• Energy Research

Limited cultivation areas in major cities have led to the possibility of vertical farming (the practice of growing crops in vertically stacked layers). However, one of the drawbacks of vertical farming is the limited availability of solar energy at the lower shelves. This study presents a model for predicting the annual sunlight availability on vertical shelves. The model uses the shelf’s structure, orientation, hourly solar radiation, and sunshine duration as inputs to Rhinoceros 3D or RHINO (a 3D computer graphics and computer-aided design application software with the Grasshopper plug-in). The calculated solar energy available at each level of the shelves from RHINO was converted to photosynthetic photon flux density (PPFD) and daily light integral (DLI) using spreadsheet software. This study investigated a vertical farm, in Chiang Mai, Thailand, with six parallel shelves at 1-meter spacing. Each shelf contained three levels with a spacing of 0.5 meters. Both north–south and east–west orientations were investigated. The model could predict PPFD and DLI at every level on the considered shelves. The north–south orientation provided uniform PPFD and DLI throughout the year. The top level of the shelves experiences the highest PPFD (1,949.86μmol*m-2*s-1) and DLI (36.80 mol*m-2*day-1). The PPFD and DLI values at the middle and bottom level were approximately 60% and 50% of the values at the top level, respectively. This information can be used for cultivation planning when considering vertical farming in urban areas. This study provides a sustainable means for future food production.

Limited cultivation areas in major cities have led to the possibility of vertical farming (the practice of growing crops in vertically stacked layers). However, one of the drawbacks of vertical farming is the limited availability of solar energy at the lower shelves. This study presents a model for predicting the annual sunlight availability on vertical shelves. The model uses the shelf’s structure, orientation, hourly solar radiation, and sunshine duration as inputs to Rhinoceros 3D or RHINO (a 3D computer graphics and computer-aided design application software with the Grasshopper plug-in). The calculated solar energy available at each level of the shelves from RHINO was converted to photosynthetic photon flux density (PPFD) and daily light integral (DLI) using spreadsheet software. This study investigated a vertical farm, in Chiang Mai, Thailand, with six parallel shelves at 1-meter spacing. Each shelf contained three levels with a spacing of 0.5 meters. Both north–south and east–west orientations were investigated. The model could predict PPFD and DLI at every level on the considered shelves. The north–south orientation provided uniform PPFD and DLI throughout the year. The top level of the shelves experiences the highest PPFD (1,949.86μmol*m-2*s-1) and DLI (36.80 mol*m-2*day-1). The PPFD and DLI values at the middle and bottom level were approximately 60% and 50% of the values at the top level, respectively. This information can be used for cultivation planning when considering vertical farming in urban areas. This study provides a sustainable means for future food production.

This paper investigates heat load due to LED lighting of in-door strawberry plantation. A double-chamber experimental room was designed and constructed at Chiang Mai University, Thailand. There are 180 strawberry plants inside the inner experimental room. Air temperature and moisture of the room can be adjusted using an air conditioner. LED tubes was used to supply light for photosynthesis of the strawberry plant. The air temperature, air moisture, and condensed water from evaporator were measured. Using energy balance and mass balance equations, it was found that, during the use of LED lighting, the condensed water from the experimental room was increased. Calculated heat load of the room were also increased. Approximately 60% of the heat load is from condensation when there is no lighting load. While providing lighting from LED, heat loads from LED and condensation can be almost 100% of total heat load. Increased condensation heat load is the result of evapotranspiration by strawberry plant. Keywords: Heat load, LED, In-door plantation, Strawberry

This paper investigates heat load due to LED lighting of in-door strawberry plantation. A double-chamber experimental room was designed and constructed at Chiang Mai University, Thailand. There are 180 strawberry plants inside the inner experimental room. Air temperature and moisture of the room can be adjusted using an air conditioner. LED tubes was used to supply light for photosynthesis of the strawberry plant. The air temperature, air moisture, and condensed water from evaporator were measured. Using energy balance and mass balance equations, it was found that, during the use of LED lighting, the condensed water from the experimental room was increased. Calculated heat load of the room were also increased. Approximately 60% of the heat load is from condensation when there is no lighting load. While providing lighting from LED, heat loads from LED and condensation can be almost 100% of total heat load. Increased condensation heat load is the result of evapotranspiration by strawberry plant. Keywords: Heat load, LED, In-door plantation, Strawberry