SUSTAINABLE NORTHERN GREENHOUSE

[Ivy Mckee]

Hi! So I'm a student studying food insecurity, and I want to develop a greenhouse for north, north canada (Specifically, Iqaluit, Nunavut) that will be inexpensive to run, make a profit, and be sustainable in the long run so that people who live in Iqaluit don't need to spend 600$ on their weekly grocery bills. However, I have zero architecture experience. I am wondering if anybody either would like to try their hand at designing such a greenhouse, or knows of any places I could find similar plans? Once I have plans, I am going to find the cost of materials, transporting materials to nunavut, building, and running costs, etc. Here are the qualifications I need:

- must be solar or wind powered

- must be very energy efficient, heat efficient, etc

- must be fairly large (big enough to provide food for a town of 7000)

- Bonus points for including materials that are easy to transport/inexpensive/available in the north. I hear iqaluit has many shipping containers because if you buy enough stuff you need to buy the shipping container also. 

If you want to help with this or know of where I can look for more resources please let me know! 

[Eric Hunting]

This is a challenging proposition given the remoteness and environment. It's a bit of an open question as to whether using plywood structures like the Wikihouse system would offer any cost advantages over more conventional greenhouse framing systems because those systems are already modular and designed for low-skill assembly. However, most off-the-shelf systems aren't intended for this kind of climate, or the unusual insolation profile of the latitude. Experimental greenhouses have been tried in the region, such as this one based on a geodesic dome with polycarbonate cladding. ( http://www.cbc.ca/news/canada/north/kale-in-the-arctic-inside-an-igloo-greenhouse-that-could-inspire-fresh-food-production-in-the-north-1.3698004 )

A greenhouse frame using the Wikihouse system is simple enough. We have a good example in the Shelter 2.0 project.

http://www.shelter20.com/cnc-files-and-instructions/

With this it would simply be a matter of applying greenhouse cladding, either in corrugated polycarbonate panel or polyethylene sheet. Mounting systems for both forms of cladding should be as readily retrofit to a wooden frame as to the more usual aluminum and steel tubing. They both tend to use various aluminum clamping profiles that are just screwed down to a frame. (  http://polycarbonate.greenhousesandsunrooms.com/wp-content/uploads/2014/02/Poly-mega-lock-glazing-system.jpg  http://www.exceliteplas.com/wp-content/uploads/2015/02/How-to-Install-the-Aluminum-Polycarbonate-Profiles.jpg  http://www.redpath.com.au/assets/images/film-clip-2.jpg  ) The former makes more sense in the climate given the need to deal with snow and high winds, however the polyethylene sheet or fabric is commonly used in experimental dynamic liquid foam or 'bubble' insulation systems ( http://www.solarbubblebuild.com/ ) intended for northern lattutides. Tefzel or ETFE, an elastomeric film, is a more high-tech greenhouse cladding that is resilient enough to be considered an alternative to glass in permanent building installations (called an 'architectural membrane') and could also be a very good choice in extreme environments. More transparent than glass, it has been most famously used in 'pillow-panel' systems for structures like the UK's Eden Project domes, but has started to turn up in commercial greenhouses because of the short-lived nature of polyethylene sheet. ( https://c1.staticflickr.com/9/8023/7557281470_509a7a8288_b.jpg ) 

Solar incidence is low at this latitude. Vertical growing systems make more sense, but this could also apply to the overall design. Glazing that doesn't contribute to gain is losing heat. (notice the added insulation on one side of that experimental dome. At least a third of its glazing is pointless. Dome homes in places like Norway and Iceland only glaze half the structure) You might only want a lean-to or half arch/dome, relying on a vertical back wall as thermal storage and insulation. Indeed, an arctic greenhouse might only need a tall vertical window-wall with an interior reflector, which is ideal for design of a dynamic liquid foam insulation system and could also well suit repurposing shipping containers. This might call for a design more akin to a trombe wall ( https://en.wikipedia.org/wiki/Trombe_wall ) than what we usually imagine for a passive greenhouse. For four months of the year, passive solar may be inadequate, however. There will need to be supplemental energy for that period. But mounting lighting vertically may be easier.

Another consideration is that most architecture in Nunavut needs to address permafrost and so is based on piling foundations. (here are some Nunavut homes https://s-media-cache-ak0.pinimg.com/originals/bf/42/fe/bf42fef6fa0eab571a355caeb2c73061.jpg http://round.s3.amazonaws.com/images/properties/10/92476/1142501_102.jpg http://www.realestateaccountingsoftware.ca/wp-content/uploads/original1-1024x576.jpg ) A number of Canadian companies specialize in the development of helical pilings for this reason. I often suggest helical piling and pin-pier foundation use with Wikihouse and similar small housing structures because of their low environmental impact and quick low-labor installation. (the common notion is that housing sustainability is about a choice of materials. I think it's about net impact with the physical impact on the landscape being just as critical, if not moreso) Some helical pilings are specifically designed for containers or pop-up container frames. Most passive solar greenhouses rely on the ground they're on as thermal storage. But this far north a permanent greenhouse may need to be lofted and insulated from the ground like all the other kinds of construction and so needs other thermal storage strategies. This is likely to be incorporated into a back wall and might use water tanking or phase-change materials. So we're really looking at something that might be better called a 'farming pod' than a 'greenhouse' because of how self-contained it needs to be. 

Though Nunavut relies predominantly on diesel fuel for its energy needs, photovoltaics have actually been deployed there and are gaining popularity. In fact, one of the interesting things about that is that the solar incidence is so low, the best way to deploy them is vertically! ( http://blog.wwf.ca/wp-content/blogs.dir/1/files/2015/12/4-600x400.jpg ) Large scale wind systems have been experimented with but haven't been generally deployed, possibly because of the issue of extreme wind speeds or because it's more expensive to build them in that enviroment, but vertical axis wind turbines of modest scale could make sense, especially since they could be integrated into buildings. 

So an ideal arctic greenhouse might be based not on traditional shapes but on employing vertical farming systems (like the zip-grow system used in that dome or living wall systems based on capillary fabrics) set in a narrow space before a very tall vertical window-wall with bubble insulation and a thermal mass or phase change back wall. This could be accommodated by a very minimally modified container that just has one side wall opened to make a window-wall. They are narrow but have broad sides and could be stacked to gain more insolation. 

[Marc Whitelaw]

Impressive reply Eric!
Just wanted to suggest checking out http://www.nursetreearch.com/ in case it might be useful ;-)

[Eric Hunting]

That's a nice approach to CNC use for a modest sized greenhouse. Both very practical, easy to assemble, and good looking. A good ready-to-go design that looks like it would nicely complement any Wikihouse build.