Performance rating of glass windows and glass windows with films in aspect of thermal comfort and heat transmission

This article is about a study on glass window and glass window with film of different types in aspect of thermal comfort and heat transmission. Different types of glass window, clear glass, tinted glass, reflective glass, double pane glass, and low-e glass were investigated. Films with different spectral optical properties were then adhered to the glass windows of different types and studied. The analysis was done based on the outside design weather condition which selected from 12 years of Bangkok meteorological data. Predicted percentage of dissatisfied (PPD) was selected as the thermal comfort index. The relative heat gain (RHG) based on local weather condition was selected as the heat transmission index. The PPD can be subdivided into the PPD due to surface temperature effect and the PPD due to solar radiation effect. The analysis indicated that, for most of the glass windows considered except the reflective glasses, the values of PPD due to solar radiation effect were much larger than the values of PPD due to surface temperature effect. And the most discomfort condition occurred when using a clear glass as window. Adhered films to the glass windows caused the PPD due to surface temperature effect increase and cause the PPD due to solar radiation effect decrease. It was also found that the PPD values due to solar radiation effect for glass windows and glass windows with films were varied linearly with the total transmittance of glass windows and glass windows with films. The PPD values due to surface temperature effect were varied with the total absorptance of glass windows and glass windows with films in an almost linear fashion. The heat transmission index, RHG, based on chosen design weather condition can be subdivided into the RHG due to conduction effect and RHG due to solar radiation effect. The analysis indicated that the values of RHG due to solar radiation effect were larger than the values of RHG due to conduction effect for all glass windows and glass windows with films considered in this study. Adhered film to the glass windows resulted in lowering the relative heat gain due to solar radiation in the amount corresponding to the film properties. But the film had very few effect on the relative heat gain due to conduction. The relative heat gain values were varied linearly with the total transmittances of the glass windows and glass windows with films. The relative heat gain values were also varied inversely with the absorptances of glass windows and glass windows with films in a linear fashion. (c) 2004 Elsevier B.V. All rights reserved.