# Comparative Study of Natural Fibres to Improve Insulation in Wooden Beehives Using Sensor Networks
## 2 Materials and Methods
### Experimental Procedure  
Experiments were conducted in a controlled environment using a custom-built chamber equipped with a controllable heat source (two infrared lights of 250 W), as depicted in Figure 1. Each hive, outfitted with each type of insulation described inside its side walls and under its cover, along with a control hive without insulation (total 6 hives), were placed inside this chamber and subsequently exposed to a heating cycle (target temperature 60 \({}^{\circ}\)C; experiment duration 3 h). To ensure the robustness of our materials under extreme conditions, we conducted tests at a temperature of 60 \({}^{\circ}\)C, which is notably higher than any temperature recorded at our study site according to our collected field data. This temperature was chosen to simulate extreme stress conditions that might not typically occur but are critical for assessing the safety and effectiveness of the insulation materials under potential future climate variations. Also, the melting temperature of the wax is nearly 60-65 \({}^{\circ}\)C [34; 35]. Despite the experimental duration being 3 h, the final analysis consisted of only 1 h to achieve a common starting temperature between different materials (see Section 2.4). Between each experiment, a waiting period was established until the chamber returned to the outside temperature. The chamber's temperature was regulated by a compact temperature control system composed of an M0 microcontroller board, a digital thermometer, and a set of relays to control the heat source. This system maintained the chamber's temperature with an accuracy of \(\pm\)1 \({}^{\circ}\)C from the target temperature. Additionally, a fan system was employed to ensure uniform temperature distribution. The changes in temperature and humidity within the hive and the chamber were monitored every 30 s using the developed sensor network (refer to Section 2.3). Each insulation material was tested in three replicate experiments (total 6 \(\times\) 3 = 18 experiments).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & **Thickness** & **Density** & **Thermal** & \\  & **(mm)** & **(kg/m\({}^{3}\))** & **Conductivity** & **Reference** \\  & & & **(W/(m-k))** & **Reference** \\ \hline
**Wood fibre band** & & & & \\
**STEICO Roundtrip** & 8 & 60 & 0.038 & [30] \\ \hline
**White agglomerated cork** & 10 & 200–220 & 0.045 & [31] \\ \hline
**Black agglomerated cork** & 13 & 100–120 & 0.036–0.038 & [32] \\ \hline
**Ultracoustic R rock** & & & & \\
**mineral wool** & 8 & 32 & 0.032 & [33] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristics of the insulating materials tested.  
To further bolster the validity of our experimental results, a supplementary test was carried out. While the primary intent behind this second experiment was not to draw new conclusions, it aimed to provide additional support for our findings. We selected one of the materials to study the heat dissipation behaviour, comparing a control hive (without insulation) and a hive insulated with a black agglomerated cork. This comparison was visualised using a thermal camera. Both hives were equipped with a 250 W infrared lamp and humidity and temperature sensors, positioned identically, as shown in Figure 2. Measurements began with the ambient temperature and continued throughout a heating period of 30 min. Once the lamp was turned off, we kept recording data during the hives' 30 min cooling phase.