Air Handling Unit

  • Y. H. Venus LunEmail author
  • S. L. Dennis Tung
Part of the Green Energy and Technology book series (GREEN)


Air handling unit (AHU) is one of the most important equipments in HVAC (heating, ventilation, and air-conditioning) system particularly in large-scale buildings for providing both heating and cooling for multiple zones. This chapter starts with a discussion on AHU and indoor air quality. AHU operations not only significantly impact supply air temperature and humidity levels, but also the energy consumed for heating, cooling, and ventilation. It is essential to implement measures to reduce energy consumption. Various operating modes and ventilation systems of AHU are also discussing. AHU dehumidification by using direct expansion (DX) coil and rotary desiccant dehumidifier is investigated. Furthermore, hybrid systems on integration of rotary desiccant dehumidification with AHU unit and primary handling unit are examined. To illustrate the design of AHU system, a case study on cold vault is presented.


Ventilation Indoor air quality Operating mode AHU configuration Dehumidification and humidification Energy recovery system Cold room 



Flow rate









Cooling coil


Exhaust air


Fresh air


Heating coil


Mixing air


Return air


Outdoor air


Supply air


  1. 1.
    Wargocki P, Djukanovic R (2005) Simulations of the potential revenue from investment in improved indoor air quality in an office building. ASHARE Trans 111:669–711Google Scholar
  2. 2.
    Fanger PO (2000) Indoor air quality in the 21st century: search for excellence. Indoor Air 10:68–73CrossRefGoogle Scholar
  3. 3.
    Kusiak A, Li M (2010) Cooling output optimization of an air handling unit. Appl Energy 87:901–909CrossRefGoogle Scholar
  4. 4.
    Fong KF, Hanby VI, Chow TT (2006) HVAC system optimization for energy management by evolution programming. Energy Build 38(3):220–231CrossRefGoogle Scholar
  5. 5.
    Li S, Wen J (2010) Development and validation of a dynamic air handling unit model. In: ASHARE 2010 winter conferenceGoogle Scholar
  6. 6.
    Yu Y, Woradechjumroen D, Yu D (2014) A review of fault detection and diagnosis methodologies on air handling units. Energy Build 82:550–562CrossRefGoogle Scholar
  7. 7.
    McQuiston FC, Parker JD, Spilter JD (2005) Heating, ventilation, and air conditioning: analysis and Design. Wiley, New YorkGoogle Scholar
  8. 8.
    Khaled M, Ramadam M (2016) Heating fresh air by hot exhaust air of HVAC systems. Case Stud Therm Eng 8:398–402CrossRefGoogle Scholar
  9. 9.
    Zhao Y, Wen J, Wang S (2015) Diagnostic Bayesian networks for diagnosing air handling units’ faults. Appl Therm Eng 90:145–157CrossRefGoogle Scholar
  10. 10.
    Hajidavalloo E, Eghtedari H (2010) Performance improvement of air-cooled refrigeration system by using evaporatively cooled air condenser. Int J Refrig 33:982–988CrossRefGoogle Scholar
  11. 11.
    DOE, Energy efficiency and renewable energy, energy efficiency trends in residential and commercial building, Building Energy Data Book (US Department of Energy)Google Scholar
  12. 12.
    Mazzei P, Minichiella F, Palma D (2005) HVAC dehumidification systems for thermal comfort: a critical review. Appl Therm Eng 25:677–707CrossRefGoogle Scholar
  13. 13.
    Zhang LZ (2006) Energy performance of independent air dehumidification system with energy recovery measures. Energy 31:1228–1242CrossRefGoogle Scholar
  14. 14.
    Pennington NA (1955) Humidity changer for air conditioning. USA Patent No. 2,700,537Google Scholar
  15. 15.
    Dunkle RV (1965) A method of solar air conditioning. Mech Chem Eng Trans Inst Eng 73:73–78Google Scholar
  16. 16.
    Maclaine-cross IL (1985) High performance adiabatic desiccant open-cooling cycle. J Sol Energy Eng 107(1):102–104CrossRefGoogle Scholar
  17. 17.
    Shelpuk B (1993) The technical challenges for solid desiccant cooling. Heat Recovery Syst CHP 13(4):321–328CrossRefGoogle Scholar
  18. 18.
    La D, Dai YJ, Li Y, Wang RZ, Ge TS (2010) Technical development of rotary desiccant dehumidification and air conditioning: a review. Renew Sustain Energy Rev 14:130–147CrossRefGoogle Scholar
  19. 19.
    Waugaman DG, Kinin A, Kettleborough CF (1993) A review of desiccant cooling system. J Energy Res Technol 115(1):1–8CrossRefGoogle Scholar
  20. 20.
    Dhar PI, Singh SK (2001) Studies on solid desiccant-based hybrid air-conditioning systems. Appl Therm Eng 21(2):119–134CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  1. 1.Sustainable Energy LimitedHong KongPR China
  2. 2.Sustainable Energy LimitedHong KongPR China

Personalised recommendations