Jungsuk Lee1, Jung-Hun Noh1,2, Kwang-Chul Noh3, Young-Won Kim4, Se-Jin Yook This email address is being protected from spambots. You need JavaScript enabled to view it.1 

1 School of Mechanical Engineering, Hanyang University, Seoul 04763, Korea
2 R&D Center for Research and Business Cooperation Mechatronics Team, Institute for Advanced Engineering, Yongin 17180, Korea
3 Air Lab, Gwangju 61478, Korea
4 International Research Center for Geothermal Energy, Korea Institute of Industrial Technology, Gwangju 61012, Korea

Received: August 26, 2020
Revised: December 2, 2020
Accepted: December 28, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.200533  

  • Download: PDF

Cite this article:

Lee, J., Noh, J.H., Noh, K.C., Kim, Y.W., Yook, S.J. (2021). Effect of a System Air Conditioner on Local Air Quality in a Four-bed Ward. Aerosol Air Qual. Res. 21, 200533. https://doi.org/10.4209/aaqr.200533


  • Effect of system air conditioner (SAC) on air quality in a four-bed ward was studied.
  • Ventilation system (VS), air cleaner (AC), and ward curtains were also considered.
  • Decay rate and age of air were the indicators for ventilation efficiency assessment.
  • Local air quality was greatly affected by the position of SAC relative to VS or AC.
  • When curtains were used, operating SAC solved stagnant flow phenomenon to some degree.


In a ward where many patients are hospitalized, effective ventilation is important because airborne viruses may cause secondary infection. This study investigates the changes in the air quality in a four-bed ward according to the use of a ventilation system (VS), an air cleaner (AC), a system air conditioner (SAC), and personal curtains. The age of air was obtained both experimentally and numerically, and used as an indicator for the ventilation efficiency assessment. Consequently, the air flows from the outlets of the four-way cassette SAC could interfere with or contribute to the introduction of fresh air depending on the positions in the ward. For positions where the fresh air could not reach easily when only the VS was used, the air quality was improved by the additional use of the SAC. While the use of personal curtains prepared for each bed interfered with the air flow in the ward and resulted in local spots with poor air quality, the operation of both the VS and the SAC enhanced the air flow and improved the local air quality. The overall indoor air quality was improved when the AC was used. However, the ventilation efficiency was reduced when the SAC was operated along with the AC, and the air quality deteriorated at positions where the flow caused by the SAC and that by the AC interfered with each other.

Keywords: Indoor air quality, Age of air, System air conditioner, Ventilation system, Air cleaner

Don't forget to share this article 


Subscribe to our Newsletter 

Aerosol and Air Quality Research has published over 2,000 peer-reviewed articles. Enter your email address to receive latest updates and research articles to your inbox every second week.

Latest coronavirus research from Aerosol and Air Quality Research

2018 Impact Factor: 2.735

5-Year Impact Factor: 2.827

SCImago Journal & Country Rank

Aerosol and Air Quality Research (AAQR) is an independently-run non-profit journal, promotes submissions of high-quality research, and strives to be one of the leading aerosol and air quality open-access journals in the world.