Energy efficient control of variable speed pumps in complex building central air-conditioning systems

Zhenjun Ma, Shengwei Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

110 Citations (Scopus)


This paper presents the optimal control strategies for variable speed pumps with different configurations in complex building air-conditioning systems to enhance their energy efficiencies. Through a detailed analysis of the system characteristics, the pressure drop models for different water networks in complex air-conditioning systems are developed and then used to formulate an optimal pump sequence control strategy. This sequence control strategy determines the optimal number of pumps in operation taking into account their power consumptions and maintenance costs. The variable speed pumps in complex air-conditioning systems can be classified into two groups: the pumps distributing water to terminal units and pumps distributing water to heat exchanges. The speeds of pumps distributing water to terminal units are controlled by resetting the pressure differential set-point using the online opening signals of water control valves. The speeds of pumps distributing water to heat exchanges are controlled using a water flow controller. The performances of these strategies are tested and evaluated in a simulated virtual environment representing the complex air-conditioning system in a super high-rise building by comparing with that of other reference strategies. The results showed that about 12-32% of pump energy could be saved by using these optimal control strategies.
Original languageEnglish
Pages (from-to)197-205
Number of pages9
JournalEnergy and Buildings
Issue number2
Publication statusPublished - 1 Feb 2009


  • Chilled water system
  • Control strategy
  • Energy efficiency
  • Performance evaluation
  • Pump control

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanical Engineering
  • Electrical and Electronic Engineering

Cite this