The need for sustainability and a smaller ecological footprint lead to the construction of more airtight building envelopes with better thermal insulation to increase energy efficiency according to the Energy Performance of Buildings Directive (EPBD 2010/31/EU). However, specific fire risks can be encountered by the occupants since they can be blocked for a long period due to the fire-induced pressure increase and the inward door opening. In a previous experimental campaign, wood crib fire

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... were carried out for measuring fire-induced pressure in a 70m3 airtight building. High pressure inside the rooms was observed highlighting the problems for the evacuation of the occupants. Moreover, these experimental results were also used to validate the Fire Dynamics Simulator (FDS). Satisfactory predictive capability of FDS was obtained for fire-induced pressure and mechanical ventilation considering the influence of the pressure on the area of the leakages but the heat release rate (HRR) was fixed as input data for the simulations. Computational Fluid Mechanics CFD modeling is regularly used in fire safety engineering but generally, a significant limitation comes from the HRR which has to be imposed as input data. This paper presents an evaluation of FDS v6.7.6 capability to predict fire-induced pressure without setting the HRR as input data. Fire tests were carried out with a simple fuel load such as heptane pool fire. At first, heptane pool fires were performed in an open atmosphere for preventing complex interactions between the compartment and fuel vaporization rates and evaluating the ability of FDS to predict liquid pool fire fuel mass-loss rates. Secondly, twenty-one heptane pool fires were performed in a 70 m3 setup for evaluating the capability of FDS to predict heptane mass-loss rates, fire-induced pressure, and temperature field in the fire room in several enclosure configurations.