CANADIAN INTEGRATED NORTHERN GREENHOUSE FOR NATIONAL FOOD SECURITY

Thesis Abstract

               ABSTRACT 

The goal of this paper is to help develop a replicable design that would enable northern communities located above the Canadian 60th parallel to benefit from locally produced food on a year-round basis. In a previous report, the decision to combine a northern greenhouse with the characteristics of a growth chamber into a hybrid system, entitled the Canadian Integrated Northern Greenhouse (CING), emerged. The system would therefore act as a greenhouse during the day and benefit from the long sunlight hours during the summer. It would then transform into an insulated greenhouse during the cold dark nights and winter months. The unit will be housed in a shipping container which becomes part of the structure of the integrated greenhouse with the addition of a glazed wall and roof. A reflective panel will also be attached across the bottom of the south-facing glazed wall which will increase direct beam solar transmittance. The floor, the north wall and the side walls will mainly be insulated using extruded polystyrene rigid foam to an optimal RSI value for efficient northern buildings (RSI-10 for the floor and ceiling; RSI-5 for the walls). 

In order to reach the desired RSI value on the glazed parts during the winter, a radiant insulation blanket will be deployed when the unit transforms itself into a growth chamber. Using vertical farming principles to maximize the use of available space, the plants are placed on three different height levels using motorised nutrient film technique (NFT) hydroponic systems that track the sun throughout the day. Built with PVC pipes, each individual system hosts 7 lettuce heads for an overall production size of 483 heads of lettuce per month. LED arrays providing 25 µmol/s of photosynthetically active radiation will be incorporated to each individual hydroponic system to provide supplemental lighting. The heating, ventilation and cooling (HVAC) system was sized and partially physically prototyped. The capital cost of the first CING prototype was estimated at $35,700 leading to a price of $1.45/lettuce considering an operational cost of $4,860 (excluding maintenance labour costs) and a 10 year payback period. Considering maintenance labour costs, the price rises to $5.77/lettuce. The main barriers for the implementation of the CING (its initial cost; the availability of energy and water sources; social acceptance) will mostly be present in isolated communities rather than in the industrial sector. Awareness of the economic, environmental and health benefits will have to be done to promote this special agricultural facility that has the potential to be the world’s most volume and energy efficient enclosed food production system.