Abstract. 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 predicted percentage of 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 a high thermal discomfort condition which is mainly come 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.
This article is about the developing parameters and relationships for selecting a proper glass window applied with film as building envelopes for buildings located in a hot climate based on its thermal performances. Thermal comfort of the occupants sitting near the glass window is the thermal performance that needed to be considered besides the heat transmission in selecting a proper type of glass to use as a glass window for the building. The predicted percentage of dissatisfied (PPD) is chosen as a thermal comfort index. 45 types of film and 1280 glass windows with film are investigated in this study. It can be shown that the thermal comfort index is dependent on the optical properties (total transmittance and total absorptance) and the overall heat transfer coefficient of glass windows with film. Glass window with film which has high transmittance shall have more discomfort due to solar radiation effect. Glass window with film which has high absorptance shall have more discomfort due to surface temperature effect. The discomfort from the surface temperature effect for double pane glass window with film is also dependent on the glass thickness other than the absorptance and the change in overall heat transfer coefficient. Expressions for predicting the performance of the glass windows with film in terms of thermal comfort are developed
The contribution of solar radiation on the global thermal comfort and local thermal comfort condition for a person sitting near a glass window in a building located in a tropical climate was studied. The effects of transmitted direct solar radiation, transmitted diffuse solar radiation, inside glass surface temperature and distance of a seated person from the glass window on the predicted percentage of dissatisfied (PPD) and plane radiant temperature asymmetry (RTA) were studied. PPD and RTA due to transmitted diffuse solar radiation and high inside glass surface temperature were decreased with the distance from the glass window. PPD was decreased exponentially with the distance from the glass window, while RTA was decreased slowly with the distance from the glass window. The findings show that PPD and RTA due to transmitted direct solar radiation striking the human body are not dependent on the distance from the glass window, but they are dependent on the magnitude and direction of the solar beam radiation incident on a human body. The results of the study would help the building designers to be able to design the interior working space for the tenant sitting near the glass window to achieve the acceptable level of thermal comfort condition.
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