Variable-frequency drive applications in nonmakeup-air exhaust systems

G. Wang, M. Liu

Research output: Contribution to journalArticlepeer-review


The constant-speed fan wastes fan energy and causes excessive noises in nonmakeup-air exhaust systems, where stack-exit velocity decreases proportionally to the laboratory exhaust airflow. A variable-frequency drive (VFD) can maintain the required static pressure at the fume hoods by modulating the fan speed. The VFD reduces the fan power and eliminates the noise problems. A theoretical study has been conducted to investigate the system performance of the constant fan nonmakeup-air exhaust system, the impacts of the VFD, and the optimal VFD control for multiple-stack systems. The results show that the VFD can potentially reduce annual fan energy of the constant-speed fan nonmakeup-air exhaust systems by as much as 51%.

Original languageEnglish (US)
Pages (from-to)134-140
Number of pages7
JournalJournal of Architectural Engineering
Issue number4
StatePublished - Dec 1 2003
Externally publishedYes


  • Buildings
  • Energy consumption
  • Fans
  • Speed control

ASJC Scopus subject areas

  • Architecture


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