Work

Droplet fate and infection risk under ceiling fan integrated air conditioning: cough and speech scenarios

Year: 2026

Type: article

Abstract: Ceiling Fan-Integrated Air Conditioning (CFIAC) is a coupling configuration of air conditioning ventilation systems and ceiling fans that combines fresh air supply (from the air conditioning system) with indoor airflow distribution adjustment (via ceiling fans). This study employed Computational Fluid Dynamics to simulate the transient respiratory droplet dispersion under CFIAC systems. By combining infection risk for the exposed person and droplet fate indicators (suspension, sedimentation, escape), the impacts of different ventilation configurations, ceiling fan speeds, and exhalation types on droplet transmission were investigated. Ceiling fan activation was found to either mitigate local infection risk or enhance airflow circulation: downward operation at 72 rpm reduced local infection risk by 96.6%, while upward rotation decreased the fraction of suspended droplets by 39.29% (boosting droplet escape by 10.88-fold relative to fan-off conditions). Excessively high fan speeds (122 rpm) negated these benefits, increasing infection risk by 4.25-fold compared to the 72 rpm condition. CFIAC systems exhibited more effective control over coughing droplets than over speaking droplets, with the infection risk associated with speaking being 15.5% higher than that of coughing. Among the tested configurations, upper-supply and ceiling-exhaust ventilation excelled in reducing local infection risk, while upper-supply and lower-exhaust ventilation optimized overall respiratory droplet control. These results provide practical guidance for optimizing CFIAC operation and formulating targeted infection prevention strategies.

Source: Energy and Built Environment

DOI: 10.1016/j.enbenv.2026.02.002

Authors: Liming Kang, Xinghui Zhang, Cong Zhang, Bin Cao, Yingxin Zhu, Xinyu Jia

Institutions: Taiyuan University of Technology, Tsinghua University

Language: English

Topic: Infection Control and Ventilation

Subfield: Pulmonary and Respiratory Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: diamond

Funders: ShanXi Science and Technology Department, Shanxi Provincial Education Department