Double-skin façades for the refurbishment of historic buildings: Energy-economic feasibility for different types of glazing and ventilation rates

Environmental sustainability in construction is a core focus of European programs, emphasizing a built environment capable of ensuring well-being with minimal energy impact. Since Europe hosts around 30 % of the world's heritage buildings, these structures cannot be excluded from energy renovation efforts. The study focuses on improving the energy efficiency of historical buildings through a double-skin façade, analyzing thermal energy demand for space heating and space cooling in Mediterranean and temperate oceanic climates. DesignBuilder®, and EnergyPlus are adopted for energy modelling and simulation respectively. Different glazing types – single, double, double low emissivity, double reflective, thermochromic, photochromic, electrochromic, photovoltaic – and ventilation rate inside the cavity are tested, to reduce the summer overheating within the cavity. Results show that double low emissivity glazing is particularly effective in winter, with energy savings up to 26.7 kWhT/m2. In summer, double reflective glazing performs best, achieving savings up to 4.7 kWhT/m2. Regardless of the climate, natural ventilation is effective only if coupled with the right glazing type. Combining reflective glazing with proper ventilation yields, additional cooling savings are achieved, up to 7.2 kWhT/m2. Photovoltaic glazing, similar in solar properties to reflective glass, are preferable in cooling dominated climate. Finally, an economic analysis is proposed for the optimal cases. Overall, a higher cost-effectiveness is obtained in the temperate climate, but with a proper incentive rate the investigated solutions are energy-economic feasible. However, it is essential to note that approval of the renovation project by field experts is needed to ensure the preservation of the building.