THERMAL AND OPTICAL PERFORMANCE ASSESSMENT OF MULTIFUNCTIONAL GLAZING UNITS Experimental and numerical investigations of Insulated Glazing Units incorporating fluid circulation and photovoltaic system

The building sector is responsible for significant global energy consumption and increased greenhouse gas emissions, especially in recent years. The increasing demand for energy for heating and cooling is one of the factors that has contributed to make more impactful this sector. Because of that it became necessary to intervene not only on the renovation of existing buildings with new materials, components, construction processes and the adoption of nearly zero energy buildings but also on the design of the building envelope, which plays an important role in controlling energy and mass flows between the building and the external environment and consequently on the well-being of users. Adaptive façades are among the most promising innovative technologies in the field of building envelope intervention. It is in this context that the content of this elaborate is placed, which is the result of work conducted for the Powerskin+ project, funded by a European Union research and innovation programme. The project involves the development of transparent components of buildings of the tertiary sector, regarding new buildings but also for the intervention of retrofit on existing ones. Specifically the aim of this work was to analyse through numerical and experimental investigations new technologies for highly efficient transparent components integrating photovoltaic and water circulation systems, in order to obtain information on the thermal and optical performance of the glazing systems. For this purpose, through the use of special software, simulations have been made on a component scale in two phases. The first phase made it possible to obtain the optical and thermal properties in static regime of multiple configurations of Insulated Glazing Units (IGU) examined, to select subsequently the best performing typologies on which to focus the subsequent simulation phase. The latter has allowed, using the Finite Element calculation Method (FEM), in dynamic time domain, the analysis of transient three-dimensional heat exchanges that characterise the components, with particular attention on the study of the thermal behaviour of the fluid in motion, defining different volumetric flow rates and analysing the temperature effects on the entire element, with and without photovoltaic system integration. This approach and the results of the analyses carried out, have highlighted the importance of acting through a physical-technical analysis on the transparent component: a fundamental element for heat gain due to transmitted solar radiation, for the luminous and visual comfort of users and critical in terms of heat dispersion; with the ultimate purpose to maximise energy performance through the study of increasingly advanced, prefabricated and modular technologies that contribute to achieving environmental sustainability objectives.