Barriers to application of fault detection and diagnosis (FDD) techniques to air-conditioning systems in buildings in Hong Kong

Automatic fault detection and diagnosis (FDD) is a well-developed technology but its application to buildings remains sparse despite much effort has been made on developing FDD strategies for air conditioning systems. Therefore, this study aimed at identifying the barriers to widespread application of FDD to buildings. The benefit of adopting a new technology is usually uncertain while the initial cost can be high. For providing ballpark figures of the potential energy savings of applying FDD, the avoidable energy penalties of several air-side system and chiller faults were estimated by computer simulation, in the first part of the study.;As accurate and reliable performance measurements are vital to successful application of FDD, operating records of an existing chiller plant were collected for analysis, which unveiled that missing and corrupted data can often occurred. The practices of operation and maintenance (O&M) staff in handling system faults and component failures were also studied, which unveiled another important barrier: a lack of relevant knowledge and skills.;In preparation for developing a FDD algorithm for chillers in the plant where twin-circuit chillers with two screw compressors per circuit were used, a detailed mathematical model that can model such chillers was developed, which was hitherto unavailable. However, the problems with the performance measurement systems in that plant made it impossible to use the plant for trial FDD application.;The second chiller plant on the basis of which the later part of the study was carried out had been incorporated with a chilled water circuit design that allows efficient capture of full- and part-load performance of chillers and was therefore suitable for the study. A model-based chiller FDD strategy was then established, taking into consideration the limitation in the range of measuring instruments available in the plant. The performance indices and thresholds for FDD were developed based on the experimental results of the ASHRAE 1043-RP. The FDD strategy was validated with measurements obtained from the plant and was verified to be effective for chiller FDD.;Finally, the barriers were reviewed from the experience acquired in the study and recommendations were made to tackle the problems.