On the use of dynamic film to improve the thermal and solar performance of multiple glazing units. Preliminary testing and assessment

Transparent systems play a crucial role in modern buildings affecting energy performance, visual and thermal comfort and interrelation between external and indoor environments. Due to the highly daily and seasonal variations in outdoor conditions and indoor requirements, dynamic façades represent a viable solution for optimizing overall building performance. This paper explores the potential of moveable transparent/opaque films placed within the gap of double glazing units. A selection of transparent and opaque polyester films was screened, and the optical properties and thermal emissivity of the selected samples were measured using laboratory equipment compliant with relevant international standards. Depending on the films, the solar transmittance ranged from 0 % to 75 % while the solar reflectance varied from 7 % to 89 %; the emissivity values were within the 0.10–0.80 range. When applied to double glazing units, the thermal transmittance decreased by up to 1.2 W/m2K in conventional glazing systems and by up to 0.3 W/m2K in low emissivity glazing systems, respectively. The solar properties, namely the solar factor, of the assembled units were extremely scattered, depending on the characteristics of both the glazing unit and the film, as reported in the results. The numerical analyses carried out at building scale on a reference residential case study, demonstrate that this technology can achieve up to 8 % energy savings for space heating and over 80 % for space cooling, depending on the glazing unit characteristics, the activation strategy and the climatic conditions within the Italian context.