Scrutinizing modeling and analysis methods for evaluating overheating risks in passive houses

In response to the increasing demand for energy efficient houses, passive houses are quickly becoming a required standard for new buildings. Despite their energy efficiency, the occupants have reported thermal discomfort during the summer. This study investigates the effects of choices made in the process of evaluating overheating risks in passive houses. Key questions raised in this study relate to the effects of different thermal comfort criteria, the relevance of the building's energy model to represent airflow phenomena, and the role of uncertainty associated with simulation models utilized for the analysis. The overheating assessment results were observed to be highly dependent on thermal comfort criterion choices, and the energy model was found to undervalue the overheating hours by 33.33% due to design infiltration and ventilation rate overestimation. This result highlighted the necessity of properly modeling airflow phenomena by coupling the thermal and airflow network models for overheating analysis. The sensitivity analysis results indicated that although most of the dominant uncertain parameters are included in the thermal model, when analyzing the output variance caused by the uncertainty related to each modeling method, both the thermal (82.5%) and airflow network (17.5%) models showed a significant variance in the number of overheating hours.