CFD modelling of fires in passive houses: exploring the influence of Automatic Opening Vents

In response to the growing demand for increased energy efficiency in modern constructions, the Energy Performance of Buildings Directive (EPBD 2010/31/EU) has enhanced the development of airtight dwellings. Structures that meet defined standards for annual energy demand, air changes per hour, and comfort levels can be classified as "Passive Houses". While Passive Houses offer significant benefits, their high level of airtightness introduces a potential risk of pressure build-up during fire incidents. Prior research carried out at UMONS has emphasized the necessity of Automatic Opening Vents (AOVs) in the event of a fire. These systems, essentially windows activated by a control unit, are crucial for maintaining pressure homogeneity and ensuring the safe evacuation of occupants. This thesis employs the Fire Dynamics Simulator (FDS) software to investigate the influence of AOV positioning within a case-study passive house on fire-induced pressure and mechanical ventilation system flows. Furthermore, this work compares and analyses two sub-models typically utilised to define leaks between adjacent rooms: "Pressure Zone Leakage" and "Localized Leakage". The objective is to establish general guidelines for designing and positioning an AOV, considering the presence of a mechanical ventilation system, and analysing the effect of fire exposure on tenability conditions. In the context of a fire occurrence, "tenability conditions" refer to the criteria used to evaluate the safety of people within a fire-affected environment. All these aspects contribute to the safe design of a Passive House.