Design, Energy Use and Operation of Plant Factories in Gjoa Haven, Nunavut

In most vertical farms or plant factories with artificial lighting (PFAL), the major cost is the high energy consumption of lighting fixtures. This is not always the case in northern communities, such as Gjoa Haven, Nunavut, where a vertical farming system was deployed in October 2019 and has been operated since. With average winter temperatures below −30 °C, heating and ventilation costs often exceed lighting costs, and waste heat from light fixtures becomes a valuable energy input. A frequent criticism of PFAL systems in southern climates is the high cost of electricity and low efficiency of light fixtures to match readily available solar radiation. When the operation of PFALs was considered in remote and northern communities, which have minimal solar radiation in the winter months, instead the comparison was made between imported, gathered, and locally grown food sources. In such systems, the high ratio of heat to photosynthetically active radiation produced by artificial light sources provided a valuable heat source, rather than waste discarded to the environment. However, the latent heat produced by crop transpiration proved a challenge to conventional HVAC solutions, and the intermittent nature of traditional lighting strategies caused heating demand spikes. In 2022, a second vertical farming system was deployed to Gjoa Haven to address the challenges observed. The second system was used to grow a cucumber crop in winter 2023, achieving total energy use efficiency of 220.1 kWh/kg of fresh produce.