TECHNOLOGY AND INNOVATION CENTER

Awareness for the importance of “epidemic mitigation through air conditioning” has significantly increased during the COVID-19 pandemic. As a company specializing in air conditioning, Daikin has been developing measures for using air conditioning to reduce the spread of infectious diseases and allergies. Kiyoshi Kuroi is the senior engineer at Daikin’s Technology and Innovation Center (TIC) and stands at the forefront of using air conditioning for epidemic mitigation. Recently he talked to us about measures currently under consideration.

-Streamer technology is a technology developed by Daikin that has been shown in research to be effective in inactivating SARS-CoV-2, the virus that causes COVID-19. To find out more about Daikin's unique Streamer technology and its beneficial features, we asked Kiyoshi Kuroi, Senior Engineer and Leader for the IAQ Technologies Group.

The most distinctive feature of Streamer technology is its ability to stably generate electrons with high power. There may be a way, for example, to make discharge for instantaneous power higher than that of Streamer discharge, but for commercialization the key word is "stably." Then there is the uniqueness of the mechanism for using the technology. Other methods generate active particles that are released outside the machine to hit the virus, but the Streamer technology hits the virus with the active species collected inside the machine. Therefore, the energy is concentrated, and the virus can be efficiently inactivated.

-In December 2019, SARS-CoV-2, the virus responsible for the COVID-19 pandemic, first surfaced, and as COVID-19 began spreading worldwide, Daikin worked quickly to verify the effectiveness of its Streamer technology for epidemic mitigation. In July 2020, the company confirmed the inactivation effect of its Streamer technology on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the mouse hepatitis virus strain A59 (MHV-A59). After one hour, Streamer irradiation inactivated 93.7% of SARS-CoV-2. More than 99.8% of the virus was inactivated after two hours of irradiation, and more than 99.9% after three hours*.

Streamer technology has subsequently been verified to be effective in the inactivation of each mutant strain causing COVID-19.In January 2022, this inactivating effect was confirmed for four mutant strains, including the Delta strain. The inactivating effect for the Omicron strain, which emerged in Japan at the end of November 2021, was confirmed in February 2022.

Kuroi: Even before the outbreak of the COVID-19 pandemic, Daikin had been conducting experiments on the various effects of Streamer technology at universities and test laboratories in Japan and overseas that confirmed the ability of Streamer to inhibit and inactivate various viruses and bacteria.

-As Mr. Kuroi stated, Streamer technology has undergone a wide range of demonstrations, and the following areas have been proven to be effective (as of March 2022).

■Coronaviruses
・July 16, 2020…SARS-CoV-2 / Okayama University of Science
・June 25, 2021…Alpha strain / Osaka University
・July 1, 2021…Beta and Gamma strains / Osaka University
・August 27, 2021…Delta strain / Osaka University
・January 2022…Omicron strain / Osaka University

・April 2012…RS virus / Wakayama Medical University
・September 14, 2009…Type A H1N1/National Institute of Hygiene and Epidemiology, Vietnam
・April 16, 2009…Type A H5N1/National Institute of Hygiene and Epidemiology, Vietnam
・July 31, 2009…Type A H1N1/Kitasato Center for Environmental Science

■Bacteria
・March 8, 2010…Mycobacterium tuberculosis, BCG mutant strain / Kitasato Center for Environmental Science
・February 15, 2010…Mycobacterium tuberculosis, clinical strains / The Jikei University School of Medicine
・July 31, 2009…Staphylococcus aureus / Japan Food Research Laboratories, Inc.

■Mold
・September 28, 2004…Black mold /Japan Food Research Laboratories, Inc.

■Allergens
・September 14, 2004…Cedar pollen Cryj-1 / Wakayama Medical University
・September 14, 2009…Kona Leopard Mite rDerfII / Wakayama Medical University
・December 17, 2004 July 7, 2005…Pollen, mold, and mites / Wakayama Medical University
・July 7, 2005…Pollen, mold, and mites / Wakayama Medical University

■Toxic Substances
・Nov. 2005…Adjuvant: Diesel exhaust particulates (DEP) /Yamagata University
・December 8, 2006…Adjuvant: Volatile organic compounds (VOC) / Tohoku Bunka Gakuen University
・November 2005…Adjuvant suppression effect / National Institute for Environmental Studies, Wakayama Medical University

■Water Sterilization
・July 5, 2010…Legionella / The Jikei University School of Medicine
・April 12, 2010…Pseudomonas aeruginosa/Japan Food Research Laboratories
・April 12, 2010…Staphylococcus aureus / Japan Food Research Laboratories, Inc.
・April 12, 2010…E. coli / Japan Food Research Laboratories, Inc.

-The next topic in our discussion of air conditioning and epidemic mitigation involves high efficiency particulate air (HEPA) filters. Mr. Kuroi provided details on these high-performance air filters and the technology that Daikin has developed for them.

Kuroi: I mentioned earlier that HEPA filters were used in cleanrooms. HEPA filters are precision filters that can remove 99.97% of the fine particles floating in the air. At Daikin, we are developing epidemic mitigation technology that utilizes this high performance in epidemic mitigation to collect and inactivate viruses.

-Daikin launched an air purifier equipped with an "antiviral HEPA filter" in December 2020. With the ability to enhance ventilation functions in commercial facilities where the 3Cs (i.e., closed spaces, crowds and close-contact situations) are a concern due to the COVID-19 pandemic, Daikin is quickly responding to the needs of the times.
In April 2021, "UV Streamer Air Purifier" was launched. In addition to the "antibacterial HEPA filter," this purifier is equipped with the aforementioned Streamer technology and "UVC LED," which irradiates deep ultraviolet rays, to suppress viruses by more than 99% in 30 minutes and bacteria about 10 times faster than conventional Streamer air purifiers. The technologies that engineers like Mr. Kuroi research on a daily basis are quickly commercialized to meet the needs of the times and play a role in air conditioning and epidemic mitigation.

-Daikin also contributes to air conditioning and epidemic mitigation at medical facilities. A negative pressure device is a device that controls airflow in a certain direction by creating a low atmospheric, “negative pressure” state to prevent the spread of air mixed with viruses that have the potential for airborne or aerosol transmission. When installed in a hospital or examination room, it can prevent the spread of viruses emitted by patients and the spread of infection.
Preventing nosocomial infections has been a major issue in the medical field during the COVID-19 pandemic, and there has an urgent need for negative pressure devices.

-Based on the HEPA technology introduced earlier, a Daikin Group company commercialized the product in just one month, launching two negative pressure devices in May 2021. In August of the same year, it launched a foldable negative pressure booth, which is used in small clinics and facilities for the elderly that do not have isolated areas.
In addition to negative pressure devices, Daikin's speedy development during the COVID-19 pandemic has continued to bring a variety of products and services to the world.

・Expanded lineup of air conditioners with ventilation functions
・Added new product lineup that can be retrofitted to the "Heat Reclaim Ventilator," a total heat exchanger unit
・Addressed customer air and ventilation concerns via web-based and telephone consultations
・Released the web content "Expert Ventilation Methods," which won the Grand Prix Prize, the highest award, for the PR Award Grand Prix

Kuroi: A total heat exchanger is a device that allows efficient ventilation while maintaining energy efficiency at a comfortable indoor temperature and humidity level. Because of COVID-19, stores, schools, and other facilities where people gather open their windows and doors for ventilation, even in the winter when it's still cold. Having a total heat exchanger means that you can ventilate to maintain a comfortable temperature and save energy. What's more, our new Heat Reclaim Ventilator can be easily retrofitted in interior walls, ceilings, and under the eaves of buildings. Originally, total heat exchangers were embedded in ceilings and could not be installed later, depending on lighting, air conditioning, or duct piping.
But with the new series, we now have a choice of installation locations, including a type that can be suspended from the ceiling, a type that can be installed outdoors, and an exposed type suitable for small spaces. I think these devices are perfect for schools and stores that have ventilation problems.

Because of the COVID-19 pandemic, a speedy response has been essential for air conditioning and epidemic mitigation. Daikin has several Daikin Group companies that specialize in this kind of speedy development, and the distributors who sell our products also respond quickly. We have a system in place to quickly scoop up urgent needs from the field and proceed quickly from development to sales. No matter how good a product is researched and developed, it is meaningless if it is not used. I believe that Daikin's ability to respond quickly to "problems" is a major strength in contributing to air conditioning and epidemic mitigation.

-Daikin is a "company that provides solutions through air” and continues to work on various types of air conditioning and epidemic mitigation.What kind of future do the engineers at the forefront of research and development envision in the lengthy COVID-19 pandemic?

Kuroi: I think we need to reevaluate and change the conventional methods of air conditioning and ventilation. With so many people suffering from the COVID-19 pandemic, we need to pursue "what can be done with air conditioning," "what is proper ventilation," and "effective air purification," through joint research with university professors as we work to create a new way of doing things. To this end, I believe that Daikin has a social responsibility as an air conditioning manufacturer.

There are two things to consider in terms of epidemic mitigation. One is to reduce the transmissibility of viruses. First, I want to reduce virus transmissibility by using appropriate ventilation methods to dispose of air containing viruses, collect the viruses in high-performance filters such as HEPA filters, and disinfect them with Streamer and UV technologies. In other words, we want to defeat them and hope to achieve this by reducing the virus concentration in the air through these three steps of disposing, collecting, and disinfecting.
Second, I want to boost the natural defenses of people. Humidification enhances the immune system by helping the mucous membranes of the nose and throat to function normally and by creating a comfortable environment where people can get sufficient rest. Our aim is to create spaces where people can do that.

Until now, air conditioning has been thought of as "defense" in the sense of removing harmful substances and reducing the negative conditions to zero. Now, we are working to change the concept by adding good attributes to the air to achieve positive conditions. For example, rather than simply lowering the temperature when it is hot or raising it when it is cold, there could be a mechanism to release air in which effective substances have been added or the temperature could be controlled to make the air healthier. We are taking on challenges to develop new technologies to create healthier air.
I have allergies including atopic dermatitis and asthma, so when I visit my parent’s home the change in air and environment can worsen my health. Because of that, I have firsthand experience of the relationship between air quality and health, and it has come in handy here (laughs). I am blessed with the opportunity to solve my own problems through my work, and I want to go on the offensive with "healthy air" in addition to taking a defensive stance.

-Daikin is going beyond just heating and cooling. As Mr. Kuroi tells us, the functions required of air conditioning are becoming more diverse, and Daikin continues to be a leader through its rapid and multifaceted development relating to air conditioning and epidemic mitigation.