Evaluation of optimal thermo-optical properties for electrochromic windows in current and future climate scenarios: A multi-locations optimization

The technological advancement of innovative electrochromic (EC) technologies is fuelling the spread of new devices characterized by different thermo-optical properties. This wide range of possibilities poses new questions regarding optimal EC properties to be considered in different contexts. This study aims to investigate the influence of different locations and the effects of climate change on the definition of the optimal thermo-optical properties of an EC window, controlled by a daylighting sensor, in an office building. Six locations (Larnaca, Brindisi, Madrid, Paris, Copenhagen, Kiruna) – characterized by different latitudes and climate conditions – combined with five climate scenarios (current, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) were selected to conduct genetic optimizations considering 5-genes genomes: i) solar heat gain coefficient (SHGC) in bleached and ii) coloured state, iii) visible light transmittance (VLT) in bleached and iv) coloured state and v) thermal transmittance. The results highlight that adopting wrong EC devices in certain climates can increase the total consumption up to + 39%; instead, optimized EC systems reduce the total consumption of nearly 8% (on average), compared with traditional windows, with a peak of nearly 13% in hot climates. In particular, SHGC plays a pivotal role, with low values – in both clear and dark configurations – suggested for warm climates while higher values are optimal in cold climates. Instead, optimal thermal transmittances tend to higher values in warm cities and lower ones in colder regions. Finally, the rising temperatures in future scenarios lead to increased energy consumption – except in very cold climates – without affecting significantly the optimal EC properties