## 3 Materials and Methods
### Simulation Setup and Data Analysis
\begin{array}{rcl}Men&\rightarrow&A_{D}=0.607l+0.0127m-0.0698&[{\rm m}^{2 }]\\ Women&\rightarrow&A_{D}=0.589l+0.0126m-0.0461&[{\rm m}^{2}]\end{array}  \tag{3}\]  
Heat loss through the skin is divided into the loss to the environment and the loss to the mattress, calculated through simple conduction, considering the thermal conductivity (k) and thickness (d) of the mattress (Equation (4)). Heat loss through skin diffusion (E\({}_{d}\)) is characterized by Equation (5). \[E_{cond}=\alpha\ k\ \frac{t_{sk1}-t_{b}}{d}\qquad\left[{\rm W}/{\rm m}^{2}\right] \tag{4}\]  
\[E_{d}=3.074\cdot 10^{-3}\ (1-0.8\alpha)(p_{skin1}-p_{a})\qquad\left[{\rm W}/{ \rm m}^{2}\right] \tag{5}\]  
where P\({}_{\rm skin1}\) is the saturated vapor pressure at the average skin temperature of body parts not in contact with the bed. Additionally, heat loss through convection and radiation is calculated using Equation (6). \[E_{C+R}=(1-\alpha)\ \frac{t_{skin1}-t_{o}}{R_{cl}+\frac{1}{f_{cl}\ (h_{r}+h_{c})}} \tag{6}\]  
where t\({}_{\rm skin1}\) is the average skin temperature; t\({}_{0}\) is the operative temperature; h\({}_{c}\) is the convection heat transfer coefficient; h\({}_{r}\) is the radiation heat transfer coefficient; f\({}_{cl}\) is the clothing coverage factor; and R\({}_{cl}\) is the thermal resistance of the bedding. For a person laying down, h\({}_{r}\) is approximately 3.235 W/m\({}^{2}\)K, and h\({}_{c}\) is calculated as  
\[h_{c}=0.881\ |t_{skin1}-t_{a}|^{0.368}\qquad\left[{\rm W}/{\rm m}^{2}{\rm K}\right] \tag{7}\]  
Therefore, using all the aforementioned equations, the equation for \(L\) can be determined as  
\[L=40-\frac{13.41-1.519\cdot 10^{-3}p_{a}-0.13\ t_{a}}{A_{D}}-\left(3.074\cdot 10^{ -3}\ (1-\alpha)(p_{skin1}-p_{a})+(1-\alpha)\ \frac{t_{skin1}-t_{o}}{R_{cl}+\frac{1}{f_{cl}\ (h_{r}+h_{c})}}+\alpha\ k\ \frac{t_{skin2}-t_{a}}{d}\ \right) \tag{8}\]  
For this study, the following specific conditions were established:  
* All women were assumed to have a height of 1.6 m and a weight of 60 kg. * The latex mattress had a thermal conductivity of 0.048 W/mK and a thickness of 0.20 m.
* The heat generated by the users (\(M\)) was estimated at 0.7 met, which is characteristic of sleeping individuals [49]. * Following the application by [PERSON] et al. [48], P\({}_{\rm skin1}\) was set to 5520 Pa, t\({}_{\rm skin1}\) to 34.6 \({}^{\circ}\)C and t\({}_{\rm skin2}\) to 35.4 \({}^{\circ}\)C.  
Once \(L\) was characterized, the PMV was obtained (Equation (9)). According to EN 16798-1 [50], thermal comfort ranges between \(-0.7\) and 0.7 PMV were considered, with each nighttime hour in July and August (23:00 to 8:59) analyzed. Relevant studies from the largest global thermal comfort database suggest that there is no significant difference when the PMV falls between \(-1.0\) to \(1.0\)[51]. Thus, an alternative scenario for replicability in other schools could involve adopting or assuming the range from \(-1.0\) to \(1.0\) as being comfortable and calculating another proposal for comfort hours, as demonstrated by [PERSON] et al. [52] using their assessment index. \[PMV=\left(0.303\;e^{-0.036M}+0.028\right)L \tag{9}\]  
Daytime thermal comfort was also evaluated. It was assessed using the European thermal comfort standard. Both ASHRAE 55-2017 and EN 16798-1:2019 serve as international standards for adaptive thermal comfort through natural ventilation. These standards rely on variations in the outdoor air temperature (t\({}_{\text{pma(out)}}\)), which is a weighted average of daily outdoor temperatures (T\({}_{\text{out,d}}\)), with a coefficient of 0.6 for mid-latitude climates. When t\({}_{\text{pma(out)}}\) falls within a specific range, the indoor temperature adjusts naturally; otherwise, heating or cooling systems are required. The EN 16798-1:2019, widely used in Europe, classifies buildings into three categories: (i) category I (special buildings such as hospitals); (ii) category II (new buildings); and (iii) category III (existing buildings).