Heat, air and moisture (HAM) models allow efficient simulation of the building components’ hygrothermal behavior. However, specific model assumptions, simplifications and approximations, as well as users’ preferences, biases and mistakes in the implementation of material properties, boundary conditions, etc., may yield divergences among results from different models. The lack of a standard framework for HAM model quality assessment results in inconsistent benchmark cases and assessment methods in previous studies. Thus, this state-of-the-art empirical round robin validation targets to test the robustness and the reliability of HAM models in predicting one-dimensional hygrothermal responses of building components under controlled boundary conditions. It ran from 2023 to 2024, was coordinated by KU Leuven, and achieved participation of 38 groups from 19 countries. A comprehensive experimental dataset serves as the “correct answer”, and simulation results from other participants form “reference answers”. Since the boundary conditions are simple and explicit, the material properties’ implementation has the main impact on the simulated hygrothermal responses. Most models prove to be robust, particularly in the heat transfer prediction. The moisture transfer prediction, on the other hand, looks more challenging. Reliability is also achieved by most models, as the deviations between simulation and experimental results are reduced when actual measured material properties are implemented as inputs. However, inappropriate and/or incorrect implementations are also observed. More in-depth investigations are performed for a better understanding of HAM-simulation tools and achieving their better performance in predicting and interpreting the hygrothermal behavior of building components. ... Read more

Rising temperatures are leading to an increase in cooling energy demand and thermal discomfort due to overheating. Despite dynamic switchable glazing being a promising solution for controlling solar radiation while preserving user access to outdoor views, their cost is currently a barrier to their widespread adoption. The recent development of low-cost inkjet-printed switchable glazing offers a cost-effective alternative; however, its performance remains uncertain concerning its contributions to energy efficiency and user satisfaction in terms of thermal comfort and visual experience. This study presents a multi-domain evaluation of the performance of a novel low-cost inkjet-printed glazing with users in terms of their satisfaction with the environment, personal control and interaction. In comparison to a conventional façade with static glazing and external roller blinds, the EC glazing performed better than the conventional façade if the shading is fully down. In this case, higher satisfaction was measured in terms of view clarity, daylight access and colour in the room with the EC glazing. When comparing the performance of the EC glazing at the clearest state with conventional glazing with blinds raised, users’ satisfaction was not significantly different, except for the satisfaction with view clarity. Despite the long transition time of the EC glazing, users were not significantly dissatisfied with the speed of transition. Overall, these preliminary results show that this novel EC glazing is well-accepted by users especially as an alternative to traditional dark roller blinds, but further research is required to investigate its performance during summer. ... Read more

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. ... Read more