Energy, environmental and economic analysis of windows’ retrofit with solar control films: A case study in Mediterranean climate

The incorporation or the replacement of materials in buildings may decrease the energy use during the operational stage but increase the embodied energy in a building's life cycle. In this study, three different solar control films (SCFs A, B and C) with application on the existing windows of a building are investigated through an energy, environmental and economic perspective over a defined life cycle period. The full replacement of the existing window with a new one is also analyzed as an alternative retrofitting solution. Retrofitting solutions with higher light-to-solar gain ratios showed higher energy savings during the use stage by decreasing the solar gains in a higher proportion than the decrease of the visible transmittance. The best retrofitting solution, SCF C, showed a life cycle energy (LCE) (embodied plus operational energy) and a carbon footprint of 4447 MJ/m2/40 y and 380 kgCO2eq/m2/40 y, respectively, whereas the least performant solution, new window, showed a LCE 1.5 times higher than the average of the three SCFs. The higher LCE value of the new window was found to be related to the higher value of the embodied energy when compared to that of the three SCFs (∼9 times higher than the average of the films).