## 2 Methods
### Data Acquisition  
The outdoor measurement parameters included air temperature and solar radiation intensity, and indoor measurement parameters included air temperature and air velocity. The intensity of solar radiation was measured by a solar radiometer, and the measuring points were arranged outdoors with no shelter, as denoted by the symbol \"\(\blacksquare\)\" in Figure 3. The air temperature was measured with a thermometer and hydrometer. The measuring points of outdoor air temperature were under outdoor shades, and the measuring points of the indoor temperature were at 1.5 m above the floor in the center of the room, as denoted by the symbol \"\(\bigcirc\)\" in Figure 3. The interior wall surface temperature was measured by an enclosure heat transfer coefficient field detector, and the measuring point was located at the middle of the measured wall surface, as denoted by the symbol \"\(\blacktriangle\)\" in Figure 3. However, due to the concern that it would be inconvenient to place a hot wire anemometer in the room  
Figure 1: A typical residential building in Ningxia. Figure 2: The inside situation of the main bedroom. for a long time, the measurements of average wind speed were done by intermittent tests, and the measuring point was placed at the height of 1.0 m above the floor in the center of the room, as denoted by the symbol \"\(\oplus\)\" in Figure 3. The monitoring period for the above measuring points was 24 h, and the acquisition time interval was 10 min. The models and parameters of the instruments are listed in Table 1, and the layout of the measuring points are shown in Figure 3.  
To conduct numerical heat transfer simulations, the following material properties of the building envelope listed in Table 2 were used. In the numerical simulations, heat transfer by convection and conduction were considered. Heat transfers by radiation were studied by analyzing the heat transfer rates from the measured temperature data and the simulated results. In the convective heat transfer analysis, the convective heat transfer coefficients were affected by the temperature difference between wall and fluid. As reported by [PERSON] and [PERSON] [24], the selection of surface convective heat transfer coefficient affects the evaluation of energy consumption of buildings. In the work carried out by [PERSON] and [PERSON] [25], convective heat transfer coefficients of buildings in the range of 1-6 W/m\({}^{2}\)-K were obtained. According to a number of intermittent field tests, the average wind velocity of the indoor movement area is 0.06 m/s at maximum, far below the human body's sensory threshold to air (0.2 m/s). Therefore, the convective heat transfer coefficient was calculated using the free convection method. This was also done because the measured indoor temperature was mainly in the single figures and the mean outdoor temperature was \(-\)2.98 \({}^{\circ}\)C according to the field tests. Air properties at 0 \({}^{\circ}\)C (273 K) were used to calculate the convective heat transfer coefficient: \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Thermal Conductivity (W/m-K)** \\ \hline Solid clay brick & 0.81 \\ Mortar disasters & 0.93 \\ Glass & 1.3 \\ Door (PVC) & 0.19 \\ Air & 0.024 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thermal conductivities of materials. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Test Instrument** & **Type** & **Test Parameters** & **Range** & **Accuracy** \\ \hline Solar radiometer & JTDL-4 & Solar radiation intensity & 0-2000 W/m\({}^{2}\) & \(\pm\)0.2 \({}^{\circ}\)C \\ Thermometer and hydrometer & TESTO175-H & Air temperature & \(-\)20 to 70 \({}^{\circ}\)C & \(\pm\)0.1 \({}^{\circ}\)C \\ Envelope structure heat transfer coefficient detector & JINT-C & Interior wall surface temperature & \(-\)20 to 85 \({}^{\circ}\)C & \(\pm\)0.2 \({}^{\circ}\)C \\ Hot wire anemometer & Testo25 & Air velocity & 0–20 m/s & \(\pm\)0.03\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Models and parameters of the measuring instruments.