Measurement of air velocity in animal occupied zones using an ultrasonic anemometer

Abstract

The air velocity in the animal occupied zone (AOZ) of a pig facility influences the thermal comfort of pigs and is affected by the ventilation system in the building. Little is known about the relationship between the air velocity in the AOZ and the ventilation system design. This article describes the development and a practical test of an air velocity measuring system in the AOZ using ultrasonic anemometers. The anemometers were protected by a wire protection cage, which resulted in a lower air velocity measurement that was corrected by a linear correction factor of 0.83. A suitable aggregation interval for time-averaged air velocity measurements in occupied pens was 300 s. The effect of animal activity on the measured air velocity was minimal and therefore neglected, but the location of the anemometer in a pen was deemed important. A representative location was above the resting place of the animals over the solid floor. The presence of an anemometer in a pen resulted in some minor changes in the lying behavior of the animals. In the experimental door-ventilated room with weaned piglets there was a clear (0.04 m/s) and significant difference in average air velocity between pens 3 and 9 (P <0.001). The maximum air velocity of 0.15 m/s advised was exceeded in 21% of the time a pen in the back of the room. In a pen closer to the door, air velocities appeared to be too high less than 2% of the time. The measuring system described in this article can be combined with air quality and temperature measurements in the AOZ for determination of the performance of ventilation systems and comparison of ventilation systems