## 2 Materials and Methods
### Occupant Metabolic Rate (Met) and Clothing Insulation (Clo)  
Thermal comfort in indoor environments is influenced by various factors. [PERSON]'s study showed that environmental variables such as temperature, humidity, air velocity, and mean radiant temperature, as well as personal factors like activity level and clothing insulation, significantly impact thermal comfort [32]. [PERSON] et al. demonstrated that the amount of heat released from the human body (\(M\)) to the indoor environment varies depending on the body surface area and activity level, which can be calculated using Equation (1) [33]. \[M=EE\times V\dot{O}_{2}\times 1/A_{Du} \tag{1}\]  
Here, \(EE\) denotes the energetic equivalent, expressed in watt-hours per liter of oxygen (W-h/L O2), while \(V\dot{O}_{2}\) represents the oxygen consumption rate (L O2/h) and \(A_{\text{Du}}\) signifies the body surface area in square meters (m2). The metabolic rate, typically expressed in metabolic equivalents (Met), serves as a measure of occupant activity level, with 1 Met defined as the heat production per unit area of a subject under resting conditions and in thermal equilibrium, equivalent to 58 W/m2 [34]. Considering the specific characteristics of residential buildings, the activities of occupants within the measurement space and their corresponding MET values can be defined as delineated in Table 3 by reconfigured from [35,36]. Clothing serves a crucial role beyond simply covering the body; it acts as a barrier that regulates heat exchange between the human body and the external environment. The \"Clo value,\" a measure of clothing's thermal insulation, significantly influences human thermal comfort [37]. The value varies depending on factors such as the type of clothing, its thickness, and the number of layers worn [38]. It can be determined through practical measurements or calculations. In thermal comfort assessments, the Clo value typically refers to the whole-body thermal resistance, indicating the overall thermal resistance of the human body. Relevant standards, such as those set by ISO [35] and ASHRAE [36], recommend a Clo value of 0.5 for summer clothing and 1.0 for winter clothing. However, these values are based on general activities, and during sleep, when individuals are covered by bedding, the Clo value can increase substantially. Given that humans spend a significant portion of their day sleeping, the additional insulation provided by bedding during sleep can dramatically increase the overall Clo value. Previous studies have shown that the Clo value during sleep can range from 2.0 to \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Description**} \\ \hline Type & 24 G millimeter wave radar series \\ Operating frequency band & 24–24.25 GHz \\ Power supply & DC 5 V, over 200 mA \\ Module method & Frequency Modulated Continuous Wave \\ Data interface & Universal asynchronous receiver/transmitter \\ Maximum sensing area & Three spatial zone detection and tracking \\ Distance & Maximum 6 m \\ Angle & \(\pm\)60\({}^{\circ}\) \\ Data rate & 10 Hz \\ Operating temperature & \(-\)40–85 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Occupant detection sensor specifications. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Activity** & **Met** & **Heat Production (W/m2)** \\ \hline Sleeping & 0.7 & 40.6 \\ Reclining & 0.8 & 46.4 \\ Standing & 1.4 & 81.2 \\ Sitting with Typing & 1.2 & 69.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Heat production by occupant’s potential activities in the target room. 4.0 or more when using typical bedding conditions [39]. This indicates that individuals are in a much more thermally insulated state during sleep compared to when they are awake. Such elevated Clo values during sleep can influence indoor thermal environments and subsequently affect heating energy consumption. In this study, we adopted differentiated Clo values during conventional activities and during sleep (refer to Table 3) to account for the varying thermal conditions.