USING OUTSIDE TEMPERATURE TO PREDICT ODOUR EMISSION FROM MECHANICAL VENTILATED LIVESTOCK BUILDINGS

Odour emission of livestock buildings is of interest for the residents in the vicinity of animal husbandry due to its annoying potential. To apply a Gauss dispersion model to odour emissions, the emission parameters have to be known. The emission parameters of a mechanically ventilated livestock building, the odour flow and the volume flow of the outlet air, are calculated by combining a steady-state balance model to assess the outlet air temperature and the volume flow with a simple model for the odour release inside the livestock building. The calculations were done for a two-year period based on half hour values of the emission and meteorological parameters. The results show a distinct diurnal and annual variation of the odour concentration due to the variability of the volume flow. The mean odour concentration during daytime in the summer months lies in a very narrow range close to the overall minimum. Odour concentration derived from odour emission and the maximum volume flow of the animal house is useful for model calculations. During a clear-sky summer period, the model predicts a night-time odour concentration of about 4.6 times the daytime concentration due to the reduced volume flow at night. To improve the calculation of odour concentrations by dispersion models, the annual and diurnal variation of the odour release has to be taken into account. The model suggests that long term measurements of the odour emissions of animal houses are necessary for regulatory and legal purpose