Simplified models of fault effects on unitary air-conditioning equipment for use in building simulation tools

Building performance models most typically do not account for equipment faults, even though such faults are believed to significantly impact performance. One reason is that fault effects on performance are not very well understood, and can be quite complex to model. To address this situation, the current paper provides a summary of known empirical studies of fault effects on air-cooled unitary equipment. The summary includes three important performance parameters – capacity, efficiency, and sensible heat ratio – for three common fault types. Statistical analyses have been used to provide simplified models that can be programmed into building simulation software.