Estimation of THI index to evaluate thermal stress of animal occupied zone in a broiler house using BES method

Thermal stress of livestock has been issued because this causes reproductive disorders, decreased feed consumption, immunosuppression, and increased mortality rate. THI concept has been widely used to quantitatively evaluate and predict the thermal stress of livestock. However application of this concept in the numerical study is restricted for animals living in the enclosed facilities such as mechanically ventilated broiler house so far, because accurate prediction of indoor micro-climate is very complicated. In this study, Building Energy Simulation (BES) technique was adopted to simulate energy flow and its balance among the systems. Local weather data, insulation characteristics of the building materials, energy generation from broilers according to age, algorithm of ventilation operation were designed for boundary condition of the model. Especially, mechanisms of sensible and latent heat generation from the broilers according to surrounding air temperature and their weight were designed to accurately evaluate the THI values in the mechanically ventilated broiler house. From the BES simulation, excess frequency of the THI threshold for the thermal stress of broilers in Jeju city was highest on the assumption that air conditioning equipment were not installed. When rearing density of 39 kg m^-2 was adopted, total 2,191 hours exceeded in Jeju city. Excess hours of THI threshold were also strongly related to the cumulative air temperature (R²=0.87).