The Recovery Effect in Work Efficiency by Temporary Stimulative Airflow
Authors: Ito Kyoko , Tsuji Yuta , Ishii Hirotake , Shimoda Hiroshi , Taniguchi Kazuhiro , Obayashi Fumiaki 
Published: April 2022

In recent years, research to improve the efficiency of intellectual work by improving the office environment has been pursued and has produced significant results [1]. Among the indoor environments that affect intellectual work, the thermal environment has been the subject of many studies because of its significant impact on intellectual work. Regarding airflow as one of the factors, the DR (DraftRisk) model [2] , which predicts discomfort of airflow in a cool environment, and the PS (Percentage of Satisfied People) model[3], which predicts comfort in a warm environment, have been studied. The psychological effects of airflow properties such as turbulence [4] and fluctuation [5] as well as velocity have also been studied.The purpose of this study is to examine temporary stimulative airflow to effectively recover the efficiency of intellectual work and to confirm its effectiveness. This study uses the efficiency of intellectual work as an indicator of the impact of temporary stimulative airflow.First, based on the results of preliminary experiments, two types of airflow were selected. Next, we conducted an experiment to examine the effects of these airflows. Nine participants in the experiment performed a cognitive task. The work efficiency was measured from their work performance, and the airflow was exposed by detecting a decrease in the arousal level of the participants. To detect the decrease in arousal level during the work, PERCLOS (PERcent of eyelid CLOSureover pupil) [6] was used as a measurement index of arousal level. In addition to the measurement of arousal level by PERCLOS, the activity state was measured by several physiological indices. Electroencephalogram (EEG) was measured as an indicator of brain activity, and electrocardiogram (ECG) and skin potential, which indicate autonomic nerve activity, were measured as indicators of body activity.As a result, six out of nine participants were included in the analysis. Twenty-six airflows were delivered to the six participants. Then, as a result of analyzing before and after exposure to the airflow, we analyzed various indices when work efficiency was recovered by exposure to the proposed airflow.From the results of physiological indices, when PERCLOS exceeded the threshold before the airflow exposure, there was an increase in alpha waves (EEG) indicating rest etc., and a continuous decrease in the LF/HF ratio of the heartbeat indicating sympathetic dominance. In addition, fluctuations in skin potential were observed during the airflow exposure. Furthermore, after the airflow exposure, alpha wave (EEG) dominance was no longer observed, and the LF/HF ratio showed an upward trend. Comparing the measurement results before and after the start of the airflow exposure, the power of alpha wave of EEG increased before the start, but was suppressed after the exposure.In the future, we would like to improve the proposed airflow stimulus in order to sustain the recovery effect of the airflow stimulus, and consider the experimental design to expose the airflow before the arousal level decreases too much. In addition, it is expected that the design of airflow to increase the recovery effect of airflow stimulation would lead to even greater performance recovery effect.[1] Lawrence Berkley National Laboratory: Indoor Air Quality, Scientific Findings Resource Bank, http://www.iaqscience.lbl.gov/ (2021-10-22).[2] P. O. Fanger, N. K. Christensen: Perception of draught in ventilated spaces. Ergonomics, Vol. 12, pp. 215-235 (1986).[3] M. Fountain, E. Arens, R. J. de Dear, F. Bauman, K. Miura: Locally controlled air movement preferred in warm isothermal environments, ASHRAE Trans., Vol.100, pp. 937-952 (1994).[4] E. Mayer: Physical causes for draft: some new findings, ASHRAE Trans., Vol.98, pp. 540-548(1987).[5] S. Tanabe, K. Kimura: Importance of air movement for thermal comfort under hot and humid conditions, ASHRAE Trans., Vol.100, pp.953-969(1994).[6] D. F. Dinges, R. Grace, Perclos: A valid psychophysiological measure of alertness as assessed by psychomotor vigilance, FHWA-MCRT-98-006, US Department of Transportation, Federal highway Administration (1998).