Technologies of the future for the re-use of the past: the electrochromic glass

The changing needs related to ecosustainability issues stimulate all actors of the construction process to the organization of envelopes and more efficient building systems. This performance must be required not only in new buildings, but also in the conversion of existing heritage. This re-using sustainable vision, must go through a careful analysis and selection of building materials and systems related to them and their overall performance to the level of the building energy performance must be achieved. For several years, our research group is interested in innovative materials in the field of energy saving, with particular attention in transparent building components, regarding, specifically, the electrochromic glass (EC). The EC glazing elements are able to change, under user control, the color intensity of the glass itself which, going from light to dark, can shield 97% of visible light transmission and 99% solar incoming radiation. This cromatic change occurs through a chemical process of reversible oxidation-reduction that modifies, considerably and dynamically, the solar factor g (SHGC Solar Heat Gain Coefficient) and allows, at the same time, to maintain the visibility and the relationship outwards. The study concerns the city hall of Cagliari: a large Art Nouveau building (1897-1914), characterized, on all facades, by the presence of large glazing surfaces. The current system causes, due to the intense sunshine, under great un-comfort in the workplace. In the specific case study, it applies a computer simulation to compare the energetic performance of the current glazing system with those achieveble with the use of EC glass. Ultimate goal of research is the verification of the energy behavior and the level of indoor comfort reachable in traditional construction buildings with the application of innovative materials, combining the architectural value, functional recovery and environmental sustainability.