Analysis of local mean age and air supply effectiveness in a piglet house using the tracer gas decay method

Evaluation of Actual Ventilation Rates and Efficiency in Research-Scale Pig Houses Based on Ventilation Configurations

“…However, during the initial phase, when ventilation starts, the CO 2 concentration reduction pattern at each location is unstable due to the sudden opening of inlets and the exhaust fans starting, leading to unstable indoor airflow. Considering this unstable period can lead to the overestimation or underestimation of ventilation effectiveness [13,20]. Therefore, we excluded this initial unstable period and defined the starting point (t 1 ) as the time when the CO 2 concentration at each location reached 4000 ppm [13].…”

“…Considering this unstable period can lead to the overestimation or underestimation of ventilation effectiveness [13,20]. Therefore, we excluded this initial unstable period and defined the starting point (t 1 ) as the time when the CO 2 concentration at each location reached 4000 ppm [13]. Consequently, the results from this study are relevant for cases where ventilation operation is sustained for a long period; however, they are inappropriate for scenarios where the ventilation system operates intermittently for a few seconds, such as during the winter season.…”

“…Ventilation effectiveness concerns the quality and supply of air distribution [9]. In order to accurately determine ventilation effectiveness, several ventilation effectiveness indices must be considered, such as the air diffusion performance index [10], air change effectiveness based on the concept of air's age [8,[10][11][12][13], temperature effectiveness [10,12], pollutant removal efficiency [11,12], the percentage of outside air [11], and draught rating [12]. In addition, air changes per hour (ACH) or the air exchange rate is a common index that denotes the number of times the specific air volume within a livestock building is replaced with fresh air in one hour [14][15][16][17][18].…”