## 3 Results and Discussions
### Temperatures Prediction
The temperature inside the adjacent room of DSF (T\({}_{i}\)) in the first two days without conditioning follows the variation of T\({}_{\text{cav}}\) and T\({}_{\text{e}}\) with an average value of 31.5 \({}^{\circ}\)C. Even if the exterior and the channel temperatures drop between 09:00 p.m. and 10:00 a.m., the air temperature of the interior room decreases very slowly at a minimum of 29.7 \({}^{\circ}\)C.  
Figure 11: Evolution of air temperatures and solar radiation intensity in the third period (21 th–27 th July), outdoor air curtain, natural ventilation. Figure 9: Evolution of air temperatures and solar radiation intensity in the first period (07 th–13 th July), outdoor air curtain, natural ventilation. To facilitate the heat removal from the PSF channel, in the second period of measurements (SET 2, Figure 10) forced ventilation was chosen. The results show that the temperature variation inside the channel is closely related to the exterior ones with a maximum value of 47.7 \({}^{\circ}\)C on the second day (01:00 p.m.) for an exterior temperature (T\({}_{\text{e}}\)) of 36.8 \({}^{\circ}\)C and a solar radiation intensity (I\({}_{\text{t}}\)) of 540 W/m\({}^{2}\). This shows that forced ventilation does not have a significant impact on the temperature reduction inside the channel in the overheating period of 10:00 a.m.-02:00 p.m. when the average difference between the exterior ones remains around 12 \({}^{\circ}\)C. The minimum value recorded inside the channel was 16.8 \({}^{\circ}\)C (sixth day, 6.00 a.m.) when the exterior one has the same value. Compared to the SET1, the introduction of the three ventilators in the lateral outlet of the exterior glazing facilitate the channel temperatures to reach the exterior ones rapidly for a more extended period, between 04:00 p.m. and 08:00 a.m., and a drop of the solar intensity has a quick impact on them. The average air relative humidity inside the channel is recorded to be 48.3%, and the average value of the air temperature inside the channel, T\({}_{\text{cav}}\) for the entire period is 29.0 \({}^{\circ}\)C for an exterior one of 24.9 \({}^{\circ}\)C and a wind speed of 2.2 km/h (N direction). In the third ventilation scenario (SET 3, Figure 11) of summer conditions, two openings at the top of the channel were chosen (lateral and vertical) to naturally ventilate the DSF channel. In this case, the temperature difference between the channel and the ambient reaches small values of 7-10 \({}^{\circ}\)C between 10:00 a.m.-02:00 p.m. The maximum air temperature (T\({}_{\text{cav}}\)) inside the channel reaches 44.8 \({}^{\circ}\)C on the sixth day (01:00 p.m.) for an exterior temperature (T\({}_{\text{e}}\)) of 34.9 \({}^{\circ}\)C and a solar radiation intensity (I\({}_{\text{t}}\)) of 545 W/m\({}^{2}\). The average value of the air inside the channel, T\({}_{\text{cav}}\), for the entire period is 29.08 \({}^{\circ}\)C compared with the exterior one of 26.07 \({}^{\circ}\)C with a difference of 3 \({}^{\circ}\)C, smaller than the first natural ventilation with one lateral opening, in the same weather conditions. The temperatures inside the channel and the exterior ones have almost the same value between 04:00 p.m. and 8:00 a.m. with an average difference of 1 \({}^{\circ}\)C, thus reducing the period of channel overheating. Compared to forced ventilation, the change in solar radiation intensity during the day has less impact on the temperatures of the DSF channel. The minimum value recorded inside the channel is 18.5 \({}^{\circ}\)C (3 rd day) at 6:00 a.m. when the exterior one is 17.6 \({}^{\circ}\)C. The average air relative humidity inside the channel is comparable with the previous ones for the summer season of 47.8%. A time shift of approximately one hour exists between the highest solar radiation and the maximum temperature recorded in the channel [38].