Energy performance of novel low-cost inkjet-printed electrochromic glazing

Rising temperatures are leading to an increase in the cooling demand of buildings. Electrochromic (EC) glazing can be a promising solution for controlling solar heat gains while maintaining outdoor views. This paper presents the results of the monitoring of prototype panels of a novel type of inkjet-printed EC glass under real use and weather conditions in a small office building in the Netherlands. This building contained two identical west-facing meeting rooms of which one was equipped with EC triple glass IGUs and the other with normal triple glass IGUs. Each room was equipped with local heating/cooling units of which the energy use was monitored, and with an extensive environmental sensor network. Sensor and calendar data was fed into an energy balance model for each of the rooms for the entire measurement period, allowing to correct for differences between the two rooms with respect to heat losses and gains and use conditions. The results of the monitoring showed that in the meeting room with EC glass IGUs, the heating demand increased by 34% in Jan.-Mar. 2024 while in Sept. 2023 the cooling demand decreased by 3%. The main reason for the increase in heating demand was found to be the lower g-value of the EC glass IGUs in clear state as compared to the normal IGUs. The almost similar cooling demand was a result of a trade-off between the lower direct solar transmittance of the EC glass IGUs and the heating up of the absorptive layer inside the IGUs. Furthermore, an experiment with participants showed that in general in dark state, satisfaction with view clarity, daylight colour and daylight availability was higher for the EC glass IGUs. In transparent state, no significant difference was perceived between the EC glass IGUs and standard IGUs, except for view clarity.