Paper Conference

Proceedings of ASim Conference 2016: 3rd Asia conference of IBPSA-China, Japan, Korea


Probabilistic distribution of system performance output from BEMS by heat source system simulation incorporating error consideration

S. Miyata, Y. Akashi, J. Lim, Y. Kuwahara

Abstract: Commissioning (Cx) is indispensable for efficient operation of a heat source system, and is often implemented by comparison between simulation results and real building energy management system (BEMS) data. However, a heat source system that is composed of various pieces of equipment with complex controls will have numerous errors. Therefore, real BEMS data should be compared to simulation results with a distribution that considers errors. However, simulating errors is very complicated and has not yet been studied in this context. In this study, a simulation for an existing heat source system was developed, errors were incorporated into the simulation, and the distribution of the system coefficient of performance (SCOP) was elucidated. Errors were categorized according to location: at sensors, direct digital controllers (DDC), actuators, and the integrated controller. Error probability distributions were modeled based on a normal distribution. After 1000 simulation runs with inputs comprising the real cooling load and environmental conditions in August 2015, the distribution of SCOP was normally distributed. Its average was 0.8 % lower than SCOP without errors, and its two-sided 95 % confidence interval was from approximately −7.8 to 6.0 % from the average. Considering the above, the distribution of simulated SCOP appears to help improve Cx efficiency through enabling identification of where the real SCOP lies in relation to the errors. The model of errors in this study relied on some assumptions. Therefore, more appropriate modeling, adapted to the specific equipment used, would make the distribution better fitted. Future research should investigate which errors have the greatest influence on SCOP, which will help maintain the system more efficiently.
Keywords: Heat source system, Simulation, Errors, Distribution of performance, Commissioning