Development of an electrically-switchable superinsulated glazing shutter for greenhouses in Northern Canada

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Food insecurity is widely identified as a serious and growing problem in northern and remote communities in Canada. The food supply problem could be alleviated to a considerable extent by expanding the use of greenhouses built on non-arable land near the communities where the food is needed, thereby also reducing the energy required to transport the food. However, greenhouses are typically built as transparent structures that efficiently transmit the sunlight required for plant growth. Since transparent structures do not provide much thermal insulation, a traditional greenhouse requires significant energy use for temperature control in most climate conditions, and this energy use is prohibitive in cold northern regions. The challenge to develop a greenhouse that can maintain the conditions required for plant growth while consuming only a small amount of energy has been recognized for a long time, and it has not yet been solved. This project aims to take a first important step toward practical northern greenhouses by designing and validating a high performance superinsulating glazing shutter that can be electrically switched between a highly thermally insulating state and a highly light transmissive state. The high insulation characteristic of our system arises from our novel thermal cell array of highly compressible gas-filled pockets contained within a sealed window panel. In the expanded state the panel will have a high thermal insulation value and in the compressed state the panel will be highly transmissive to sunlight, just like a conventional transparent greenhouse. The system will be able to quickly transition between the two states using only an electrostatic actuation system, without any mechanical motor parts. This technology has the potential to make cost-effective, low-energy greenhouses feasible in northern Canada. The benefits of a viable new greenhouse industry in these communities would have tremendous health, economic and social impacts.