Energy analysis, optimal high-limit control and engineering approach of air-side economizers

Gang Wang, Li Song

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


Most air-handling units in commercial buildings adopt an air-side economizer to use outdoor air for free cooling when the outdoor air is cool or cold. An economizer changeover is sequenced by high-limit controls for outdoor air. Several highlimit controls have been specified with consideration of climate zones and availability of humidity measurements. However, confusion regarding optimal outdoor air high-limit curves and the lack of accurate humidity measurements are major barriers to achieve maximum economizer energy savings. To obtain a comprehensive understanding of economizer high-limit controls and to identify an alternative for effective economizer operations, optimal high-limit curves are studied by simulating and comparing the energy consumption between minimum outdoor air and economizer modes of an air-handling unit. Investigation of impacts on optimal high-limit curves reveals that supply air temperature can replace return air humidity to attain optimal high-limit curves. A practical engineering approachfor economizer control also is investigated by the use of internet weather data to substitute for local outdoor air humidity measurements.

Original languageEnglish (US)
Title of host publicationASHRAE Transactions
PublisherAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
Number of pages14
ISBN (Electronic)9781936504824
StatePublished - 2014
Event2014 ASHRAE Annual Conference - Seattle, United States
Duration: Jun 28 2014Jul 2 2014

Publication series

NameASHRAE Transactions
ISSN (Print)0001-2505


Other2014 ASHRAE Annual Conference
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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