## 2 Materials and Methods
### Computer Simulation
#### 2.3.3 Simulation Case Design: Winter Heating Case/Summer Mixed Cooling Case  
Because the active system used for both cooling during summer and heating during winter for the internal spaces is AC in southern China, the electricity from the power grid was chosen as the energy supply pattern in the simulation throughout the year. The setting parameters in the simulation need to be adjusted considering the air-conditioned conditions and occupancy schedules for various rooms.  
In this study, the energy performance of five buildings (CASE-A/CASE-B/CASE-C/CASE-D/CASE-E) was investigated as a function of two operational cases. In the winter heating case, the building was airtight, and air exchange between the inside and outside occurred solely via infiltration. The inside air temperature was controlled using a heating system (18 \({}^{\circ}\)C in this study). In the summer mixed cooling case, the buildings  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Component** & **Layers** & **Thickness (mm)** & **Thermal Conductivity (W/(m-K))** & **Density (kg/m\({}^{3}\))** & **Specific Heat (J/kg\(\cdot\)K)** & **Heat Transfer Coefficient (W/(m\({}^{2}\cdot\)K))** \\ \hline CASE-A roof & Reinforced concrete & 120 & 1.74 & 2500 & 920 & \\ \hline CASE-A external wall & 240 clay brick & 240 & 0.81 & 1800 & 1050 & \\ \hline CASE-A internal wall &
\begin{tabular}{c} 120 clay brick \\ \end{tabular} & 120 & 0.81 & 1800 & 1050 & \\ \hline CASE-A floor & Reinforced concrete & 100 & 1.74 & 2500 & 920 & \\ \hline CASE-A windows & Single clear 6 mm & 6 & & & 6.4 \\ \hline CASE-C insulation roof & XPS & 10–100 & 0.03 & 27 & & \\ \hline CASE-C insulation wall & XPS & 10–100 & 0.03 & 27 & & \\ \hline CASE-E double single-glazed windows & & & & & 3.0 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Material descriptions of the tubular house model.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Zone Properties** & **Description** \\ \hline Zone number & 6 \\ \hline The type of active or passive system used & \
\begin{tabular}{c} Electric heating coil system (in winter) \\ Natural ventilation (in summer, when 12 \({}^{\circ}\)C \(<\) T outdoor \(<\) T inside) \\ DX cooling coil system (in summer) \\ \end{tabular} \\ \hline Comfort lower band & 18 \({}^{\circ}\)C \\ \hline Comfort upper band & 26 \({}^{\circ}\)C \\ \hline Occupants’ metabolic rate &
\begin{tabular}{c} Sedentary activity: 70 W (6 persons) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Zone properties of the tubular house model.  
were operated in a mixed mode of active cooling and natural ventilation. More specifically, if the outside air temperature was lower than the inside temperature and higher than the natural ventilation set-point temperature (12 \({}^{\circ}\)C in this study), then natural ventilation was introduced to chill the indoor air. If the cooling capacity of the natural ventilation is insufficient, the active cooling system operates to maintain the indoor air set-point temperature (26 \({}^{\circ}\)C in this study).  
The energy consumed by the system was in the form of electricity, and the COP of the cooling system was 1.67. The internal gains (including lighting and equipment) were designed to be 4 and 5 W/m\({}^{2}\). All interior spaces were heated or cooled, except for the yards.  
According to a questionnaire survey of 121 households, there were six members in most families. Considering daily life and sleep habits, indoor occupancy reaches its maximum during mealtimes, at 7:00-8:00 a.m., 1:00-2:00 p.m., and 5:00-6:00 p.m. Outside of these times, an average low occupancy of two persons is typical. The sensible heat was quantified at 70 W for each person with light activity.