Selection of Appropriate Light Sources in Plant Factories

This study aims to improve energy-saving practices used in plant factories by creating an appropriate cultivation environment. We examine the temperature conditions in a plant factory, which depend on the light sources. While a plant is heated by the radiation from the light source, it is simultaneously cooled through transpiration. However, there have been few investigations on this cooling effect, which occurs owing to vaporization. In this study, the temperature of the leaf surface was obtained using the energy balance equation of the leaf and both calculations of the vaporization heat. We found that the leaf temperature decreased in several cases but increased under high-illuminance, high-humidity, and low-temperature conditions. Therefore, the temperature rise of the leaf surface can be suppressed, and the cooling energy required to maintain the room temperature can be reduced by selecting an appropriate light source using the method described in this paper.