###### Abstract  
Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements' dimensions, burner heat release rate variation) were imposed to the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model. Besides the air temperature, at this point, other essential parameters were determined in the entire experimental space: indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. We found that if the ventilation rate increases, the indoor temperatures in that specific point decrease, and the sprinkler is activated later or, in some cases, it might never be activated. However, this conclusion is not valid for the entire analyzed space, as the ventilation system alongside the natural air movement imposes specific air speed and specific temperature distribution inside the analyzed space. m 2021 11  
We presented these statistics to underline that fire protection is one of the most important aspects during the early stage of a building design. The smoke-controlled ventilation and sprinklers represent two of the main active systems for fire protection that should be carefully analyzed during the building design stage. The main aim of smoke-control ventilation is to extract hot and toxic gas out of the building that caught fire, in order to allow occupants to evacuate the enclosure before untenable conditions are reached. The purpose of a sprinkler system is to control, contain, and extinguish a fire, as well as to prevent the smoke from being generated. Hot smoke and toxic gases, however, are responsible for more deaths in fires than direct exposure to flames. In order to ensure human fire protection, the correct design of these systems is of the upmost importance, and it should fire modeling take into account as an important part of building design. There are currently three main categories of methods for modelling the reaction to fire of buildings [4]:  
* simplified mathematical models for the description of the evolution of certain parameters describing the fires, such as the temperature-time logarithmic curve in EN 1991-1-2 [4];
* zonal models who divide the burnt space into two zones, each zone being characterized by an average temperature: the warmer upper zone and the colder lower zone [5;6]; and
* computational fluid dynamics (CFD) models that allow the simulation of the fire closer to the reality. CFD models are based on the finite volumes numerical method, involving the division of the model space into a fine grid of three-dimensional cells. For each cell, the physical and chemical parameters are known at a given time, by solving a particular form of the Navier--Stokes equations [7; 8; 9]. The concern for the fire safety of buildings, as an engineering science, is relatively new, and it is developed in two main directions: experimental and numerical studies (or a combination of the two). The purpose is to understand fire evolution and find solutions to increase the safety of buildings under the probable action of fire. In the early phases of the research, experimental studies were predominantly used in the absence of high-performance computers, which would have made it possible to use CFD methods. For example, [PERSON] et al. [10] conducted several experiments at the real scale of a building by setting an apartment on fire.