Periodic Reporting for period 2 - Switch2save (Lightweight switchable smart solutions for energy saving large windows and glass façades)
Período documentado: 2021-04-01 hasta 2022-03-31
In modern architecture, large-area glazing is a continuing trend because of its appearance and design variety. Large southwards-oriented windows help to reduce the energy demand for heating in winter. However, large-area glazing may significantly increase the energy demand for cooling and air-conditioning in hot summers. Smart Glass Solutions – such as electrochromic (EC) and thermochromic (TC) windows and glass façades –control the radiation energy transfer with the “touch of a button” and thus can drastically reduce the energy demands for heating and air conditioning of large buildings. In addition, they allow superior indoor lighting comfort in contrast to conventional mechanical window blinds. On 1st October 2019, the EU-funded initiative “Switch2save” was launched to improve the availability and affordability of EC and TC smart glass technologies. Switch2Save thereby aims at integrating both EC and TC films as lightweight components to insulating glass units that can be used for large area windows and glass facades. Based on such smart windows, Switch2Save will demonstrate the energy saving potential of smart glass solutions in two fully-operational buildings - an office building in Uppsala, Sweden and the 2nd largest hospital in in Greece, in Athens.
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 electochromic systems, that were derived in the first reporting period, are currently being applied to electochromic test IGUs to verify their durability for up to 25 years of use in application.
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 electochromic systems, that were derived in the first reporting period, are currently being applied to electochromic test IGUs to verify their durability for up to 25 years of use in application.
The Switch2Save project's progress beyond the start of the art is based on the superposition of electrochromic (EC) films and thermochromic (TC) thin glass that are both integrated into the same insulating glass unit (IGU) as base component for windows and glass facades. With less than 0.6 kg/m² specific weight (<2% of the total IGU weight), EC and TC modules can be integrated without any additional requirements to building structure. The manufacturing processes for both the electrochromic and the thermochromic films are optimized to potentially reduce industrial manufacturing cost of the component by more than 25 % compared to today's state of the art.
Specially adapted system designs and automatic switching protocols for the electrochromic film maximize the energy saving potential in the building: Modelling results demonstrated that Switch2Save EC and TC technology may reduce HVAC (heating, venting, air conditioning) energy demand for buildings with large windows or glass facades by up to 70%. Majorly, the saving is determined by a drastical reduction of the energy demand for cooling on hot summer days. The Switch2Save lightweight energy smart IGU are suitable both for renovating existing buildings (by replacing old windows) and for construction of new buildings. The windows synergize well with any solution for energy smart non-transparent wall and facade components to further decrease energy demand of buildings towards zero and plus energy houses. Electrochromic windows enable significantly more comfortable indoor lighting conditions compared to mechanical window blinds. Such mechanical windows blinds can be left out completely - which saves overall installation cost and reduces complexity of the building structure for large glass facades.
Specially adapted system designs and automatic switching protocols for the electrochromic film maximize the energy saving potential in the building: Modelling results demonstrated that Switch2Save EC and TC technology may reduce HVAC (heating, venting, air conditioning) energy demand for buildings with large windows or glass facades by up to 70%. Majorly, the saving is determined by a drastical reduction of the energy demand for cooling on hot summer days. The Switch2Save lightweight energy smart IGU are suitable both for renovating existing buildings (by replacing old windows) and for construction of new buildings. The windows synergize well with any solution for energy smart non-transparent wall and facade components to further decrease energy demand of buildings towards zero and plus energy houses. Electrochromic windows enable significantly more comfortable indoor lighting conditions compared to mechanical window blinds. Such mechanical windows blinds can be left out completely - which saves overall installation cost and reduces complexity of the building structure for large glass facades.