Optimizing energy efficiency in buildings’ cold water systems: A differential pressure control-based global approach

Abstract

Buildings’ cold water systems have become increasingly complex, with independent equipment control leading to greater energy consumption and greenhouse gas emissions. To improve control efficiency and maximize energy savings, simulation and experimental studies of these systems are essential, although full-scale experimental setups are rare. This paper employs FloMASTER modeling to establish a large-scale practical pipeline network system for validating models, evaluating strategies, and optimizing energy efficiency. The modeling method is validated as accurate, with normalized mean bias error (NMBE) and coefficient of variation of the root mean square error (CVRMSE) values for nodal pressure and flow distribution meeting established evaluation criteria. A quantitative evaluation of constant differential pressure control strategies, considering hydraulic and thermal characteristics as well as energy consumption, reveals that the strategy based on intermediate loop users performs best. This strategy achieves an average hydraulic imbalance rate of only 5.05%, the quickest hydraulic stabilization and restoration time, and comparable secondary pump energy consumption across three control strategies. Furthermore, this simulation study proposes a global combined control strategy that enables more stable operation of the system, reduces chiller energy consumption by 4.66%, secondary pump energy consumption by 9.93%, and overall system energy consumption by approximately 5.38%. These findings suggest that this methodology can be applied to large-scale pipeline networks in complex cold water systems, yielding substantial energy savings.