External condensation on windows

Surface condensation on external window surfaces has been given very little attention while internal surface condensation has been the subject of considerable research. In hot-humid climates, atmospheric condensation on the external surface of windows is a problem for air conditioned buildings. Windows internal surfaces are exposed to cold indoor air temperature while the external surfaces are exposed to hot and highly humid outdoor air. Consequently, external surface condensation becomes inevitable. In this paper, the condensation process at the external surface is analysed and a quantitative basis for predicting atmospheric water vapour mass condensation rate has been developed. The results of this study have been shown to be useful in assessing window potential for external surface condensation and means to predict it at the early stage of the design where most irreversible decisions are made.