Daylighting performances of different advanced glazing systems: test cell measurements and analysis

The influence of daylighting on the energy performances of buildings is widely recognised, as well as its benefits on human comfort and health. The research aims at demonstrating the potentialities and the limits of advanced glazing technologies compared to conventional solutions, in order to spread out the penetration on the market of more efficient components and systems. The performances are evaluated by a experimental campaign, carried out installing different glazing systems in three outdoor test cells. The cells are identical in geometry, used materials and dimensions of the windows. Different glazing systems were tested: electrochromic glazing units, interpane fixed reflecting lamellae, internal moveable venetian blinds with lamellae with high regular luminous reflectance, capillary transparent insulation with a diffusing layer. A standard glazing and internal blind was installed as reference condition. Each room was equipped with a number of illuminance sensors in order to evaluate the luminous climate on the basis of daylight availability, also the external global horizontal illuminance was measured with the same time step. The monitoring was carried out during the spring equinoxes, the measurements were taken with a time step of six minutes along all the day. Sunny and cloudy days were monitored in order to have a complete set of data to assess the advantages of each system and to make reliable comparison respect to a conventional transparent systems. According to the results, the dynamic systems have good performances in terms of lighting levels and uniformity respect to the standard solutions. The static glazing units, even if show a good behaviour in several climatic conditions, cannot ensure the optimal luminous quality always, being their performance affected by characteristics and the design of the transparent and reflecting components.