Swine Finishing Room Air Infiltration Quantification-Modelling and Use in Ventilation System Design

Modern day swine production buildings used for commercial pork production in the Midwestern region (severe winters and moderately hot summers) of the US are typically ventilated using negative pressure mechanical ventilation systems (VSs). The combinations of fans and inlets (diffusers) are typically used for ventilating the buildings during winter and spring time. The design of ventilation systems for swine finishing rooms (there may be one or more rooms in a swine barn, Jadhav et al., 2015) is not a simple task for practicing engineers due to complexities of air flow behavior, varying outside climate, and environmental requirements of animals. In addition, air infiltration (AI)-an integral part of negative pressure VSs, makes the design process increasingly complex. Due to AI, VSs perform in a nonoptimum manner. Non-optimum ventilation systems deliver insufficient or excess air flow rates where needed and are responsible for the unsatisfactory environment for animals (Albright, 1990). Optimal performance of VSs for livestock rooms (LRs), such as swine finishing rooms (SFRs), can be achieved by maintaining proper pressure difference (PD) across the room/inlets (Albright, 1990). Zhang et al. (2001) recommended the PD range for LRs between 10 and 20 Pa while, Albright (1990) recommended a minimum PD of 10 Pa across LRs, with 10 to 15 Pa PD desired to resist wind speeds up to 40 Km/hr. Furthermore, during cold weather periods, design ventilation rates (DVRs) are minimum for LRs and, in some cases, dominated by AI rates of the rooms (Albright, 1990). Low required DVRs along with high potential AI rates makes it difficult if not impossible to maintain a desired pressure difference (DPD) across a SFR. In this study, the AI rates of Midwestern style SFRs were quantified and modelled and a procedure was developed for active use of AI in the design of the VSs. The AI rates were