Ventilation rates in mechanically-ventilated commercial poultry buildings in Southern Europe: Measurement system development and uncertainty analysis

Measuring ventilation rate in intensive livestock buildings is important to improve the indoor environment and to determine the emission of gas pollutants from the building. However, measuring ventilation rates in commercial animal houses is difficult in practice. In this study a system to measure ventilation in a mechanically-ventilated commercial broiler farm with constant flow fans is presented. The system consisted of a low voltage DC circuit, connected to the signal circuit of the fan motor relays. Ventilation rate was determined hourly in one summer and one winter cycle (46 and 36 days, respectively), and the uncertainty of the measurements carried out by this system was evaluated. The system yielded accurate information regarding the time of operation of each fan and hourly ventilation rate, provided that the ventilation rate of each fan was known. Uncertainties in airflow measurement were evaluated using numerical Monte Carlo methods, being on average less than 10% of the measured value. The influence of the sampling frequency of fan status and the measurement of a partial number of fans in the building on the final uncertainty was also quantified. The ventilation rates and uncertainties determined using the developed system are valuable to determine total emissions and temporal emission patterns.