Investigation of the fan energy and control performance of different damper control strategies in air-handling units

Gang Wang, Li Song, Kaustubh Phalak

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

2 Scopus citations


Outdoor airflow rate, building static pressure, and supply-air-duct static pressure, as controlled variables, are maintained by modulating the speed of the supply and return fans and the position of the outdoor, recirculating, and relief-air dampers in an air-handling unit (AHU). Practically, the three dampers are interlinked completely or partially in order to match independent control inputs with controlled variables and, consequently, form five damper control strategies: the traditional strategy with three dampers interlinked, overlapping and sequenced strategies with the outdoor-air (OA) damper fully open, and ASHRAE overlapping and sequenced strategies. Currently, damper control strategies are evaluated based solely on fan-energy performance. In fact, AHU systems configure a nonlinear network with variant system gains and interactive disturbance inputs. Resultant control issues may degrade energy performance. In this paper, both the fan energy and control performance of five damper control strategies are investigated through steady-state simulation on an AHU using a nonlinear network solution. The sequenced strategy with the outdoor-air damper fully open has the best energy performance, with 4% power reduction over the traditional strategy, but has much worse control performance, with a large outdoor airflow control-gain variation ratio up to 8.9. On the other hand, the traditional strategy has the best control performance with a much smaller outdoor airflow control-gain variation ratio of 2.1. Large outdoor airflow control-gain variations can result in serious deviation between controlled setpoint and actual time response, which leads to equipment deteriorations and potential energy penalties. Therefore, it is recommended that control performance degradation needs to be considered in order to determine the optimal OA damper control strategy.

Original languageEnglish (US)
Title of host publicationASHRAE Transactions
PublisherAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
Number of pages13
ISBN (Electronic)9781936504961
StatePublished - 2015
Event2015 ASHRAE Winter Conference - Chicago, United States
Duration: Jan 24 2015Jan 28 2015

Publication series

NameASHRAE Transactions
ISSN (Print)0001-2505


Other2015 ASHRAE Winter Conference
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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