Influence of Indoor Environment Changes in Relaxation Space on Relaxation and Refreshment Effects of Occupants

. Since proper break between office work is helpful in decreasing work-related stress and fatigue, a break space in office is also an important place to create healthy and productive workplace environment. However, there are relatively few studies focused on the break space compared to ones focused on work space. In this study, experiments were carried out to investigate the influence of the break space’s indoor environment on occupants’ psychological and physiological responses. To examine whether change in indoor environment during break positively affect occupants’ responses and productivity, lighting, odor and air movement conditions were intentionally changed before the end of the break. As for the psychological response, there was a possibility that it would be affected when the lighting and air movement were changed. As for brain waves, effects were also observed when lighting and air movement were changed. In terms of productivity, performance was better when the environment was changed than when the environment was left unchanged during breaks. The need for breaks was indicated because the worst results were obtained when the work was done continuously without a break in the first place. The best results were obtained when the environment was changed to generate an odor


Intorduction
While working long hours in an office is believed to reduce concentration and affect work efficiency, taking breaks in between has the effect of increasing w o r k e ff i c i e n c y, a n d t h u s b r e a k s d u r i n g t h e workday have been recommended in recent years. 1) However, little research has been conducted on the effects of the break space environment on subsequent work session efficiency and on the psychological and physiological responses of the occupants. The purpose of this study is to propose a break environment design that improves the comfort and productivity of occupants through field experiment. In this experiment, lighting, odor, and air flow were changed during breaks, and the psychological and physiological responses of occupants and work efficiency after breaks were measured. Based on the results, the impactor changes in the indoor environment during breaks may lead to improved work efficiency after the breaks is examined.

Experiment Summary
The experiment was conducted in a laboratory in Task (1) Task (3) Task (3) Task (3) Task (1) Task (1) Task (   Osaka University,Japan (Fig.1). The panel consisted of fi ve male (22-24 years old) and four female (21-24 years old) students of the University. The experimental schedule is shown in Fig.2. The panel was briefed in the work space and fi tted with EEG sensors; after the fi rst psychological evaluation,participants performed two d2 tests and a Sudoku, followed by two d2 tests for a total of 15 minutes (task (1)). After the second psychological evaluation, the panel was allowed to rest for 10 minutes in the rest space.The fi rst 8 minutes of the rest period was spent watching nature images, hereafter referred to as "relaxed state". For the remaining 2 minutes, the effect of changing the break room conditions was investigated. Lighting (L), airfl ow (W), and odor (O), or all of them (A) were changed. This state is hereinafter referred to as the refresh state. For comparison, an experiment in which participants spent 10 minutes in a relaxed state (R) and a condition in which they worked continuously for about 45 minutes without a break (T) were conducted. After the third psychological evaluation, which took place after the break, the participants moved to the workspace and performed the d2 test and Sudoku for 15 minutes as before the break (task (3)). Finally, a fourth psychological evaluation was conducted.To avoid the influence of sunlight, the windows of the laboratory were covered with lightshielding film. In the work space, the desk surface illuminance and color temperature were standardized to 750 lx and 3900 K, respectively, and the space was separated by partitions so that the experimenter could not be seen.The rest area was equipped with light bulbs with variable illuminance and color temperature. The rest room in the relaxed state was standardized with a face illuminance of 100 lx, a color temperature of 3500 K, no odor spray, and no air flow. Experimental conditions are shown in Table 1.In the refreshment condition, in the varying illumination cases, the illuminance was varied from 100 lx to 3500 lx and the color temperature from 3500 K to 5700 K.In the odor case, peppermint essential oil was sprayed, and in the airflow case, airflow was generated by a fan. The measured psychological and physiological responses are shown in Table 2.Physiological responses included electrocardiogram(ECG), chest temperature (TDK, Silmee Bar type Lite), and electroencephalogram (Miyuki Giken, MP208), while psychological responses were measured by answering a questionnaire. For EEG, O1 and O2 (occipital area) were measured according to the international 10-20 method.

Experimental Results and Discussion of Psychological Responses
To begin with, the psychological reactions results are reviewed. Fig. 3 shows the average values of all panels in the subjective evaluation items. The subjective evaluation of the room environment before and after the break shows a significant decrease only for case (A), compared to the pleasantness of the room environment as shown in Fig. 3(e). This indicates that large environmental changes during breaks may make the occupants uncomfortable. Looking at the pleasantness/unpleasantness of the odor in Fig. 3(b), there is not much difference between the results for case (O) in which the odor changed, and case (A), and the results for the other conditions, but these two factors tend to divide the responses, and it is likely that the averaged results canceled each other out. Fig. 4 (a) shows the odor pleasantness and unpleasantness for Panels 1 and 2. Panel 1 found the smell of peppermint somewhat pleasant, while Panel 2 found the smell somewhat unpleasant.The airflow pleasantness in Fig.  3(c) shows that the post-break case (W) and case (A) were rated on the unpleasant side, while the airflow   (2023) https://doi.org/10.1051/e3sconf/202339601059 IAQVEC2023 pleasantness in Fig. 4(b) shows that panel 2 finds it unpleasant while panel 5 finds it pleasant.In this case, six panels answered that the airflow was unpleasant, while two answered that it was pleasant.In Fig. 3(d), the pleasantness of the lighting shows that condition (L) and condition (A) are on the unpleasant side after the break. No panel showed an increase in the rating before and after the break for condition (L) and condition (A) in the pleasantness of the lighting.
There are factors for which the initial values differ significantly even for the same panel, one of which is the level of fatigue.The effects of the difference in the initial values of the degree of fatigue on the other subjective evaluation factors should be analyzed.  Fig 5(c) and (d) show that at the pre-work point in Panel 2, case (O) is three levels higher than case (W) in terms of the level of comfort and discomfort in the indoor environment, and case (O) is four levels higher than case (A) in Panel 5.Next, the fatigue level of panel 8 shown in Fig. 5(e) indicates that the fatigue level is six levels higher at the pre-work point in case (A) than in case (O) and (W). In addition, in the pleasantness of the odor shown in Fig. 5(f), the pleasantness of the odor increased in case (O) and decreased in case (A) from the second to the third subjective evaluation, even though the same odor was sprayed.The same was true for the pleasantness of the airflow in Fig. 5(g), suggesting that the same indoor environment may be perceived as unpleasant on days when the panel was not in good physical or mental condition and was highly fatigued before the experiment.

Experimental Results and Discussion of Physiological Reactions
The subject averages for β/α, α wave content, and β wave content of the occipital (O1 and O2) EEG are shown in Fig. 6, Fig. 7, and Fig. 8, and for heart rate in Fig. 9.The EEG was measured continuously (1000 Hz) during the experiment, and the values averaged every minute are shown.The 0-14 point is task (1), the 15-22 point is relaxation, the 23-24 point is refreshment In case (R) the 15-24 point is relaxation, while in case (T) the 15-24 point is task (2), and the 25-39 point is work (3).In case (L), the values of β/α and β-wave content increased at the start of the refresh state compared to case (R), suggesting that the subjects may have been in an aroused state due to the change in the lighting. In case (A), the values of β/α and β-wave content increased with refreshment, indicating that changing the odor, lighting, and airflow environment may be more effective than the lighting environment alone in maintaining arousal ( Fig. 6 and Fig. 8).In electrocardiograms, heart rate values increased at the start of the refresh state in case (L) and (A) compared to case (R), suggesting that subjects may have been in an aroused state due to the effects of changing the lighting or the odor/illumination/airflow. (Fig. 9)

. E x p e r i m e n t a l r e s u l t s o f w o r k performance
The d2 test was evaluated in terms of achievement and error rates. Fig. 10 and Fig.11 show the achievement and error rates for 8 (case (O)(L)(W)(A)(R)) or 10 (case (T)) d2 tests as work performance.The second and third times of the attainment rate showed results of increased achievement rates in all conditions. This could be attributed to the influence of having the subjects solve

Fig. 5 Correlation between fatigue level and psychological reaction
Sudoku between the second and third sessions of the d2 test (Fig. 10).The results of the comparison between the mean of the first half of the task and the mean of the second half of the task for the achievement rate are shown in Fig. 12. A t-test was performed between condition (R) and the other conditions. A t-test was also performed between the mean of the four d2 test scores in task (1) and the mean of the four d2 test scores in task (2). For achievement rates, there was a significant increase in achievement rates for case (O), (L), (W), and (A) for task (1) and task (3).On the other hand, the achievement rate did not increase significantly for conditions (R) and (W), indicating that the effect of changing environmental factors during the break may have increased the achievement rate (Fig. 12).The the effect size for each condition, calculated with respect to the ratio of the pre and post-half averages of the achievement rate and the error rate with respect to case (R), are shown in Fig. 13.There was no significant difference in the error rate between case (R) and (O), however there was some difficult in the achievement rate, indicating that changing the odor environment may improve work performance (Fig. 13).

Conclusions
This paper investigated the effect of having breaks and of changing the environmental factors during breaks on psychological reactions. Changes in lighting had an effect on the tendency to feel uncomfortable for all panels.Changes in odor and airflow also had an effect, but the results showed that there were large individual differences.Even in the same panel, there were large differences in subsequent psychological reactions depending on the degree of fatigue in the initial stage.Regarding the effects of the presence or absence of breaks between tasks on physiological responses and work performance, the results indicated that changes in lighting, smell, and airflow environment during breaks may increase subjects' arousal level and improve their work accomplishment.This study is funded by Panasonic Corporation.The authors are appreciative of the support provided.

7.Acknowledgement
This study was conducted with the approval of the Ethics Committee of the Graduate School of Engineering, Osaka University.

References
1. Effects of physical activity promotion and breaks in office common space on psychological quantity, human physiology, and intellectual productivity (2nd Report), Proceedings of the Annual Conference of the Japan Society of Air-Conditioning and Hygiene Engineering ,pp.373-376,2019 2. Sa kair i, Y. , Na katsu ka, K. a nd Shimiz u, T.: Development of the Two-Dimensional Mood Scale f or self -monitoring and self -regulation of momentar y mood states, Japnanese Psychological research, 55, pp. 338-349, 2013