The work during the second reporting period from month 19 to 30 addressed the technology optimization for both electrochromic and thermochromic systems. The modulation of the visual light transmittance could be further improved reaching 78% to 7% with a hybrid electrochromic cell combining tungsten oxide and prussian blue. As the first initiative worldwide, Switch2Save could successfully demonstrate thermochromic thin glass rolls with > 4 m length and 0.3 m width. The thermochromic switching temperature was 21°C, the visual light transmittance was 48%.
Another key activity in the second reporting period was the preparation of technology demonstration in two operational buildings, one at NIKAIA Hospital in Greece and one office building in Uppsala, Sweden. The activities included the verification of all manufacturing steps for large smart electrochromic insulating glass units (manufacturing a 4.4 m² large demonstrator), the development of suited control units for electrochromic switching, component level performance and durability testing and finally the pre-installation monitoring of energy demand in the demonstrator buildings. Both a fully wireless smart control unit (Samsung SmartThings compatible) and a WIFI capable low power control unit were developed for manual and automatic switching of EC windows. Manufacturing of more than 200 m² electrochromic films and smart insulating glass units is currently ongoing. Quantified test protocols for photometric assessment, thermal and lighting comfort assessment have been developed. The durability test protocols for electrochromic systems, that were derived in the first reporting period, are currently being applied to electrochromic test IGUs to verify their durability for up to 25 years of use in application.
