OPTIMIZATION OF SUPPLY OUTLET HEIGHT FOR A FAÇADE-MOUNTED DOWNDRAFT EVAPORATIVE COOLER USING CFD-BASED MULTI-OBJECTIVE ANALYSIS OF THERMAL COMFORT AND INDOOR AIR QUALITY
ABSTRACT Evaporative cooling systems are increasingly used as energy-efficient alternative to convention air conditioning in hot climates. However, the thermal comfort and indoor air quality performance of façade-mounted downdraft evaporative coolers strongly depend on the height of the supply outlet. This study investigates the optimal outlet height for a downdraft evaporative cooler installed on the façade of an office space using computational fluid dynamics (CFD). The outlet height was varied from 0.1m to 2.4m above the floor level at increments of 0.1m. For each configuration, the Predicted Mean Vote (PMV) was evaluated at the occupant level (1.1m above the floor) while the Air Change Effectiveness (ACE) was determined in the breathing zone to assess indoor air quality. Multi-objective optimization was conducted with the objectives of achieving maximum ACE while maintaining thermal comfort within 0.5 ≤ PMV ≤ +0.5. Results show that outlet heights between 0.3m and 0.5m satisfy the thermal comfort criteria, while the maximum ACE value (1.1588) occurs at an outlet height of 0.3m. The optimal configuration therefore corresponds to a supply outlet height of approximately 0.3m above the floor level. The findings provide practical design guidance for façade-mounted evaporative cooling systems in office environments located in hot and dry climates.
Authors : Babajo, S.A., Haruna, I.U., Salisu, L. and Soja, Y.J.
Category : Open Access Volume (Issue) : 12(1) Date Uploaded : 5th August 2026