Sustainable thermal comfort assessment of evaporative cooling systems in hot and arid climates

Rising global temperatures and urbanization have intensified the demand for sustainable cooling solutions, particularly in hot and arid climates such as Iraq, where conventional air conditioning exacerbates energy consumption and greenhouse gas emissions. Evaporative cooling provides an energy-efficient method to reduce ambient temperatures through water evaporation. However, their effectiveness is highly dependent on local climatic conditions. The study objectives were to provide practical insights into the application and limitations of direct evaporative cooling in real-world Iraqi circumstances, beyond technical modeling. A climate-responsive assessment framework for evaporative cooling systems by combining the Köppen climate classification with localized thermal comfort analysis was developed. The effectiveness of evaporative cooling for sustainable thermal comfort was assessed through case studies in major Iraqi cities (Baghdad, Basrah, and Mosul) from 1st May to 30th September under two scenarios: (i) air cooled via direct evaporative processes; and (ii) unconditioned outdoor air delivered through mechanical ventilation. Various modules of the simulation software were used to model hourly air conditions under these scenarios. The results demonstrated that Basrah had the lowest thermal comfort under mechanical ventilation circumstances, with only 6% of summer hours falling into the comfort zone which made it the most vulnerable city in Iraq. Evaporative cooling substantially enhanced the number of thermally comfortable hours during peak summer conditions in Baghdad, Basrah, and Mosul by 41.28%, 54.48%, and 30.55%, respectively, in comparison to scenarios utilizing mechanical ventilation. Integrating climate responsive design and thermal comfort indices through evaporative cooling enhanced energy efficiency and sustainable building performance.