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Objective of this research is to evaluate the car cabin environment on the driver's comfort and fatigue. In the first experiment, subjects were exposed to 4 conditions, performing 3 kinds of simulated driving task. The visual recognition and reaction task developed in this study was adequate to be used for evaluation of driver's performance and fatigue. When the break up time (BUT) of subjects' eyes gets shorter due to indoor environment, their performance would become lower. Female subjects were more sensitive in eye comfort and visual fatigue than males. In the second experiment, subjects stayed for 90 minutes in a car cabin with 2 humidity conditions, performing the Visual recognition and reaction task. Humidity in car cabin affected human skin moisture and humidity sensation. BUT at low humidity was shorter than at high humidity although no statistically significant difference was observed in eye dryness sensation and visual fatigue.

Thermal comfort for car occupants is important factor for automotive design. We have been developing efficient solar reduction glass for vehicles. We also developed a numerical simulator to predict and evaluate the thermal environment and thermal comfort in vehicles. In this simulation, firstly distribution of solar radiation energy through the glass can be calculated actually, and then temperature and air flow distribution, and human comfort can be computed by a combined analysis of CFD (computational fluid dynamics), thermal radiation and body temperature control model which corresponds to shapes of a vehicle and human body. The thermal environment differences between solar reduction glass and normal glass should be clear, which makes the effects of functional glass clear from the view point of human comfort. We can calculate comprehensive situations and indices of thermal comfort evaluation.

The transmissive and reflective performance of the glass according to the radiation sources are discussed for the accurate evaluation of the solar radiation through the glass window. They are quite different in radiation sources such as solar radiation from the sun or infrared solar lamps in the experiments because of the spectral properties of both glass and radiation sources. It is also discussed how differences of transmissive and reflective performance of the glass affect thermal comfort of car occupants. A numerical simulation method based on the comprehensive combined analysis with thermoregulation model within a human body, radiation models including thermal radiation and solar radiation, and CFD (Computational Fluid Dynamics) is conducted for this purpose.

Thermal comfort for car occupants is important factor for automotive design. We have been developing the numerical simulator for the prediction of the thermal environment and thermal comfort in vehicles. In the previous paper, the comprehensive combined analysis method with multi-node thermoregulation model, radiation model and CFD (Computational Fluid Dynamics) is proposed. In this paper, the applications of this method to car occupants are presented. We focused on investigating the effects of glass properties on thermal environment of compartment and thermal comfort for passengers. The calculated results were compared every part of glazing, front windshield, front sidelite and rear sidelite in summer condition. It was found that the differences of air temperature between normal glass glazing and functional one are not so much but the differences of human feeling are significant. Further more, the effects of functional glass on the reduction of air-conditioning power are simulated.

A numerical simulation method is presented for the evaluation of thermal comfort of car occupants under direct solar radiation. Present method is based on a comprehensive combined analysis with multi-node thermoregulation model, which is integrated by the 65-node thermoregulation model (65MN: Multi Nodes) based on the Stolwijk model, radiation model including thermal radiation and solar radiation, and CFD (Computational Fluid Dynamics). This paper focuses on the outlines of each numerical simulation method and discusses on the human body shape for predicting accurate boundary conditions of thermoregulation model. Applications of this method to car occupants are presented in the Part 2.

Nearly all of the commonly used comfort predictors assume that the occupant is in a homogeneous environment, and are not fully effective in situations where this is not the case. In typical vehicle spaces, one commonly observes vertical temperature differences, radiant asymmetry, local air flows, and local body cooling. The purpose of this study is to describe a method for measuring non-uniform thermal environments using a new thermal manikin with controlled skin surface temperature. The manikin and its control logic are described, and an equivalent temperature based on the thermal manikin (teq) is proposed and discussed. To calibrate these methods, fundamental data were collected. For example, the clothed thermal manikin was tested in thermally non-uniform vehicle environments as created by solar radiation and HVAC system. The manikin-based equivalent temperature (teq) is shown to be effective at accounting for the effects of asymmetrical environmental conditions.