Development and Validation of a Low-Cost Arduino-Based Lee Disc System for Thermal Conductivity Analysis of Sustainable Roofing Materials

The optimization of thermal performance in buildings is essential for sustainable urban development, yet the high cost and complexity of traditional thermal conductivity measurement methods limit broader research and educational applications. This study developed and validated a low-cost, replicable prototype that determines the thermal conductivity of roof tiles and composites using the Lee Disc method automated with Arduino-based acquisition. Standardized samples of ceramic, fiber-cement, galvanized steel, and steel coated with a castor oil-based polyurethane composite reinforced with miriti fiber (<i>Mauritia flexuosa</i>) were analyzed. The experimental setup incorporated integrated digital thermocouples and strict thermal insulation procedures to ensure measurement precision and reproducibility. Results showed that applying the biocompatible composite layer to metal tiles reduced thermal conductivity by up to 53%, reaching values as low as 0.2004 W·m^-1·K^-1-well below those of ceramic (0.4290 W·m^-1·K^-1) and fiber-cement (0.3095 W·m^-1·K^-1) tiles. The system demonstrated high accuracy (coefficient of variation < 5%) and operational stability across all replicates. These findings confirm the feasibility of open-source, low-cost instrumentation for advanced thermal characterization of building materials. The approach expands access to experimental research, promotes sustainable insulation technologies, and offers practical applications for both scientific studies and engineering education in resource-limited environments.