BACS control building services systems across multiple areas. If only one system is integrated incorrectly or inadequately, it can restrict the functionality of all the other BACS.

For example, incoming messages may be misinterpreted or simply not reach the BACS, causing it to react incorrectly or not at all. If information from an access control system is incorrectly received or not received at all, for instance, the heating and sun shading for corresponding rooms may not be controlled appropriately.