Press Release
March 8, 2021
Daiichi Kosho Co., Ltd.
Ventilation survey of karaoke room Big Echo
■ The air in the karaoke room is exchanged with outside air at a fast rate
■ Particles floating in the room decrease rapidly
Proven to have much higher ventilation performance compared to typical homes and offices
Dai-ichi Kosho Co., Ltd. is a general incorporated association Clean Air *1 (hereinafter referred to as "Clean Air") and Professor Tomoaki Okuda of the Faculty of Science and Technology, Keio University (hereinafter referred to as Keio University), conducted a survey of the ventilation situation at the Big Echo Hamamatsucho Ekimae store. As a result, we were able to confirm that the ventilation performance of Big Echo is very high, that air is replaced by outside air at a fast rate, and that particles suspended in the room are reduced at a fast rate.
Installation of measuring equipment (Room 818)
CO2 spraying with dry ice (Room 818)
1. Background
According to government announcements and media reports, "karaoke parlors are enclosed spaces with poor ventilation", and many karaoke users continue to refrain from using them. In the prevention of virus infection, "ventilation" is an effective means of physically eliminating viruses floating in the air.
Therefore, for the purpose of scientifically verifying the ventilation condition of karaoke rooms, we investigated the ventilation system at Big Echo *2 I did.
2. Survey Overview
On December 5, 2020, under the supervision of Professor Tomoaki Okuda of the Department of Applied Chemistry, Faculty of Science and Technology, Keio University, we conducted a survey on the ventilation status of the following two types of rooms (818 rooms: maximum capacity of 29 people/room volume 64.1㎥, 823 rooms: maximum capacity of 10 people/room volume 31.1㎥, and 820 rooms: maximum capacity of 5 people/room volume 13.3㎥) of the Big Echo Hamamatsucho Ekimae store. *2
- ①"Indoor CO 2 Concentration Measurement
Investigate the ventilation speed (outside air intake rate) in the room. Using a dry ice generator, CO 2 Generate a large amount of . Ventilation and air conditioning equipment are put into operation to see the attenuation of CO2 concentrations. - ②"Indoor particle concentration measurement"
The number of ventilations in the room (the rate of reduction of particles) was investigated. Considering that the virus is suspended in space in a state attached to the particles, a smoke generator is used to generate a large number of smoke particles in the room. Ventilation and air conditioning equipment are put into operation to see the attenuation of airborne particle concentrations.
3. Survey results
- ①The air in the room ⇒ "indoor CO2 concentration measurement" replaces the outside air at a fast rate
The time it takes for all the air in the room to be replaced by the outside air *3 818 rooms/approx. 10 minutes 42 seconds (ventilation frequency: 5.6 times/1 h), 823 rooms/approx. 8 minutes/27 seconds (ventilation frequency: 7.1 times/1 h), and 820 rooms/approx. 7 minutes/35 seconds (ventilation frequency: 7.9 times/1 h). This is a faster ventilation speed than a typical home or office. - ②"Indoor particle concentration measurement" ⇒ particles suspended in the room decrease at a fast rate
The average amount of time particles are suspended in the room *4 818 rooms for about 1 minute, 823 rooms for about 3 minutes, and 820 rooms for about 28 seconds. In addition, the particles decreased at a faster rate than the time it took to replace the outside air, indicating that the filters installed in the air conditioning piping system of the store and the air conditioner in each room were functioning effectively.
The risk of aerosol infection (droplet nucleus infection), which is thought to occur when particles containing high concentrations of virus stay in the space, is considered to be lower than that of ordinary homes and general offices, where ventilation rates are slower. *5 - ■By controlling the number of people entering the room, it is possible to maintain good ventilation conditions that do not hit the enclosed space.
When referring to ventilation conditions, it is extremely important to consider 'how many people are in the space.' Even if the ventilation rate meets the standards, the risk of infection increases as the number of people in the space grows.
Therefore, the survey summary (1) "Indoor CO 2 Using the measured values of ventilation frequency obtained from 'concentration measurement,' the Ministry of Health, Labour and Welfare indicates CO 2 Estimation of the maximum number of people entering each room that simultaneously satisfies a concentration of 1,500 ppm (School Health Act) and a ventilation volume of 30㎥/1h per person (standard of the Society of Air Conditioning and Sanitary Engineers). *4 Have. As a result, room 818 has 11 people (maximum capacity of 29 people), room 823 has 6 people (maximum capacity of 10 people), and room 820 has 3 people (maximum capacity of 5 people).
Big Echo Hamamatsucho Station Ventilation Survey Results
| Experimental conditions | CO2 Concentration measurement results | Particle concentration measurement results | CO2 Utilizing concentration measurement results Simulation | ||||
|---|---|---|---|---|---|---|---|
| Room | maximum Capacity | Room volume | Ventilation rate [1] (Actual value) | The air in the room is different from the outside air. Time to switch places[2] | Ventilation rate [3] (Actual value) | Particles in the guest room Time spent floating[2] | Maximum number of people allowed in the room (30㎥/h× person)[4] |
| 818 | 29 people | 64.1㎥ | 5.6 times/hour | Approximately 10 minutes and 42 seconds | 56.5 times/hour | Approximately 1 minute | 11 people (32.6 m3/h x person) |
| 823 | 10 people | 31.1㎥ | 7.1 session/hour | Approximately 8 minutes and 27 seconds | 20.5 times/hour | Approximately 3 minutes | 6 people (36.8 m3/h x person) |
| 820 | 5 people | 13.3㎥ | 7.9 times/hour | Approximately 7 minutes and 35 seconds | 129.7 times/hour | Approximately 28 seconds | 3 people (35.0 m3/h x person) |
"supplement"
- (1)The term 'ventilation rate,' that is, 'the time it takes for an equivalent volume of outdoor air to be supplied to the target space,' is expressed as 'the time it takes for all the air in the room to be replaced with outdoor air.' There are reports (Menzies et al. (2000), Bloch et al. (1985)) indicating a significant correlation between ventilation rates of two or fewer times per hour and the spread of tuberculosis and measles. A study of a restaurant in Guangzhou where a COVID-19 cluster occurred (Li et al. (2020)) reported that the ventilation rate inside the restaurant was extremely low, at 0.56-0.77 times per hour.
- (2)Calculated by JCAA based on actual measurements.
- (3)The number of ventilations referred to here refers to the number of times air containing particles is replaced with clean (non-particle-free) air, obtained by combining the amount of outside air intake and the particle reduction effect by the filter.
- (4)The Ministry of Health, Labour and Welfare has announced that if the ventilation volume meets the required ventilation volume of '30 cubic meters per hour per person,' it does not fall under the category of 'poorly ventilated spaces.'
4. Clean Air Perspective
From the results of this survey, it became clear that the ventilation performance of the karaoke room at the Big Echo Hamamatsucho Ekimae store is high. Furthermore, by controlling the number of people entering the room, it was found that "ventilation volume of 30 cubic meters per hour or more per person" was maintained, and good ventilation conditions could be maintained that do not fall into the "poorly ventilated space" or "enclosed space" indicated by the Ministry of Health, Labor and Welfare. Good ventilation reduces the risk of new coronavirus infections.
However, in order to prevent the spread of the novel coronavirus, it is necessary to combine multiple measures in addition to ventilation strategies. Moving forward, it is expected that, in addition to ensuring proper ventilation, scientifically verified and considered measures addressing droplet and contact transmission will be implemented to provide safe environments.
5. Future plans
At Big Echo, we will continue to thoroughly implement infection prevention measures such as cleaning and sterilization, limiting the number of users, and ensuring that employees wear masks, wash their hands, and check their health so that they can use our stores safely and securely.
- *1 Clean Air is a medical organization that raises awareness of respiratory diseases and develops prevention and treatment methods for respiratory diseases.
- *This time, we conducted a survey at the Hamamatsucho Station Front Store, but in accordance with the Building Standards Act, all Big Echo locations nationwide are equipped with a ventilation system equivalent to that of the Hamamatsucho Station Front Store.
- *The number of air changes, namely 'the time it takes for an equivalent volume of outdoor air to be supplied to the target space,' is described as 'the time it takes for all the air in the room to be replaced.'
In addition, the value is calculated for clean air from the actual measured value. - *4 Clean air is calculated from the actual measured value.
- *5 Regarding the time it takes for all the air in a room to be replaced with outside air, the Building Standards Act requires that it be shorter than 2 hours (ventilation frequency 0.5 times/h or more). A typical office (5 m2 per person occupying a ceiling height of 2.8 m) requires that it be shorter than about 30 minutes according to the Building Management Act.
(30㎥/h per person)