Climate control of natural ventilated pig houses

Ventilation in pig houses is important for maintaining a good climate for the welfare of animals and humans and for an optimal production. Mechanical ventilation has a good performance, since the ventilation rate can easily be controlled, but it is energy demanding, whereas natural ventilation is cheap but due to large variations in the outdoor conditions it can cause unwanted variations in the ventilation rate. To improve the performance of natural ventilation a good control scheme is necessary. Since in this case controller tuning is difficult in the practical situation, due to all influences on the climate, a dynamic model is discussed, so that the tuning can be done off-line, which means that the tuning of the controllers is done in simulations. The model of the indoor climate is validated by measurements of the temperature of the pig house. The performance of the control scheme, in which standard PID controllers are used in a cascade configuration, is shown by simulations.