The „Next-Generation Classroom" concept demonstrates the everyday benefits that space technology and medical technology can offer: the retrofit kit for rooms is designed to reduce virus density (corona and influenza viruses) and, hence, the risk of infection. This is achieved by a vertical ventilation concept with a low-impulse extraction system on the ceiling.
The coronavirus is not taking a winter break
The risk of being infected by pathogens that are primarily transmitted via the respiratory tract increases in enclosed spaces as the amount of contaminated aerosols and the time spent there rise. If the density of pathogens exceeds a critical threshold, the risk of infection increases. In order to counteract this, the virus load must be reduced over time. This can be done by diluting the air with fresh air (ventilation) or filtered air (room air filter). The joint OHB-HT idea aims to displace and filter potentially contaminated indoor air efficiently and as quickly as possible.
In many areas of public life, several people spend time in the same room over a prolonged period of time. The cold season that is now beginning not only entails a heightened risk of influenza but also makes constant or effective ventilation difficult (for energy-saving and medical reasons). Previous concepts, such as ventilation or fans with a non-directional airflow, bear the risk of uncontrolled mixing occurring in the air. This can lead to a situation in which, depending on the virus load released by the source and the length of time spent in the room, there is still a high risk of infection.
The OHB-HT concept applies space expertise and proven practices from medical technology
Dr. Axel Müller works in OHB’s Cleanliness department. Put simply, he ensures that satellite components do not pick up any contamination (of a chemical, particulate or biological type) and that heat influences do not interfere with high-precision measurements. The means of choice for achieving this is an optimised air flow that eliminates the disturbing influence of heat and contamination sources on the component to be protected.
This was exactly what inspired Dr. Müller to design equipment for classrooms, doctors’ surgeries and other rooms capable of improving the safety of the people in them: “The objective is to quickly filter air that is potentially virus-contaminated in a targeted manner and to prevent any uncontrolled mixing of the air in the room.”
Uplift: The rising air stream protects people in the vicinity
To achieve this, three factors are crucial: The gentle, slow-moving filtered airflow (also known as a “low-impulse airflow”) is introduced at the bottom of the room and, due to the human-induced uplifting effect, flows upwards past the people in the room towards the ceiling. A directed undisturbed (i.e. low-turbulence) air flow arises between the person’s head as the source of aerosols and the extraction device on the ceiling. This effect is aided by the fact that exhaled air is warmer than the ambient air. In addition, a strong uplift is generated due to the layers of air heated by the body (convection). “In the OHB-HT concept, the heated, rising air and the filtered air introduced move upwards simultaneously. This significantly reduces the horizontal distribution of air to the adjacent person, creating a protective wall of ultrapure air, so to speak,” explains Dr. Müller.
With the HT Group for more than 25 years, Thomas Fritsch is responsible for the construction of operating theatres and high-security laboratories: “The method we have chosen is the result of the HT Group’s decades of experience in filter and ventilation systems used in hygiene areas to produce low-germ air.”
Fitted as a retrofit kit in the autumn and winter in particular, this cost-efficient and effective solution devised in a team and implemented in a partnership between OHB System AG, the HT Group and DASTEX could make it possible to continue using closed rooms. Major structural conversion measures are not necessary for the installation. The “Next-Generation Classroom” is currently being tested at the Institute of Aerodynamics and Flow Technology in Göttingen, which has a large number of experimental and numerical methods for measuring and simulating particle and aerosol propagation.
Measurements at the DLR Institute confirm the OHB-HT concept
The Institute of Aerodynamics and Flow Technology at the German Aerospace Center (DLR) in Göttingen can draw on more than ten years of expertise in ventilation systems, particularly in vehicles. Dr. Andreas Westhoff oversaw the first multiday phase of the measurement campaign: “The examination of the OHB-HT room ventilation system has shown that the tested prototype can be used to create a stable flow leading from the human body directly to the extraction unit. The uplifting effect generated by the people in the room supports this effect. This reduces the uncontrolled spread of virus- and bacteria-contaminated aerosols from exhaled air. In addition, the virus-contaminated air is effectively fed into the filter system.”
“The measurements were carried out using heated, breathing human models who may also emit aerosols, which were simulated by using CO2 as a tracer gas during the measurements. A classroom, a doctor’s waiting room, a catering area and cinema seating were simulated. The proportion of fresh air in the facial area and the removal of used air were measured in the various constellations and show that the risk to the adjacent person was greatly reduced,” reports Axel Müller.
The “Next-Generation Classroom” demonstrator will be undergoing further testing in Göttingen in the coming weeks. At the same time, the syndicate is planning to perform a practical test in a school or restaurant.
As a member of the Management Board of OHB SE, Klaus Hofmann is also responsible for the OHB “Optics & Science” space centre in Oberpfaffenhofen near Munich. He supervises and monitors the projects in which OHB is seeking to make targeted use of processes and procedures from the space industry in responding to the pandemic: “It is well known that space projects simplify people’s everyday lives. Putting our space expertise to good use in the fight against the coronavirus and thus mitigating its effects on our everyday lives by avoiding infections is a prime example of the successful transfer of space technology for the direct benefit of society.”
How the OHB-HT concept works
A low-impulse ventilation system is installed in the room and extracts and filters the potentially virus-contaminated exhaled air, feeding it back into the room. This requires a fan, a HEPA filter unit (ultra-fine particle filter) and an air hose made of the type of textile used in the space industry. Optional features include temperature stabilisation for the summer months through the integration of cold registers and LED strips on the textile for broad-based energy-optimised illumination.
HEPA filters and textile hoses are recyclable and can be replaced after defined cycles and reprocessed by professional cleaning or disinfection.
The OHB-HT concept not only targets the coronavirus but is also designed to optimise air quality to reduce contamination by pollen, bacteria, fungi and fine dust.
Working together against Corona
As space systems specialist, OHB System AG forms the backbone of the “Next-Generation Classroom” project by coordinating implementation as well as simulation, design and experimental verification. The other partners are networked via various OHB projects: With its expertise in designing and constructing ventilation systems for laboratories, hospital wards and operating theaters, the HT Group has extensive practical skills and the human resources required for implementing the OHB-HT system on site. A supplier of clean room textiles and a specialist in textile design and the associated production chain, DASTEX has already implemented clean room enclosures, air distribution systems and the like with and for OHB.
Further information on the measurements at the DLR Institute of Aerodynamics and Flow Technology can be found in the DLR press release of 3 November 2020.
Media inquiries should be directed to Ms Yvonne Brühmann, who is the contact person at HT Group.