Statement Screening of measurement methods for determination of ventilation rate when performing emission measurements in livestock housing
To determine the emission of pollutants from livestock housing, two parameters are measured. One parameter concerns the concentration difference of the pollutant between the stable air and the outside air. The other parameter concerns the amount of air leaving the stable, specifically the ventilation flow rate. By combining the difference in concentration in the entering and leaving air of the stable with the ventilation flow rate, the emission can be calculated (Hassouna et al.et al., 2016). To determine the ventilation rate of a stable, a distinction is made between mechanically and naturally ventilated houses according to the following definitions.
Mechanically ventilated stable = livestock housing with well-defined air inlets and outlets, where the air leaves the house through an outlet/ventilation shaft (VERA, 2018b). In mechanically ventilated stables, fans create an airflow that extracts the stable air through the ventilation shaft(s) via negative pressure. Air intake through vents is regulated (automatically) to maintain a stable indoor climate. Poultry, pig and veal calf stables are mainly mechanically ventilated in Flanders.Naturally ventilated barn = barn where ventilation relies primarily on natural ventilation. This type of housing contain air vents on the sides and/or in the ridge of the roof. Air circulation can be additionally stimulated by placing fans in the barn. In addition, air intake can be limited by (partially) closing off the air openings via (automated) screens. Dairy and beef cattle housing is mainly naturally ventilated in Flanders.
This report focuses on the measurement methods that can be used to determine the ventilation rate when performing emission measurements in livestock housing. After the description of the various available measurement methods (Chapter 3), the fourth chapter lists which measurement methods are allowed or 'recognized' in various (inter)national measurement protocols for the determination of the ventilation rate in stables. The report discusses the possible measurement methods (Chapter 4) and ends with a conclusion (Chapter 5) on measurement methods for determining the ventilation rate in a stable.