## 3 Results and Discussion
### Thermal Performance of the Insulating Envelope and Energy Simulation
#### 3.4.2 Energy Simulation Results  
To evaluate the energy efficiency of different insulation materials, a simulation was conducted considering three different scenarios. The first scenario incorporated rice husk fiber insulation (A), the second scenario utilized recycled polyurethane insulation, and the third scenario represented the non-insulated case, serving as a baseline to assess the impact of insulation on energy consumption (Figure 18). Figure 16: Surface temperature of (**A**) rice husk and (**B**) recycled PUR during the day. Figure 17: Temperature profiles of (**A**) rice husk and (**B**) recycled PUR during the day. Figure 18: Different scenarios simulated. (**A**) Rice husk fiber, (**B**) recycled PUR, (**C**) non-insulated. Temperature Homogeneity  
The results presented in Figure 19 indicate that rice husk fiber maintains indoor temperatures within the comfort range throughout the year, demonstrating its effectiveness in stabilizing indoor thermal conditions and its provision of superior thermal regulation compared to the other scenarios. Recycled PUR insulation performs better than the non-insulated scenario by reducing temperature fluctuations; however, it is still below the lower comfort zone [55] during winter, indicating that while it offers some insulation, it is not as effective as a rice husk fiber. The non-insulated scenario exhibits the highest temperature variations, closely following outdoor temperatures, which indicates the importance of using insulation materials to enhance indoor thermal stability and energy efficiency. Additionally, rice husk fiber insulation shows the best performance in extreme temperature conditions, preventing excessive heat loss in winter and minimizing overheating in summer, making it a viable and sustainable option for energy-efficient construction climates like Temuco. The rice husk within the modular system achieves thermal comfort levels comparable to dwellings that comply with the technical buildings code standard [26]. Overall, these findings suggest that the rice husk fiber is a highly effective natural insulation material, confirming its potential application in sustainable building systems for enhanced thermal efficiency and occupant comfort. The results presented in Figure 20 illustrate the energy consumption in kWh required for heating and cooling the modular unit under different insulation scenarios. The data clearly indicate that the rice husk fiber exhibits the lowest energy consumption, outperforming both recycled PUR and the non-insulated case. The non-insulated scenario shows significantly higher energy demand, particularly during the winter months, where heating consumption peaks at well above 643 kWh. This highlights the inefficiency of an uninsulated module at maintaining indoor thermal stability, requiring excessive energy to compensate for heat loss. The rice husk fiber demonstrates the highest energy efficiency. In Table 4, the annual consumption and the rice husk scenario that maintains lower heating and cooling demand compared to the other two scenarios is shown, with 9.56 kWh/m\({}^{2}\)-year of heating demand, which is close to the 11.70 kWh/m\({}^{2}\)-year reported by [25] in a similar construction using wheat straw insulation. The heating energy demand observed using rice husk fibers is significantly lower compared to other thermally improved dwellings in Temuco, with a range between 40 and 80 kWh/m\({}^{2}\)-year [26]. This represents an approximate reduction of 81%, underscoring rice husk fiber's substantial potential for enhancing energy efficiency in buildings. Figure 19: Annual indoor temperature profiles for rice husk, recycled PUR, and no insulation scenarios. This confirms its superior thermal performance, reducing the need for mechanical heating in winter and cooling in summer. The results suggest that rice husk fiber not only improves indoor comfort but also enhances energy efficiency, making it a more sustainable and effective alternative for insulation in modular construction systems.