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Using the Virtual Cybernetic Building Testbed and FDD Test Shell for FDD Tool Development.

pdf icon Using the Virtual Cybernetic Building Testbed and FDD Test Shell for FDD Tool Development. (889 K)
Bushby, S. T.; Castro, N. S.; Galler, M. A.; Park, C.; House, J. M.

NISTIR 6818; 45 p. October 2001.


Architectural Energy Corp., Boulder, CO


BACnet; building automation; building control; direct digital control; energy management systems; fault detection and diagnostics; cybernetic building systems; heating; ventilation; air conditioning; architecture


Advances in building automation technology have taken place for a variety of building services including heating, ventilating, and air conditioning (HVAC) control systems, lighting control systems, access control systems, and fire detection systems. In spite of these advances in technology, many building control systems do not work as intended. It is evident that the industry needs to learn how to take advantage of the new ability to interconnect traditionally independent systems in a building. Commissioning, automated fault detection and new approaches to applying system integration are all areas of active research. However, it can be difficult to conduct this research in actual buildings because of the need to maintain comfortable and safe conditions for the building occupants. This report describes two enabling tools that have been developed to advance these research efforts. It focuses on the use of these tools to develop and test automated fault detection and diagnostic (FDD) technology for HVAC systems and their application in the area of Fault Detection and Diagnosis. The two enabling tools are the Virtual Cybernetic Building Testbed (VCBT) and the FDD Test Shell. The VCBT consists of a variety of simulation models that together emulate the characteristics and performance of a cybernetic building system. The simulation models are interfaced to real state-of-the-art BACnet speaking control systems to provide a hybrid software/hardware testbed that can be used to develop and evaluate control strategies and control products that use the BACnet communication protocol. The FDD Test Shell is a data-sharing tool that was developed to enable side-by-side testing and comparison of two or more FDD tools and to support the integration of information from multiple FDD tools. Preliminary tests of some of the faults modeled in the VCBT are described in this report. The primary goal of the tests was to quantify the impact of valve and damper leakage for typical air-handling unit (AHU) with variable-air-volume (VAV) box configurations. In this study, testing revealed that leakage through the outdoor air damper and a stuck open outdoor air damper fault have almost no measurable impact on the operation of the system.