Evaluation of the CO2 mass balance method to calculate ventilation rates from mechanically ventilated livestock buildings

To determine ventilation rates from mechanically ventilated livestock buildings fan-wheel anemometers have been extensively used. This method is reasonably accurate, but the cost of deploying this method is high, especially when a livestock building is provided with a large number of ventilation fans as may be the case in poultry livestock buildings. Here the CO2 mass balance method may provide a cost effective alternative. In this paper, the accuracy of this method for the determination of ventilation rates in mechanically ventilated livestock buildings in The Netherlands was evaluated with existing data from finished and on-going Dutch studies for pig and poultry categories. Fan-wheel anemometers were used as a reference method. The results from this analysis indicated that (under Dutch conditions) the CIGR method could be applied with reasonable accuracy to estimate the ventilation rate from livestock buildings for broilers, fattening pigs, sows and piglets. Using the CIGR method requires accurate registration of the parameters used in the model (animal weight, feed characteristics, and the production of meat/eggs from the animals) and accurate CO2 concentration measurements.