Model-based optimal control of outdoor air flow rate of an air-conditioning system with primary air-handling unit

Zhongwei Sun, Shengwei Wang, Na Zhu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

20 Citations (Scopus)


This paper presents a model-based outdoor air flow rate optimal control strategy for multi-zone variable air volume air-conditioning systems with the primary air-handling units. An adaptive optimisation algorithm is adopted for optimising the set point of the outdoor air flow rate to minimise the energy cost, which could compromise the energy consumption of the primary fan and the cooling energy saving by the cold outdoor air. The primary fan energy consumption can be predicted using a simplified incremental fan model and the main parameters of this model are identified online. The cooling energy saving by the outdoor air is estimated online using the enthalpies of the air streams. The lower limit of the outdoor air flow rate is determined by a CO2-based adaptive demand-controlled ventilation strategy using the dynamic multi-space equation to maintain the satisfied indoor air quality (IAQ). Tests were conducted to evaluate the performance of the control strategy applied to a practical building system in simulation environment. The results show that the proposed optimal control strategy can reduce energy consumption significantly, while maintaining a satisfactory IAQ. Reprints and permissions:
Original languageEnglish
Pages (from-to)626-637
Number of pages12
JournalIndoor and Built Environment
Issue number6
Publication statusPublished - 1 Dec 2011


  • Incremental adaptive model
  • Model-based control
  • Optimal control
  • Primary air-handling unit
  • VAV air conditioning
  • Ventilation control

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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