The influence of glazing on heating, cooling and lighting use in office building retrofitting in a peninsular Mediterranean climate (1971-1980)

Abstract

Office buildings in Spain represent 33% of the total energy consumption of building stock. Most were built prior to when the Technical Building Code came into force, and hence are not energy efficient and have highly glazed façades. Doors and windows are normally the first elements to be replaced during building renovations and present an opportunity for improvement. To this end, glazing can be analyzed according to its configuration, along with any internal coatings, i.e. with or without a low emissivity layer, and through the characteristic parameters, including: thermal transmittance, solar heat gain coefficient and visible transmittance. This article analyzes the replacement of monolithic glass panes with double panes without coatings (low emissivity), by orientation. Three Mediterranean climates with different winter and summer weather severity were studied in Spain (Barcelona, Seville and Malaga). In terms of window configuration and internal coatings, for heating, lower energy consumption can be obtained with glass without coatings that has higher thermal transmittance, and for cooling, with low emissivity glass. Alternately, if the characteristic parameters are analyzed, lower heating consumption is achieved with low thermal transmittance, high solar heat gain and low visible transmittance. On the contrary, during the summer high thermal transmittance, low solar heat gain coefficient and high visible transmittance yield the best results for cooling. Therefore, it is the combination of weather from both seasons that dictates the optimal values. In lighting, lower consumption is obtained with higher visible transmittance and solar heat gain coefficients.