Indoor zyx Air, 3,323-336 zy (1991) z 0 1991 Munksgaard, DK-Copenhagen zy Sensor for Continuous Measurement of the Ventilation Rate zyx in Livestock Buildings z D. Berckrnans', Ph. Vandenbroeck*, and V. Goedseels3 Catholic University of Leuven, Belgium Abstract zyxwvu A zyxwvuts nao zyxwvutsrq turbinemeter zyxwvuts has been developed to be used as a ventilation rate sensor in livestock buildings. On the basis of a pr& smq introduced in 1983, several improvements have been made to develop a low-cost ai- rate sensor with an acceptable accuracy of 60 mjlh in a range fim 200 to 5000 m3/h for pressure d$ ferences fiom 0 to 120 Pa. This sensor can be integra- ted in the climate control equipment of livestock build- ings to improve process control. KEYWORDS: Ventilation measurement, Flow rate measurement. Manuscript received: 12 December 1990. Accepted for publication: 18 June 1991. ' Assistant Professor, National Fund for Scientific Re- search, Laboratory for Agricultural Buildings Re- search ' Assistant, Laboratory for Agricultural Buildings Re- search ' Professor, Laboratory for Agricultural Buildings Re- search Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92,3001 Heverlee, Belgium Problem The Importance of the Ventilating Rate and the Airflow Pattern in Livestock Bu i Id i ngs The ventilation rate through a building is considered to be one of the most important parameters in indoor climate control in live- stock buildings. The recognition of barn ventilation problems and early investigations of them set a milestone in the environmental control of buildings for animal production (King, 1908; Bond, 1976). The influence of airflow rate on the values of physical micro- environmental parameters such as inside temperature, humidity and gas concentration has been discussed by Guss and Grout (1973), Bruce (1975) and Clark and Cena (1981). Car- penter (1974) explains the importance of the ventilation rate by its relationship with air temperature and with the air velocity around the animal. He explains the complexity of the role of the ventilation system by the in- teractions between the indoor climate and other variables, such as the structure of the building, the risk of disease, and the number of pigs in one pen. The objective of the ventilation system is the control of gas concentration, air humid- ity and inside temperature (Bruce, 1981). Consequently, these three quantitative criter- ia determine the ventilation rate through the building and provide the optimum condi- tions for livestock by controlling the physical micro-environment. To achieve this, the two basic funtions of a ventilation system are to provide effective control over the ventilation