Ventilation Flow in Pig Houses measured and calculated by Carbon Dioxide, Moisture and Heat Balance Equations

Ventilation flow in commercial livestock buildings can be estimated by means of relatively simple indirect methods based on carbon dioxide (CO2), moisture or heat balances. However, ventilation flow on an hourly basis for these balances needs adjustment for diurnal variation in animal CO2 and heat production. This work examines the agreement between ventilation flow measured in a pig house over a period of 41 days and that estimated from the three balances, on a 24 h and on an hourly basis. The study shows that, all three methods can give reasonably good estimations of the ventilation flow on an hourly basis. On average, the calculated ventilation flow was 8% lower than measured ventilation flow for the CO2 balance, and 9% lower for the moisture and heat balances. A good agreement between measured and calculated ventilation flow was obtained on a 24-h basis (coefficient of determination R2 between 0·92 and 0·97) and on an hourly basis (R2 between 0·83 and 0·92). The study indicates that the agreement between measured and estimated ventilation flow on an hourly basis can be improved by taking into account the diurnal variation in CO2, moisture and heat production.