Evaporative cooling photovoltaic-powered ventilation for Mediterranean schools

Most schools in the Mediterranean climate of southern Spain lack mechanical ventilation and cooling systems, leading to inadequate air quality and thermal comfort during the warm season. This issue is critical, as poor air quality and overheating in classrooms negatively affect students' health and comfort. To address this challenge, this study evaluates an evaporative cooling system with photovoltaic-powered mechanical ventilation as a sustainable strategy to mitigate overheating in classrooms. The novelty of the research lies in the integrated assessment of a real-case, renewable-based solution that has been scarcely implemented and insufficiently studied in schools, particularly in hot-dry climates. The methodology included year-long continuous monitoring of hygrothermal conditions and indoor pollutants in classrooms, complemented by short-term controlled campaigns on climatically significant school days for testing specific ventilation and cooling protocols under controlled conditions. Student surveys were also conducted to evaluate perceived comfort and system acceptance, and to compare results with naturally ventilated classrooms under similar conditions. Results indicate that the evaporative cooling system with mechanical ventilation at 1710 m 3 /h maintained adequate classroom indoor air quality and thermal comfort with outdoor temperatures under 32.7 °C, with 73.2% of students voting around thermal neutrality. The estimated monthly energy consumption was 176 kWh, fully offset by a 1.35 kW capacity photovoltaic field per classroom. In the cold season (9–15 °C), adequate classroom thermal conditions were achieved with 570 m 3 /h, requiring limited morning heating. Overall, this integrated low-energy solution effectively and sustainably improves classroom air quality and mitigates overheating in hot-dry climates. • 1710 m 3 /h evaporative cooling airflow met adaptive comfort below 32.7 °C outdoors. • Early heating and 570 m 3 /h airflow at 9–15 °C outdoors met comfort and CO₂ targets. • System kept CO₂ under control, yet filtration is needed for other substances. • System energy use per classroom can be offset with 1.35 kW photovoltaic generation.