Effect of Daylighting and Artificial Lighting on Photosynthesis and Chlorophyll Contents of Indoor Plants

Countries around the world recognize the importance of the lighting energy saving. Many comparative studies on the daylighting and the artificial lighting were realized. However, these comparisons were not precise as the weather varied from hour to hour. The performance of the daylighting and the artificial lighting must be evaluated in the same condition. In this study, two experiment chambers consisting of daylight and artificial lighting were made. In order to make the same illuminance condition, 12 flourscent lamps (32W) were used with dimming-controller. The same illuminance of two chambers could enable the precise comparison experiment. In the photosynthesis, the increasing rate of the plants in daylighting chamber was higher than that in artificial chamber, and in the chlorophyll it was the same. The reason for this result is shown by the difference of spectrum energy. The light-absorbing pigments of plant need the spectrum of the large wavelength. The spectral energy of daylighting consists of ultraviolet, infrared and visible rays. However, the spectral energy of fluorescent lighting is high only at some specific wavelengths.