To maintain proper indoor air quality and increase energy efficiency, a demand control ventilation (DCV) system has become a popular solution. While DCV systems offer benefits over constant air volume (CAV) systems, their technique is more complex than used in CAV systems. To guarantee the proper operation of DCV system, attention needs to be paid to check the performance of systems.

The results of the carried out study show that only one DCV system performs according to design values in eight public buildings. In all the others, either the airflows were wrong or there was technical fault. However, the indoor air temperatures were within design target values in each space and no complaints about IAQ or thermal comfort were reported by the users.

Two major conclusions can be drawn from this result. Firstly, different kinds of faults seem to be common in the DCV systems. Secondly, these faults are not easy to detect only with the automation system. To guarantee the system performance, post-occupancy evaluation of the system performance