Multi-parameter performance optimization for whole year operation of stratum ventilation in offices

Stratum ventilation with proper operation can provide thermal comfort and good inhaled air quality with energy efficiency. Previous studies mainly focused on stratum ventilation for cooling or heating in separate seasons, while little attention on stratum ventilation for whole year operation. Proper year-round operation of stratum ventilation is more complicated, with multiple ventilation operation parameters (i.e., the supply vane angle, supply air velocity, supply air temperature, and air outlet position) non-linearly affecting multiple mutually conflicting criteria of the ventilation performance (i.e., thermal comfort, air quality and energy efficiency). This study optimized the whole year operation of stratum ventilation by using a multi-parameter fitting technology. An experiment on stratum ventilation for both heating and cooling a typical office is conducted. Based on experimentally validated Computational Fluid Dynamics (CFD) simulations, the stratum ventilation performance is investigated. Ventilation effectiveness (E_t) and air distribution performance index (ADPI) are introduced to be as the evaluation indicators to assess the performance of stratum ventilation. Results demonstrate that the mentioned factors play different roles in the thermal performance of stratum ventilation, and exist interactions among each other. The economic-comfort ratio is proposed to assess the indoor comfort and energy consumption simultaneously. Combining with building energy simulation technology and Marquardt method, the optimal year-round parameters of stratum ventilation under four air outlet positions in different climate zones can be determined. This study provides a comprehensive guide for stratum ventilation in practical application.