Specification of glazings for façades based on spectrophotometric characterization of transmittance

Abstract

The correct specification of glazings for façades can reduce the energy consumption in buildings. The heat exchange occurs through transparent surfaces and radiation reaches the building as light and heat. Therefore, glazings significantly contribute to the heat transfer between outdoor and indoor spaces and act directly on daylighting and thermal comfort. This paper reports on the spectrophotometric characterization of glazings transmittance for the study of components of a modular façade system and its suitability for the climate of Portugal (temperate climate). The study focused on results of spectrophotometric measurements of optical properties, specifically the transmittance of some types of glazings (solar control, self-cleaning, low-e, float, and extra-clear) and two types of double glazings. The results show the percentage of transmission to ultraviolet, visible, and near-infrared regions and its importance, which enabled the analysis of the glazing efficiency regarding daylighting and the correlation to thermal performance. Subsidies and indications for the specification and adequate uses of transparent surfaces have been presented and complemented the datasheets available from the manufactures.