## 4 Discussion of the Results
### Effect of Cross-Ventilation on Thermal Behaviour  
As illustrated in Figure 23, prior to the initial ventilation period, the indoor temperature was approximately 34 \({}^{\circ}\)C, while the outdoor temperature ranged between 35 \({}^{\circ}\)C and 20 \({}^{\circ}\)C. However, the implementation of night ventilation resulted in a reduction in the indoor air temperature below 30 \({}^{\circ}\)C during the night time hours, with a daytime temperature of approximately 32 \({}^{\circ}\)C. In other words, the effect of night time cross-ventilation results in a passive reduction in the air temperature in the ancient building by approximately 4 \({}^{\circ}\)C,even when the outside temperature is higher. This same effect can be observed on the other experimental days. It can be seen that in period six, due to the reduction in the outdoor air temperature, the indoor room temperature is reduced to around 25 \({}^{\circ}\)C, compared to 34 \({}^{\circ}\)C measured on the previous days. This highlights the cooling potential, which, although not high, allows the air temperature to be reduced by several degrees.  
The utilization of the calibrated thermal model facilitates the estimation of the cooling potential on days with cross-ventilation in comparison to the temperature that would have been obtained in the absence of such ventilation (Figure 23). During the nocturnal period, the indoor air temperature can be reduced in 2 \({}^{\circ}\)C on the initial day and between 4 \({}^{\circ}\)C and 6 \({}^{\circ}\)C on the third night. This results in an anticipated indoor air temperature of approximately 33 \({}^{\circ}\)C during both night and day in the initial section. However, due to the non-invasive technology employed in the historic building, temperatures between 29 \({}^{\circ}\)C and 31.5 \({}^{\circ}\)C are achieved with only two days of passive operation.  
If this simulation is performed for 20 consecutive nights of night time cross-ventilation, the results are very interesting. The maximum temperature difference between the temperature with and without cross-ventilation was 6 \({}^{\circ}\)C, with an average over the 20 days of cross-ventilation of 3.8 \({}^{\circ}\)C. On the initial day of night time cross-ventilation, the temperature differential is 1.3 \({}^{\circ}\)C. However, from the second night onwards, the difference increases to 2.7 \({}^{\circ}\)C until reaching the aforementioned maximum. During the 5 days after the cessation of cross-ventilation, the indoor temperatures still maintain significant differences of more than 1 \({}^{\circ}\)C. During the following 5 days, the difference decreases, but is still perceptible with differences greater than 0.5 \({}^{\circ}\)C. After these 10 days, the temperature difference is between 0.2 \({}^{\circ}\)C and 0.5 \({}^{\circ}\)C, being very small, until 20 days after the end of cross-ventilation, both temperatures are practically the same. It is therefore evident that the effect of cross-ventilation in reducing indoor temperatures is emphasised, not only during its implementation, but also in the following days, thanks to the architecture of the ancient building. The usefulness of cross-ventilation as a passive cooling strategy in hot climates is highlighted, providing an immediate benefit and a residual effect that, although decreasing, contributes to improving thermal comfort in the short term.