## 6 Conclusions  
The generality of the presented results always depends on the variation of different parameters. In this study, we focused only on the variation of the temperature in a specific point in space, close to the sprinkler position. We must clearly point out that our study was not intended to obtain a general conclusion but to allow for the validation of a verified protocol that can be used for the further construction of more complex models. During this research, the influence of mechanical ventilation on the survival conditions of the users of a building was analyzed. This was achieved by observing four parameters: indoor temperature, visibility, oxygen concentration, and carbon dioxide concentration. The real phenomena, in such an environment, and corresponding modelling allow for the observation of these inside the considered space. However, the purpose of our study was to understand the relationship between two active systems for fire protection: the ventilation and sprinkler systems, i.e., how the operation of one system could influence the efficiency of the other system. These two systems influence one another by means of the air temperature around the sprinkler position. This is why we chose the calibration parameter to be the temperature in a point located close to the sprinkler position. The current paper  
Figure 13: Influence of ventilation on survival conditions; **(a)** oxygen concentration and **(b)** carbon dioxide concentration distribution on longitudinal plane (Y = 2.10 m), at time step 300 s.  
presents the first step of a larger approach involving the evolution of the above-mentioned parameters, and this first step was the experimental and CFD modelling, focused on the two systems influence. We have also to point out that, in our quest dedicated to obtaining accurate models to be used in fire safety engineering, we did not find literature studies that evidenced the influence of the two types of active protection systems. In the present study, three distinctive cases were analyzed: CALIB1- no air extraction, CALIB2- average exhaust speed at the outlet of 1.0 m/s, CALIB3- average exhaust speed at the outlet of 4.5 m/s. By comparing the three situations, the following conclusions can be drawn:  
* If the ventilation rate increases, then the indoor temperatures decreases. For the first two cases (CALIB1, CALIB2), up to t = 155 s temperatures go higher than 60 \({}^{\circ}\)C and no longer fall below this value. In the case of good ventilation (CALIB3), throughout the analysis period, the temperature does not exceed this value, the conditions being specific to survival (it has the disadvantage that it would not have triggered the sprinklers, if they had existed). * If the ventilation rate increases, then the visibility increases. In case of poor ventilation (CALIB1, CALIB2), the visibility is maintained above 10 m, for a maximum of 35 s, after which it decreases below 2 m until the end of the study. In case of good ventilation (CALIB3), the visibility is maintained above 10 m to 125 s but remains above 5 m until the end of the study. * If the ventilation rate increases, then the O\({}_{2}\) concentration increases. In all cases, the values remain within reasonable limits, but a decrease in oxygen concentration of 9.6% is identified for CALIB1, 6.2% for CALIB2, and only 1.9% for CALIB3. * If the ventilation rate increases, then the CO\({}_{2}\) concentration decreases. In all three cases, the values remain within reasonable limits, but an increase in the concentration with carbon dioxide up to 1.1% is identified for CALIB1, 0.7% for CALIB2, and only 0.2% for CALIB3 (4.7-times higher than CALIB1). Other studies, regarding the effect of the ventilation upon the temperature indoors, concluded that the ventilation has a small influence [23], while in our study we concluded (both experimentally and numerically) that the temperature varies considerably, due to the ventilation rate (see Figures 9 and 11). Further, the ventilation has the potential to influence the activation of the sprinkler system.