The Influence of Foliage Plants on Psychological and Physiological Responses

Abstract

This research aims to clarify the significance of incorporating visual stimulation, in the form of foliage plants, into office desktop spaces. The experiments were conducted in a thermal environment with a temperature range that was slightly uncomfortable. The indoor thermal environment evaluation index ETF was used to measure the effects that brain stimulation of foliage plants have on comprehensive thermal senses. We focus on visual stimulation with foliage plants, and quantitatively measure shifts in thermal senses that affect the body. Thermal environment conditions were established with air temperature in three stages (25˚C, 28˚C and 31˚C) and the atmosphere was kept homogeneous with wall surface temperature equal to air temperature. The visual stimulations consisted of seven types of office desk image: benjamin, pothos, oxycardium, baby tears, moss ball, cacti, and no plant. At around 27˚C to 29˚C ETF, improvements in thermal sensation, as measured by thermal sensation statements, were shown to have resulted from visual stimulation benefits. Also, at around 26˚C to 29˚C ETF, improvements in comfort were shown, due to visual stimulation benefits as well, in subjects' comfortable-sensation statements. This benefit was significant when a foliage plant's green coverage ratio came between 0.75% and 4.67%, the range which does not create an overwhelming feeling from the foliage plant.

Effect of Visual Stimuli of Indoor Floor Plants upon the Human Responses

“…Therefore, this thermal sensation distribution verifies a trend that as ETF increases, thermal sensation increases correspondingly to the hot side. There is a large overlap of thermal sensation since it is on a discrete graded scale, however in comparison with the study by Kurazumi et al [11], on visual stimulation from small indoor floor plants on office desktops, for a slightly cool set temperature of 25˚C, an effective improvement to thermal sensation was verified.…”

“…Also, Kurazumi et al [9] showed that for a room it is reasonable that natural landscape factors predict an active effect of thermal en-Health vironment conditions and visual stimulation consisting of bushes and other greenery give a feeling of depth. Then Kurazumi et al [11] found that it is necessary to pay attention to the sensation of oppression from the spread of the crown when selecting a plant for an office space desktop where the visual stimulation distance between the plant and human is relatively close. In these studies, the visual stimulation in the field of view, or green covering factor, had a high numerical value.…”

“…Focusing on the regressive curve for each visual stimulation, no large difference in thermal sensation due to visual stimulation was found for an ETF higher than about 27˚C. However, when ETF was less than about 26˚C, conditions with The visual stimulation from plants was better in physical thermal environments that were slightly warm and uncomfortable, also Kurazumi et al [9] [11] studied the possibility of improvement by visual stimulation from plants in physical thermal environments that were slightly cool and uncomfortable. In previous studies, physical thermal environments that were slightly warm and uncomfortable, visual stimulation from plants was shown to be effective at alleviating the sensation of warmth.…”

“…Studies by Fukagawa et al [23] and Kurazumi et al [9] had distant visual stimulation, and target environmental stimulation conditions with the natural environment elements occupying a large solid angle in the field of view. However, studies by Kurazumi et al [11] looked at environmental stimulation that caused a sense of oppression, using close up visual stimulation placed in the personal space of an office desktop.…”

“…Then, implementing the visual stimulation of the foliage of small indoor floor plants in the office space has been shown to be an effective measure to maintain summertime cooling set at 28˚C. Kurazumi et al [11] focused on personal space in an office and with the air-conditioning temperature set to 28˚C, they examined subjects in a range of mildly uncomfortable thermal environments. An interior thermal environment evaluation index conduction-corrected modified effective temperature (ETF) [10] of around 27˚C -29˚C, was shown to improve thermal sensation resulting from the reports of the visual stimulation of small indoor floor plant foliage.…”