Numerical Simulation of Heat and Mass Transfer in Livestock Facilities with Energy-Efficient Negative-Pressure Ventilation

Maintaining a thermally comfortable, hygienic, and energy-efficient microclimate in swine housing is challenging under negative-pressure operation, especially during summer heat and winter drafts. This problem was addressed by comparing 3 supply-air configurations (floor/ground channels, ceiling inlets, and wall channels) using 3D CFD with energy and species transport for humid air and by validating the predicted “temperature – velocity – humidity” fields against on-farm CO2 tracer measurements. The model incorporates heat and moisture loads, as well as realistic fan characteristics; mesh independence and near-wall treatment are also documented. Results show that floor-channel supply yields the most uniform regime (20–26 °C in summer and 16–20 °C in winter), with draft levels not exceeding 0.5 m/s. In contrast, ceiling and wall inlets exhibit stronger near-wall jets and stratification, occasionally exceeding recommended limits. An integral microclimate-efficiency index was introduced to combine thermal comfort, air-quality indicators (CO2/NH3), and specific energy use, as well as to implement a CFD-informed metamodel for rapid selection of inlet angle/height and fan set-points. Practically, the findings help make design and modernization decisions (duct rebalancing, inlet geometry, and pre-cooling), improving welfare and reducing energy consumption.