Characteristics of airborne transmission with protective flow concept in an office room

Kim Hagström; Weixin Zhao; Simo Kilpeläinen; Panu Mustakallio; Risto Kosonen

doi:10.1007/978-3-032-06810-1_74

Characteristics of airborne transmission with protective flow concept in an office room

Kim Hagström^*
, Weixin Zhao
, Simo Kilpeläinen
, Panu Mustakallio
, Risto Kosonen

^*Corresponding author for this work

Halton Oy

Research output: Chapter in Book/Report/Conference proceeding › Conference article in proceedings › Scientific › peer-review

Abstract

The COVID-19 pandemic was an extremely urgent threat to human life, and similar outbreaks may occur in the future. Due to people spending more than 90% of their time indoors, enclosed indoor environments are among the most high-risk spaces for airborne transmission. Airborne transmission comes from the inhalation of aerosol droplets which are exhaled by an infected person.

Recent studies in office environments show the personal ventilation was effective in reducing the infection risk compared with conventional ventilation. A fully mixed ventilation system requires around a two times higher airflow rate for the same infection risk as the personal system. Despite the promising evidence personal ventilation have not gained wide usage in practical installations. One rea-son might be that the proposed personal ventilation systems require tight integration into to furnishing, while ventilation installations are commonly located in the ceiling.

A new ceiling integrated protective ventilation concept has been developed to over-come above mentioned installation challenge. In previous research it has been applied with promising results in patient environments.

In current research the protective flow concept is applied for office environment. The performance is verified against fully mixed conditions and to various person-al ventilation concepts, which were studied in earlier research with the same lay-out and operating parameters.

Protective flow concept outperforms with a clear margin a fully mixed ventilation that is most commonly used in office environments. The exposure index for protective flow concept is even at the comparable level with the earlier studied localized personal ventilation systems.

Original language	English
Title of host publication	Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025
Subtitle of host publication	Decarbonized, healthy and energy conscious buildings in future climates
Publisher	Springer
Pages	744-751
Number of pages	8
Volume	2
ISBN (Electronic)	978-3-032-06810-1
ISBN (Print)	978-3-032-06809-5
DOIs	https://doi.org/10.1007/978-3-032-06810-1_74
Publication status	E-pub ahead of print - 2 Jan 2026
MoE publication type	A4 Conference publication
Event	REHVA HVAC World Congress: Decarbonized, healthy and energy conscious buildings in future climates - Politecnico Di Milano - Campus Bovisa, Milano, Italy Duration: 4 Jun 2025 → 6 Jun 2025 Conference number: 15 https://climaworldcongress.org/

Publication series

Name	Lecture notes in civil engineering
Volume	763
ISSN (Print)	2366-2557
ISSN (Electronic)	2366-2565

Conference

Conference	REHVA HVAC World Congress
Abbreviated title	CLIMA
Country/Territory	Italy
City	Milano
Period	04/06/2025 → 06/06/2025
Internet address	https://climaworldcongress.org/

Funding

This research was part of the E3 research program funded by Business Finland.

Keywords

airborne transmission
thermal comfort
air distribution
heat gain
exhaust location

Access to Document

10.1007/978-3-032-06810-1_74

Cite this

Hagström, K., Zhao, W., Kilpeläinen, S., Mustakallio, P., & Kosonen, R. (2026). Characteristics of airborne transmission with protective flow concept in an office room. In Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Decarbonized, healthy and energy conscious buildings in future climates (Vol. 2, pp. 744-751). (Lecture notes in civil engineering; Vol. 763). Springer. Advance online publication. https://doi.org/10.1007/978-3-032-06810-1_74

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abstract = "The COVID-19 pandemic was an extremely urgent threat to human life, and similar outbreaks may occur in the future. Due to people spending more than 90\% of their time indoors, enclosed indoor environments are among the most high-risk spaces for airborne transmission. Airborne transmission comes from the inhalation of aerosol droplets which are exhaled by an infected person. Recent studies in office environments show the personal ventilation was effective in reducing the infection risk compared with conventional ventilation. A fully mixed ventilation system requires around a two times higher airflow rate for the same infection risk as the personal system. Despite the promising evidence personal ventilation have not gained wide usage in practical installations. One rea-son might be that the proposed personal ventilation systems require tight integration into to furnishing, while ventilation installations are commonly located in the ceiling. A new ceiling integrated protective ventilation concept has been developed to over-come above mentioned installation challenge. In previous research it has been applied with promising results in patient environments. In current research the protective flow concept is applied for office environment. The performance is verified against fully mixed conditions and to various person-al ventilation concepts, which were studied in earlier research with the same lay-out and operating parameters. Protective flow concept outperforms with a clear margin a fully mixed ventilation that is most commonly used in office environments. The exposure index for protective flow concept is even at the comparable level with the earlier studied localized personal ventilation systems.",

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Hagström, K, Zhao, W, Kilpeläinen, S, Mustakallio, P & Kosonen, R 2026, Characteristics of airborne transmission with protective flow concept in an office room. in Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Decarbonized, healthy and energy conscious buildings in future climates . vol. 2, Lecture notes in civil engineering, vol. 763, Springer, pp. 744-751, REHVA HVAC World Congress, Milano, Italy, 04/06/2025. https://doi.org/10.1007/978-3-032-06810-1_74

Characteristics of airborne transmission with protective flow concept in an office room. / Hagström, Kim; Zhao, Weixin; Kilpeläinen, Simo et al.
Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Decarbonized, healthy and energy conscious buildings in future climates . Vol. 2 Springer, 2026. p. 744-751 (Lecture notes in civil engineering; Vol. 763).

Research output: Chapter in Book/Report/Conference proceeding › Conference article in proceedings › Scientific › peer-review

TY - GEN

T1 - Characteristics of airborne transmission with protective flow concept in an office room

AU - Hagström, Kim

AU - Zhao, Weixin

AU - Kilpeläinen, Simo

AU - Mustakallio, Panu

AU - Kosonen, Risto

N1 - Conference code: 15

PY - 2026/1/2

Y1 - 2026/1/2

N2 - The COVID-19 pandemic was an extremely urgent threat to human life, and similar outbreaks may occur in the future. Due to people spending more than 90% of their time indoors, enclosed indoor environments are among the most high-risk spaces for airborne transmission. Airborne transmission comes from the inhalation of aerosol droplets which are exhaled by an infected person. Recent studies in office environments show the personal ventilation was effective in reducing the infection risk compared with conventional ventilation. A fully mixed ventilation system requires around a two times higher airflow rate for the same infection risk as the personal system. Despite the promising evidence personal ventilation have not gained wide usage in practical installations. One rea-son might be that the proposed personal ventilation systems require tight integration into to furnishing, while ventilation installations are commonly located in the ceiling. A new ceiling integrated protective ventilation concept has been developed to over-come above mentioned installation challenge. In previous research it has been applied with promising results in patient environments. In current research the protective flow concept is applied for office environment. The performance is verified against fully mixed conditions and to various person-al ventilation concepts, which were studied in earlier research with the same lay-out and operating parameters. Protective flow concept outperforms with a clear margin a fully mixed ventilation that is most commonly used in office environments. The exposure index for protective flow concept is even at the comparable level with the earlier studied localized personal ventilation systems.

AB - The COVID-19 pandemic was an extremely urgent threat to human life, and similar outbreaks may occur in the future. Due to people spending more than 90% of their time indoors, enclosed indoor environments are among the most high-risk spaces for airborne transmission. Airborne transmission comes from the inhalation of aerosol droplets which are exhaled by an infected person. Recent studies in office environments show the personal ventilation was effective in reducing the infection risk compared with conventional ventilation. A fully mixed ventilation system requires around a two times higher airflow rate for the same infection risk as the personal system. Despite the promising evidence personal ventilation have not gained wide usage in practical installations. One rea-son might be that the proposed personal ventilation systems require tight integration into to furnishing, while ventilation installations are commonly located in the ceiling. A new ceiling integrated protective ventilation concept has been developed to over-come above mentioned installation challenge. In previous research it has been applied with promising results in patient environments. In current research the protective flow concept is applied for office environment. The performance is verified against fully mixed conditions and to various person-al ventilation concepts, which were studied in earlier research with the same lay-out and operating parameters. Protective flow concept outperforms with a clear margin a fully mixed ventilation that is most commonly used in office environments. The exposure index for protective flow concept is even at the comparable level with the earlier studied localized personal ventilation systems.

KW - airborne transmission

KW - thermal comfort

KW - air distribution

KW - heat gain

KW - exhaust location

UR - https://link.springer.com/book/10.1007/978-3-032-06806-4

UR - https://link.springer.com/book/9783032068095

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BT - Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025

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ER -

Hagström K, Zhao W, Kilpeläinen S, Mustakallio P, Kosonen R. Characteristics of airborne transmission with protective flow concept in an office room. In Proceedings of the 15th REHVA HVAC World Congress - CLIMA 2025: Decarbonized, healthy and energy conscious buildings in future climates . Vol. 2. Springer. 2026. p. 744-751. (Lecture notes in civil engineering). Epub 2026 Jan 2. doi: 10.1007/978-3-032-06810-1_74

Characteristics of airborne transmission with protective flow concept in an office room

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