A step-by-step numerical method for optimization of mechanical ventilation in deep underground enclosed parking lots: A case-design study

Abstract

To reduce polluted air, mechanical ventilation (MV) is essential for enclosed parking spaces. The traditional prescriptive design method, the index-based design, cannot guarantee ventilation performance of each fan in the enclosed parking lot. To solve this, the performance-based design approach is the best alternative that specifically addresses performance-related criteria of MV system. In this study of practice-based learning in a real construction project, we proposed a unique design optimization methodology for improving the performance of MV systems using iterative, step-by-step computational fluid dynamics (CFD) simulation. Five numerical simulation levels on seven engineering steps and a techno-economic analysis were utilized. Ultimately, fan selection was based on calculating the airflow and pressure requirements of a MV system and finding a fan of the right design to hedge against the risk of system effect and surging phenomenon. Results showed that a stable fan selection with an error of 5% of the design air flow rate could be implemented by repeating numerical analysis for the performance optimization of the MV system. When the MV design optimization was applied to the reference parking lot, the number of fans could be reduced by 30%, and energy demand of the MV system by at least 16%. Consequently, the annual energy savings was projected to recover the increase in initial investment cost in about 5.8 years. The key contribution of this research is that it overcame the limitations of the traditional index-based design for selecting the optimal fans of MV systems.