  As smart buildings move towards open communication technologies, providing
access to the Building Automation System (BAS) through the intranet, or even
remotely through the Internet, has become a common practice. However, BAS was
historically developed as a closed environment and designed with limited
cyber-security considerations. Thus, smart buildings are vulnerable to
cyber-attacks with the increased accessibility. This study introduces the
development and capability of a Hardware-in-the-Loop (HIL) testbed for testing
and evaluating the cyber-physical security of typical BASs in smart buildings.
The testbed consists of three subsystems: (1) a real-time HIL emulator
simulating the behavior of a virtual building as well as the Heating,
Ventilation, and Air Conditioning (HVAC) equipment via a dynamic simulation in
Modelica; (2) a set of real HVAC controllers monitoring the virtual building
operation and providing local control signals to control HVAC equipment in the
HIL emulator; and (3) a BAS server along with a web-based service for users to
fully access the schedule, setpoints, trends, alarms, and other control
functions of the HVAC controllers remotely through the BACnet network. The
server generates rule-based setpoints to local HVAC controllers. Based on these
three subsystems, the HIL testbed supports attack/fault-free and
attack/fault-injection experiments at various levels of the building system.
The resulting test data can be used to inform the building community and
support the cyber-physical security technology transfer to the building
industry.
