An Investigation on the Human Thermal Comfort from a Glass Window

The effect of the glass window on the thermal comfort of a person sitting near the glass window is investigated by performing the experiment in a test room. A clear glass window and a tinted glass window are chosen to be the test windows in this study. The index chosen to describe the thermal comfort is the percentage of people dissatisfied (PPD). The important parameter for evaluating the human thermal comfort condition is the mean radiant temperature. The mathematical model for predicting the mean radiant temperature is presented. The predicted mean radiant temperature and the mean radiant temperature evaluated from the operative temperature are compared. The agreement is good. It is found that the mean radiant temperature, the predicted mean vote (PMV) and the PPD are all dependent on the transmitted solar radiation and the surface temperature of the glass window. Higher value of the mean radiant temperature yields higher value of the PMV and the PPD. The room with a clear glass window installed has high thermal discomfort condition mainly from the solar radiation. The amount of the thermal discomfort is directly varied with the amount of the transmitted solar radiation. For a high transmittance glass window, the thermal discomfort due to solar radiation is greater than the thermal discomfort due to surface temperature. For a low transmittance (high absorptance) glass window, the thermal discomfort due to surface temperature becomes important when compared to the thermal discomfort in the part of solar radiation.

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