The effect of different glazing apertures on the thermal performance of Maltese buildings

Abstract

glazing areas in contemporary buildings is adaptable for a Mediterranean climate, taking into consideration Malta as the basis of this study. A total of 864 simulations have been carried out using Design Builder simulation software on three building models, namely, a 10 by 10m heavily insulated square room, on a typical 100 square metre intermediate floor corner office and on a typical top floor penthouse so as to analyze the effect of different glazing types as well as the effect of adding an automated horizontal external shading device on the energy use of buildings. An economic analysis has also been carried out. The glazing types considered were unshaded and shaded clear single glazing, unshaded and shaded clear double glazing and low-e double glazing with argon filled cavity. Results showed that in general, the cooling load is by far larger than the heating and lighting loads for the models considered, especially if glazing is facing west, east and southerly directions. Single glazing resulted in having the worst total energy consumption performance. External automatic shading proved to be the best way to reduce total energy consumption for all models, especially for those based on a square plan and for large window to wall ratios (WWRs). Using low U-value glazing types is not that effective as it was established that the overall primary method of heat gains is mostly by solar radiation and not through conduction and convection. The typical penthouse model showed that elongated building typologies have in general high total energy consumption and that glazing is not a primary factor in reducing this. For well insulated or elongated building typologies, lower U-value glazing, especially low-e double glazing with argon filled gap did result in reductions in total energy consumption, but did not perform as well as external shading. It was concluded that for dwellings with WWRs smaller than 60% it is not worthwhile to replace single glazing with lower U-value glazing. For the intermediate corner office, substantial energy consumption reductions are obtained by applying external shading for WWRs of 40% or greater, while improving the glazing type gave no practical improvement. The economic analysis showed that for the practical models (the penthouse and the corner office) it is not worthwhile for the end user to invest in any energy reduction measures, thus currently making single glazing the most economically feasible unless grants are set up subsidising the initial investment cost required.