## 2 Materials and Methods
### Methodology for Measuring Thermal Comfort  
#### 2.1.1 Operational Internal Temperature  
The choice of ambient temperature as a thermal comfort parameter was deliberate and purposeful. Of course, thermal comfort is influenced by humidity, average ambient temperature, and air velocity. However, of these parameters, ambient temperature has the greatest influence and was the best fit for the multicriteria analysis carried out. The authors also investigated other comfort parameters, but temperature was the best fit for the methodology. The operational internal temperature was used as an indicator of thermal comfort. The analyzed building is equipped with a heating and cooling system. The operational internal temperature index, defined according to residential building quality with mechanical cooling systems, was used to determine comfort.  
The operational temperature, defined by a single parameter, represents the conditions of a homogeneous environment that physically and mathematically express the actual environmental conditions. The calculation of the operational temperature is governed by PN-EN 16798-1 [23] and EN ISO 7726 [24]. The value of the operational temperature is calculated using the following formula:  
\[\mathrm{to}=\frac{\mathrm{hcta}+\mathrm{hrtr}}{\mathrm{hc}+\mathrm{h}\mathrm{r}} \tag{1}\]  
where  
hr--heat transfer coefficient by radiation;  
hc--heat transfer coefficient by convection;  
ta--ambient temperature, \({}^{\circ}\)C;  
tr--average temperature of radiation from the partitions in the room, \({}^{\circ}\)C.  
According to EN 16798-1 'Energy performance of buildings--Ventilation for buildings--Part 1: Indoor environmental input parameters for design and assessment of energy performance of buildings with regard to indoor air quality, thermal environment, lighting, and acoustics' [23], the minimum temperature for a building equipped with heating and cooling systems can be distinguished based on the building use category, as shown in Table 2.  
The test was conducted using the temperature sensor in the sensor set shown in Figure 5. The microclimate (thermal comfort) testing device, depicted in Figure 6, records the following parameters: temperature, humidity, and air velocity (see Table 3). Based on the recorded parameters, the thermal comfort index PMV [-] and the percentage of people dissatisfied with the prevailing thermal conditions are determined. The equipment was chosen to ensure that it records the parameters relevant to the adopted research methodology, guaranteeing that the research results are consistent with the methodology.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Type of Building/Space**} & \multirow{2}{*}{**Category**} & \multicolumn{2}{c}{**Minimum Operating**} & \multicolumn{2}{c}{**Maximum Operating**} \\  & & **Temperature** [\({}^{\circ}\)C] **(1.0 clo)** & **Temperature** [\({}^{\circ}\)C] **(Summer Season) 0.5 clo** \\ \hline \multirow{4}{*}{Residential buildings (bedrooms, living rooms, kitchens), seating position, 1.2 m} & I & 21.0 & 25.5 \\  & II & 20.0 & 26.0 \\  & III & 18.0 & 27.0 \\  & IV & 16.0 & 28.0 \\ \hline \multirow{4}{*}{Offices and spaces with similar user activity (individual offices, meeting rooms, classrooms, shops, and restaurants)} & I & 21.0 & 25.5 \\  & II & 20.0 & 26.0 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Sensor data.  
Figure 5: Measurement equipment.