A Novel Methodology to Optimize Visual Comfort and Energy Performance for Transparent Adaptive Façades

Transparent adaptive façade components are designed to improve either visual comfort aspects or the energy performance of a building. Focusing only on one domain implies drawbacks that negatively influence the performance of the component itself. This paper hence presents a novel multiobjective methodology aimed at determining the most viable trade-off between energy performance and comfort issues for active components. This multi-objective optimization strategy was applied to a thermochromic glazing (TCG), i.e. a passive transparent façade component whose thermo-optical properties vary in response to its thermochromic layer temperature. As one of the key elements of the methodology, the influence of TCG hysteresis on visual comfort and energy performance was taken into account. The hysteresis of the TCG in an enclosed office was determined for 3 different climates and for five hysteresis widths. The results obtained show that, for all the cases analyzed, the hysteresis influence on the overall energy performance is negligible, whilst it can significantly affect visual comfort, both in terms of workplane horizontal illuminance and perceived glare.