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Abstract
Recent advancements in light-emitting diode (LED) technology have improved the efficiency, profitability, and sustainability of controlled environment agriculture (CEA). In greenhouses, supplemental lighting compensates for limited sunlight, particularly in northern regions. LEDs have become an alternative to high-pressure sodium (HPS) fixtures because they convert electricity to light more efficiently, although they require higher initial investment. Continuous LED development has also enabled new systems such as plant factories with artificial lighting (PFALs) and indoor vertical farms, which rely entirely on artificial lighting. PFALs face high operating costs driven largely by the energy needed for artificial lighting and for removing water vapor produced by plant transpiration from enclosed spaces.Because energy is a major component of total operating costs in both greenhouses and PFALs, this research aimed to identify ways to reduce energy requirements and lower producer costs. The first chapter developed an adaptive supplemental lighting strategy for greenhouses that adjusts supplemental light based on the amount of natural light the plants received on preceding days and the greenhouse’s geographic location. Using daily optimal light levels reported in the literature, theoretical modeling indicated potential reductions in energy consumption and associated cost savings.
The second and third chapters focused on PFALs and examined whether adjusting light levels could reduce dehumidification costs. We tested whether increasing light to promote growth would affect transpiration and water use efficiency (WUE). Experiments produced notable trends in photosynthesis and transpiration at both leaf and whole-plant scales, revealing trade-offs between increased light, plant water use, and dehumidification demand. These results are promising but also point to challenges that require further study to quantify energy and economic impacts.
The final chapter investigated consumer perception of products grown under artificial lighting. We measured how information affected purchasing decisions and willingness to pay. While information influenced consumer behavior, it did not sufficiently increase willingness to pay higher prices for PFAL-grown products. These findings can inform future marketing strategies for PFAL producers.