a double glazing using Solex (as seen here) .

Now I'm thinking that a simple rectangular fully earth bermed on 3 sides with glazing all down the south side. It would look more like a small oddly proportioned earthship from the outside. The roof could be super insulated using a living roof or a steel roof with straw bale insulation. A water collection system would feed a buried reservoir.

In either case the cold sink similar to the one shown in M Ohler's book was to be used. I plan on a foot deeper version with more gravel to bring it up to the correct standing height and while the cold sink will still run down the south wall it will have fingers coming off it in the direction of the north wall. Essentially the coral tanks would be on raised earth beds. Isles ( the cold sink) would allow me to walk all the way around 3 sides of the 4' wide x 12' long coral beds. Under the coral beds in the raised earthen platform I'll bury radiant coils hooked up to the storage tank for the evacuated solar collector. At the bottom of the cold sink I'll install drainage tile which will connect to a sump pump.

All of the exposed ground/dirt will be sprayed with a fibre reinforced thincoat of concrete very similiar to the method they use when building the ecodome homes. On the U.S. site they show fences and planters built using their sprayer and basalt reinforcement clothe and that would be my approach. The coral tanks them selves will be made of plywood coated in Williams low voc 80% solids by weight 2 part epoxy and standard fiberglass reinforcing cloth. They will need to be built in place.

The south glazing will be 60 degrees and use Solexx with one layer on top of the 2x6's that form the glazed wall, and one layer on the bottom, which would be inside the greenhouse. A blower system with a manifold up top and a collector down below would blow styro beads ( like are sold/used to fill beanbag chairs) up the manifold to fill the cavities between the studs and glazings forming an insulated wall. Gravity will empty it and it is something that can be easily automated by either a thermostat or photo cell. The bottom door that opens to allow the beads to fall into the collection chamber could be powered by a 12v DC power window module from the junkyard. They are cheap, have plenty of torque and the drivers side on most imports has an auto stop at full open and full closed simplifying the design.

A ground source heat pump will supply the backup heat and it will be installed in a manner that will allow the addition of more greenhouses to be serviced by the one heat pump. I am going to have to spend some time and figure out the best proportions for the design. I will not be targeting my greatest amount of solar gain during the day time as I am more concerned with heat loss at night. That is the case for all passive solar designs but I will be clearly leaning towards heat conservation and stability.

Earth tube heating/cooling would be implemented as per http://www.mb-soft.com/solar/intake.html

No matter what I do a green house can not supply all of the light I need and I will have to supplement with a lighting system. Corals use a lot of the blue spectrum (420-460nm wavelength) and that is quite strongly filtered out by most any glazing. Even a plain single pane of glass removes a significant amount so the result is that a greenhouse is capable of providing me with only approx 30 to 50% of the light I need. That is still a considerable contribution considering how much hydro is commonly used to power the HID lights in most coral farms. My intention is to use array's of 3 volt LED's with a DC controller so that I can wire them to a PV/battery system. I should be able to get away with producing only the light spectrum of 420 to 460 nm with the ambient light of the greenhouse supplying the rest of the spectrum. Only hands on experience will tell that tale for certain. Regardless, lighting is something every coral farmer is an expert on and it can be scaled as required.

I'll use DC lighting (for ambient/working light) and DC motors though out the design and attempt to operate completely off solar power. For backup it will be on the grid and have a generator.

No single attribute of this idea makes financial sense for this project on it own. But the combined low cost of construction of the building, even lower cost of future greenhouses due to the shared heat pump, low heating costs, ease of expansion and reduced lighting requirements make it appear feasible to do. I am not an engineer though and am in fact mathematically dyslexic so there will be precious little for me to go on except for experience and gut instinct.

My instinct is that it will work. There is nothing new here as these are all common technologies that are just being applied for a new purpose.

A lot of it depends on finding a suitable site to build on. I could build this on the ground and berm it up after construction if need be. That would mean the additional cost of cement walls and foundation though. That is money that could better be used in other parts of the project.

Some additional thoughts are to build a super insulated utilities building that will be the center of the system. It could be quite small fully earth bermed and house the connection to the grid (so I only have to pass one hydro inspection) the heat pump, the electronics and distribution for the power, the generator, the sump that the drainage pipes in the cold sinks feed to, the storage tank(s) for the evacuated solar collector(s), the earth tube heating/cooling collection/distribution system and any other mechanical system. I'd obviously need to run heavily insulated pipes and tubes to distribute the air and fluids from it to the greenhouse but it would allow greenhouses to be added as money or demand allowed forming little clusters. The single systems would be much easier automated and regulated to serve the needs of multiple greenhouses this way.

Now all of that said we have just requested a walk though on a commercial building in the city and if it is a go I'll be changing gears completely.

"Now all of that said we have just requested a walk though on a commercial building in the city and if it is a go I'll be changing gears completely."

Good to know you are not too committed to a particular solution.

Andrew Parker wrote:"Now all of that said we have just requested a walk though on a commercial building in the city and if it is a go I'll be changing gears completely."

Good to know you are not too committed to a particular solution.

lol, is that sarcasm?

I have a strong preference for the greenhouse idea. I would like to build a $0 mortgage modified earthship first and then the greenhouse and build from there. Get some goats and chickens and build a more conventional greenhouse for food.

Fact is business is business though and with the right commercial location we will go from being a saltwater aquarium specialty store to a full service pet store/bulk pet food company. Not really my goal only a fool turns their back on opportunity in todays market. Time will tell but in the mean time I will continue planning my off grid life.

Nope, no sarcasm in my statement. It takes some discipline to not get carried away with an idea. I like to see a good idea through to the end, but there are a lot of factors involved in life and often it is better to be flexible. I have seen more than a few recently divorced men (sometimes women) living alone in a not-quite-finished dream home.

Good luck with your business. I hope you are able to try out your greenhouse idea.

just thought i would add as the guy in the video mentioned oxygen to co2 ratio... having a good amount of fungi in your greenhouse can do a great deal to replace oxygen created by the plants with CO2

Hi there!

We are located in mount forest area and are also thinking of a year round stable " hot house" grow space. The geodesic dome design seems to be most efficient however we aren't carpenters or architects so simple would be better... Then theres the north wall insulated, 5 wall polycarbonate glazed option... Simpler to construct but the angle of the glazing is best at around 40 degrees for our area and this would require a very tall north wall which means money. For now we acquired a regular heavy duty cottage style, clear , polycarbonate structure which we are going to convert. We aren't to far away from your place and would be happy to toss ideas around being that we have the same zone! Ttys!

Jesse Meijer wrote:Hi there!

We are located in mount forest area and are also thinking of a year round stable " hot house" grow space. The geodesic dome design seems to be most efficient however we aren't carpenters or architects so simple would be better... Then theres the north wall insulated, 5 wall polycarbonate glazed option... Simpler to construct but the angle of the glazing is best at around 40 degrees for our area and this would require a very tall north wall which means money. For now we acquired a regular heavy duty cottage style, clear , polycarbonate structure which we are going to convert. We aren't to far away from your place and would be happy to toss ideas around being that we have the same zone! Ttys!

I once read a book entitled "Solar Greenhouse" that had lower-costing passive solar ideas.

Steve, how is your greenhouse now? I'm trying to build something similar.