Thermal Performance of Aerogel Composite Coatings for Building Temperature Regulation

Building cooling accounts for a significant portion of energy consumption in tropical countries. Conventional cool paints mainly rely on solar reflectance to reduce heat absorption. However, their effectiveness is highly dependent on surface colour and coating durability. Silica aerogel (SA), which possesses ultra-low thermal conductivity, high porosity, and low density, offers a promising alternative for thermal insulation applications. In this work, silica aerogel derived from incineration bottom ash was incorporated into a water-based coating system for building thermal regulation. The thermal performance of the developed aerogel composite coatings was evaluated under both laboratory-simulated and rooftop environmental conditions. In this work, the effectiveness of aerogel coatings as a passive cooling and retrofit solution for buildings was studied. Silica aerogel synthesized from incineration bottom ash was incorporated into a water-based coating matrix and applied at different thicknesses ranging from 0.5 mm to 2.0 mm. A controlled experimental chamber measuring 2.0 m × 1.5 m × 1.2 m was constructed to simulate industrial laboratory conditions subjected to external thermal loads. Thermal and environmental parameters were continuously monitored using infrared temperature sensors integrated with real-time clock modules and SD-card-based data logging systems. Data acquisition was conducted at one-minute intervals over a testing duration of seven days. The results demonstrated that increasing coating thickness significantly improved thermal insulation performance. The average indoor temperature decreased from 29.26 °C for the uncoated condition to 25.81 °C for the 2.0 mm coating, corresponding to a temperature reduction of 3.45 °C. A comparative rooftop experiment using a coated glass panel measuring 1.6 m × 1.0 m showed that the aerogel coating outperformed a commercially available cool paint in reducing heat transfer. In conclusion, the aerogel composite coatings can potentially be used as a lightweight and retrofittable passive cooling solution for energy-efficient buildings and industrial facilities.