Buildings in hot climates experience high solar heat gains that increase cooling energy demand, while freshwater scarcity remains a persistent challenge in arid regions. Conventional solar distillers produce water but do not utilize building heat gain as a useful energy source. This study experimentally investigates a wall-mounted solar distiller (WMSD) designed to simultaneously generate freshwater and reduce building cooling load by intercepting solar heat at the fa & ccedil;ade level. The system employs falling water films over wire mesh surfaces with pulsed circulation and an absorbing nanoparticle coating to enhance evaporation. The results show that increasing basin depth improves thermal stability, raising daily productivity by about 14-19%. Short-pulsed circulation significantly enhances evaporation, providing 20-30% higher output than long cycles. Using two mesh layers yields the best performance, providing increased evaporative area without excessive hydraulic resistance. Under optimal conditions, the daily yield reaches about 7.8 L/m2, the thermal and exergy efficiencies increase by approximately 14% and 12%, respectively, and the water cost decreases by about 11%. When installed on the south facade of a test room, the system reduces wall heat gain and achieves an estimated daily cooling electricity savings of about 0.6 kWh, demonstrating the feasibility of integrating desalination with building energy management.