Evaluating the Impact of Reflective Painting on Building HVAC Performance

This study investigates the impact of applying reflective paint to building walls on cooling energy demand and surface heat emission. A multi-story research building was simulated using DesignBuilder, with wall reflectivity values ranging from 0.1 to 0.9. Two HVAC configurations were compared: a centralized Fan Coil Unit (FCU) system and a decentralized Packaged Terminal Air Conditioner (PTAC) system. The results indicate that increasing wall reflectivity through reflective paint significantly reduces cooling energy consumption and site heat emissions, particularly during the summer months. In the FCU system, cooling energy demand decreased by up to 7.27%, while surface heat emissions were reduced by as much as 86.59%, in comparison to a baseline reflectivity of 0.5. The PTAC system demonstrated even greater sensitivity, with cooling energy savings of up to 7.96% and heat emission reductions exceeding 120% compared to the baseline. In contrast, low-reflectivity wall surfaces led to higher cooling loads and surface heat emission. In addition, higher reflectivity produced modest reductions in outdoor air temperature, with the strongest cooling effect occurring during late morning peak solar hours. Outdoor air temperature exhibited a consistent trend relative to the 0.5 baseline, ranging from a maximum increase of +0.36% at 09:00 using reflectivity of 0.1 to a maximum decrease of -0.41% at 09:00 using reflectivity of 0.9, with the effect reducing toward evening. Overall, the findings highlight that reflective wall paint can enhance HVAC efficiency, offering a low-cost passive strategy for enhanced energy savings and urban heat mitigation in hot-humid climates.