## 3 Results
### The Summary of Experimental Results for Different Seasons  
In order to confirm the validity of the results, Table 3 shows the summary of the average values for exterior conditions (ambient temperature, solar radiation intensity, relative air humidity, and wind velocity) and interior conditions (interior temperature, relative air humidity, and average air velocity). The interior temperatures are presented as ranges. The maximum temperatures (22-26) \({}^{\circ}\)C were detected for summer, but the hottest days have temperatures during the evaluated time period about 32 \({}^{\circ}\)C. The temperature minimum (0-12) \({}^{\circ}\)C was obtained for the winter season. Since the temperature values in the exterior and interior are directly related to the intensity of solar radiation, a correlation analysis was performed. The correlation between indoor and outdoor temperature is expressed by a correlation coefficient of 0.928 and the correlation between the intensity of solar radiation and indoor temperature by a coefficient of 0.958 during the model day in autumn (Figure 13). The graphical relations for solar radiation intensity in sunny, cloudy, and model day are presented in the Figure 14.  
Overview of the solar radiation intensity values for different seasons is presented in Table 3. There is evidence that solar radiation intensity varies from 0.71 kWh\(\cdot\)m\({}^{-2}\) in the winter season to 3.15 kWh\(\cdot\)m\({}^{-2}\) during the summer. From summary results, it is clear that the intensity of solar radiation has a direct influence on the exterior temperature. The values of the wind velocity values change depending on the season from 1.4 m\(\cdot\)s\({}^{-1}\) in spring to 0.9 m\(\cdot\)s\({}^{-1}\) in autumn. There was no detected correlation between the exterior wind velocity and average air velocity in the interior due to the usage of the ventilation system in the interior. The air velocity in the real cowshed was on average 0.2 m\(\cdot\)s\({}^{-1}\) during \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Exterior Conditions**} \\ \hline
**Average Values** & **Spring** & **Summer** & **Autumn** & **Winter** \\ \hline Ambient temperature (\({}^{\circ}\)C) & 8.8 & 23.9 & 12.2 & 1.4 \\ Solar radiation intensity (kWh\(\cdot\)m\({}^{-2}\)) & 2.15 & 3.15 & 1.26 & 0.71 \\ Relative humidity (\%) & 66.7 & 64.0 & 76.3 & 78.7 \\ Wind velocity (m\(\cdot\)s\({}^{-1}\)) & 1.4 & 1.0 & 0.9 & 1.2 \\ \hline \multicolumn{5}{c}{**Interior Conditions**} \\ \hline
**Average Values** & **Spring** & **Summer** & **Autumn** & **Winter** \\ \hline Interior temperature (\({}^{\circ}\)C) & 12–19 & 22–26 & 11–18 & 0–12 \\ Relative humidity (\%) & 46–63 & 35–55 & 40–65 & 45–78 \\ Average air velocity (m\(\cdot\)s\({}^{-1}\)) & 0.22 & 0.90 & 0.22 & 0.22 \\ Average THI without PV system (-) & 59.35 & 69.90 & 58.03 & 45.97 \\ Average THI with PV system (-) & 58.31 & 66.90 & 57.05 & 46.48 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The summary of external and internal conditions in context of Temperature—Humidity—Index (THI). the spring, autumn, and winter, but in summer the air velocity reached a maximum value 0.9 m\(\cdot\)s\({}^{-1}\) due to the increased demand for the interior cooling. Relative humidity was measured in the exterior and interior. The exterior humidity varies from 64.0% to 78.7%. The highest difference between the exterior and interior relative humidity was 19%. Figure 15 displays relations for ambient temperature and relative humidity during the year. There was no confirmed correlation between mentioned parameters because of a very small correlation coefficient, \(-0.618\). The interesting results were identified during the model day in October presented in Figure 16. The correlation coefficient for relations between the exterior and interior relative humidity dependencies was near 1.