Preventing mold growth and maintaining acceptable indoor air quality for educational buildings operating with high mechanical ventilation rates in hot and humid climates

Abstract

Educational buildings located in hot and humid climates could suffer from high indoor humidity levels leading to mold growth issues which will eventually affect the well-being of occupants. These unhealthy indoor conditions typically occur in buildings located in extremely humid climates and operating with high mechanical ventilation rates that are normally set to maintain acceptable indoor air quality. Hence, experimental measurements of the indoor conditions of classrooms have been collected and analyzed to evaluate the performance of mechanical ventilation and its impact on indoor humidity, mold growth, and indoor CO2 concentration. Furthermore, a building energy model of a selected classroom building has been developed and coupled with the VTT mold growth model. The simulation environment has then been used to perform a series of sensitivity and optimization analyses to optimize the performance of the HVAC system. The results showed that an occupancy density of 0.5 people/m2 or less is required to deliver optimum ventilation rates, cooling set points, and acceptable indoor CO2 concentrations. Optimum ventilation rates are found to be 2 ACH, 3 ACH, and 3.5 ACH for occupancy densities of 0.2, 0.4, and 0.5 people/m2, respectively, while the optimum cooling set point is 20 °C for all occupancy densities to prevent mold growth. Finally, valuable correlations were obtained in this study that can be utilized further to develop effective optimal control systems capable of improving indoor environmental quality of school buildings in hot and humid climates.