Availability of Heat Conduction for Environmental Control Method to Improving Thermal Environment and Preventing Oversensitivity to Cold and Air-Conditioning Disease on Female Office Workers

The purpose of this study is to demonstrate the effect localized heating of the feet has on physiological and psychological reactions of female in an air-conditioned environment in summer. In Japan, female office workers wear less clothing than their male counterparts. In an air-conditioned office space in summer, female conducts thermoregulation by putting on cardigans, etc. but this action does not greatly contribute to improving conditions for the legs and feet, the lower extremities of the body. The improvement of sensational and physiological temperature by localized warming of the body can contribute to a healthy working environment for female office workers, their safety, and a reduction in air conditioning’s energy expenditure. We used the indoor thermal environment evaluation index ETF to investigate the effect localized heating of the feet has on human physiological and psychological response in an air-conditioned environment in summer. The result of heating by means of heat conduction via the sole of the foot was expressed more strongly as a psychological effect than as a whole-body physiological effect. Heating by means of heat conduction via the sole of the foot was a thermal environment factor that compensates for a low temperature in whole-body thermal sensation and whole-body thermal comfort. The effect of heating due to heat conduction via the sole of the foot was expressed in the change in sole-of- the-foot skin temperature. Applying slight heat conduction by means of heating via the sole of the foot demonstrated the result of improved whole-body thermal sensation and whole-body thermal comfort.

Effects of Outdoor Thermal Environment upon the Human Responses

In a summer outdoor space, the influence of short-wave length solar radiation on the human body is strongly apparent, heat is retained in the body, and the risk of heat disorders such as heat stroke increases. To avoid this, it is essential to seek shade to avoid the influence of short-wave length solar radiation. In addition, natural ground surfaces such as green spaces and water surfaces are useful in reducing the air temperature. It is indispensable to consider climate mitigation effect of outdoor space. The purpose of this study is to clarify the influence of the thermal environment of an outdoor space on the human body in rural and suburban regions where paddy fields remain. Subject experiments were conducted to examine the relationship between the thermal environment evaluation index enhanced conduction-corrected modified effective temperature (ETFe) in an outdoor space and the physiological and psychological responses of the human body. Experiment sites were selected with consideration for the natural ground surface such as bare ground where the surface is gravel or soil;paved ground such as concrete, asphalt or blocks;green areas covered in plants;and water surfaces, as well as the sky factor due to buildings or trees etc. and the proportion of the solid angle of components of greenery and water etc. comprising the solid angle of the total celestial sphere. A ground surface feature with a high heat capacity may promote sensation of hot and deteriorate the thermal sensation. A landscape of thick vegetation with a high green factor may have a strong feeling of confinement, which can make it somewhat hot and somewhat uncomfortable thermal environment due to the sense of stagnation. Compared with the urban environment, it is conceivable that the difference in the perceptual environment, whereby it is subconsciously assumed to be a comfortable thermal environment, had an effect in the rural and suburban regional environment, resulting in an ETFe lower than the upper limit of comfort in a summer urban environment.

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

The biophilia hypothesis maintains that animals, which bring benefits for human survival, evolve adaptively to cause a positive emotional response or actions in the human evolution process. When connected in an advantageous environment for survival, effective relaxation and recovery from fatigue are brought about as further physiological functions, rather than a simple stress-free situation. The aim of this study is to clarify the significance of the visual stimulation of indoor floor plants placed in an office floor space. We examined how the green covering factor and gaze distance to indoor floor plants placed on the floor influenced thermal sensation. The thermal environment conditions were set at 3 levels, 25°C, 28°C, and 31°C and the floor and air temperature were homogenous. We set up 8 office floor plans that had no visual stimulation and used indoor floor plants including pachira, monstera, butterfly palm, yucca elephantipes, weeping fig, umbellate, and snake plant for a visual stimulation. The gaze distance, measured from the center of the subject presented with a visual stimulation and the center of the plant, was set at 3 distances: 2.0, 4.5 and 8.0 m. When the conduction-corrected modified effective temperature (ETF) was below 26°C, the visual stimulation of the indoor floor plants umbellata and monstera, which have a silhouette with low leaf density and rounded leaves, were shown to mitigate the sensation of being cool. The visual stimulation of indoor floor plants with rounded leaves, such as, pachira, monstera, weeping fig, and umbellata, were shown to decrease the feeling of discomfort. For a gaze distance below 4.5 m, a green covering accounting for less than 5% was shown to be necessary for mitigating the sensation of being cool and improving the feeling of discomfort.