Daikin and NEC successfully demonstrate effectiveness of temperature stimulation for improving intellectual productivity in the workplace

Osaka & Tokyo, Japan, July 25, 2018 - Daikin Industries, Ltd. (Daikin; TSE: 6367) and NEC Corporation (NEC; TSE: 6701) today announced the successful completion of verification tests demonstrating that temperature stimulation by air conditioning is particularly effective for improving intellectual productivity in the workplace. These tests were performed as part of joint research activities aimed at realizing air-and-room environments for enhancement of intellectual productivity that have been carried out by Daikin and NEC since 2016. The results also revealed that early application of stimuli when signs of drowsiness first begin to appear is effective in maintaining arousal levels (*1).

Description of verification tests

Larger viewFigure 1: Yerkes-Dodson's law

Maintaining a proper arousal level without evoking drowsiness is said to be important for boosting intellectual productivity (Fig. 1 (*2)). To investigate the best method and timing for application of environmental stimuli to maintain arousal levels, stimuli comprised of air conditioning (temperature), lighting (illuminance), and aroma (fragrance) were applied to subjects while periodically measuring their arousal level to verify changes.

1. Verification method

Verification tests were performed to confirm changes in the arousal level of subjects when environmental conditions were changed at predetermined times. Subjects were assigned a task that would render them drowsy (i.e., mental addition of two-digit numbers) and asked to report every five minutes how drowsy they felt on the basis of a five-point scale while a web camera was used to estimate their drowsiness (Fig. 2).

Below are descriptions of the four sets of environmental conditions under which these verification tests were performed.

Condition 1: Room temperature set at a constant 27℃; no aroma; illuminance of 700lx
(No changes made to the environment)

Condition 2: Room temperature set at 27℃ → 24℃ → 27℃; no aroma; illuminance of 700lx
(Room temperature changed at the beginning of the second set and the beginning of the fifth set)

Condition 3: Room temperature set at a constant 27℃; no aroma; illuminance of 150lx → 1500lx → 150lx
(Illuminance changed at the beginning of the second set and the beginning of the fifth set)

Condition 4: Room temperature set at a constant 27℃; no aroma → aroma → no aroma; illuminance of 700lx
(Aroma diffused for a 30-minute period from the beginning of the second set up until the fifth set)

Figure 2: Verification test protocol

2. Verification results

With temperature stimulation by air conditioning, the average arousal level on a five-point scale was found to be higher by a maximum of approximately two points in comparison with cases in which no environmental changes were made, and it was also determined that proper arousal level could be maintained for more than 45 minutes. As for stimulation by lighting and aroma, it was confirmed that the arousal level was higher by a maximum of approximately 0.5 points in comparison with cases in which no environmental changes were made (Fig. 3).

Figure 3: Amount of change in arousal level for each stimulus applied (Comparison with cases in which no environmental changes were made)

It was also determined that effects for maintaining proper arousal level could be increased by applying stimuli when signs of drowsiness were detected rather than waiting until the subject was already drowsy, and that these effects could be further elevated by changing the manner in which stimuli such as temperature, lighting, and aroma are applied or by combining them.

Future field trials

On the basis of these verification tests, Daikin and NEC have built a prototype control system for detecting signs of drowsiness from the degree of eye opening and applying a stimulus combining air conditioning and lighting. From July, 2018, field trials will begin at offices being used at Daikin (40 square meters) and at NEC (200 square meters) for verification purposes. Through these field trials, arousal level data will be acquired as employees work and environmental control of air conditioning and lighting will be conducted.

Larger viewFigure 4: Example of system configuration for field trials

Utilizing not only air- and room-related technologies but also AI and IoT technologies, Daikin and NEC have been conducting joint research since October 2016 with the aim of developing solutions that deliver new value through the realization of air-and-room environments for enhancement of intellectual productivity in the workplace. Going forward, Daikin and NEC will seek out other partners with whom they can conduct additional field trials as well as engage in efforts focused on new value creation.

New technologies used in these verification tests

1)Technology for controlling arousal level by temperature stimulation (Daikin)
Although it has long been said that people become drowsy when they feel too comfortable and that exposure to cool air from outside can reduce drowsiness, the mechanisms behind these phenomena were not evident, and it was unclear what methods could be used to effectively maintain both proper arousal level and comfort.

In these verification tests, focus was placed on the fact that the autonomic nervous function involved in thermoregulation is also related to arousal and drowsiness, thereby making it possible to verify that arousal levels can be controlled by the manner in which temperature stimulation is applied. It is already known that the human body has a thermoregulation mechanism with which blood vessels contract, the sympathetic nerve is stimulated, and the arousal level rises to prevent a decrease in body temperature when the body shifts from a thermally neutral state to a cool state. This led Daikin to examine and verify an environmental control algorithm concentrated on maintaining proper arousal levels without compromising comfort. Results showed that proper arousal levels could be maintained by creating slightly cooler conditions as soon as signs of drowsiness were observed and that comfort could be maintained by returning conditions to their original state within a short period of time. Daikin also confirmed that the arousal state could be maintained for a longer period of time with temperature stimulation than with stimulation applied using lighting and/or aroma.
2)Arousal level estimation technology (NEC)
In the past, arousal levels were estimated by extracting eyelid movement from videos in which a subject's face was recorded to determine the duration of his/her eyes closure and the number of times he/she blinked. While this method made it possible to accurately estimate arousal levels, it also required the use of expensive PCs capable of high-speed image processing of more than 15 frames per second to capture individual blinks, for which the average duration is several 100 milliseconds.

NEC performed these tests to verify whether or not it would be possible to accurately estimate arousal level using facial video data with a low frame rate by paying careful attention to slower movement "supporting the weight of the eyelid" (eyelid variability) as a sign of a decrease in arousal level. Results confirmed that the level of decline in arousal level (*3) could be estimated from videos with a frame rate of five frames per second—approximately one-third the conventional frame rate—with the same accuracy by regarding two different types of eyelid variability (time variability and left-right discrepancy) as signs of a decline in arousal level. This means it is possible to accurately estimate decreases in arousal level even using an inexpensive microcomputer with low processing capacity.

Larger viewFigure 5: Comparison of eyelid variability

In addition, NEC announced its arousal level estimation technology at the 40th International Conference of the IEEE Engineering in Medicine and Biology Society, the flagship international conference of the medical engineering field, which was held this year in Honolulu from July 17 (Tue.) to 21 (Sat.). (https://embc.embs.org/2018/)

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*1)Arousal level
This is an indicator of the level of excitement in the brain (levels range from states of relaxation to tension). In the automotive industry, research is being conducted on how methods for determining eye movement can be utilized for technologies designed to automatically detect dozing drivers.
*2)Yerkes-Dodson's law
This is a law in the field of psychology discovered in 1908 by psychologists Robert Mearns Yerkes and John Dillingham Dodson that states there is an inverted U relation between arousal level and performance.
*3)Level of decline in arousal level
Three third-party individuals who underwent training were assigned the task of observing facial expressions and rating the arousal level of each subject on a five-point scale that ranged from not drowsy to very drowsy.

Arousal level estimation technology
https://www.nec.com/en/global/rd/technologies/201801/index.html

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