UVC Air Purifier Calculator

Project name:

Room volume

Floor space:

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m²

Ceiling height:

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Room volume:

m³

Room usage

Occupancy time without fresh air ventilation:

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hours

Occupancy (number of persons):

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Room type

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*More information at About the calculator

ABOUT THE CALCULATOR

^{The UVC air purifier calculator provides instructions on which device to use and which amount is recommended for a room. The calculation is based on the scenario that exactly one person is infected in the room and stays with other people in the room for a period defined by the tool user. It is assumed that the room air is 100% virus-free at time 0.

Recommendation for the number of devices: The recommendation is based on the one hand on the desired air exchange rate and on the other hand on the number of people in the room and depends on the use of the room. The air exchange rate is defined as the total air throughput of the devices divided by the room volume.

- We recommend an air exchange rate of at least 2.5 (standard)

- The risk of infection is increased in rooms that are visited by a large number of different people within a day (meeting rooms, waiting rooms, etc.) and we recommend an air exchange rate of 4 (increased safety).

- In addition, we recommend a minimum air flow rate of 25m³ / h and person, regardless of the size of the room. The recommendation is based on Table C.4 in EN 16798-2 Overall Energy Performance of Buildings - Ventilation of Buildings. Our recommendation is based on the ventilation rate for an expectation of category II air quality.

- The Federal Environment Agency recommends an air change rate of 6 (school) for schools regardless of the number of people in the classroom.

The calculation of the virus concentration and the likelihood of infection follows the work "Predicted infection risk for aerosol transmission of SARS-COV-2" by Prof. Dr.-Ing. M. Kriegel et al, Hermann Ritschel Institute, Technical University Berlin.

Preprint: https://doi.org/10.1101/2020.10.08.20209106

The virus quantum model was taken from "Estimation of airborne viral emission": Quanta emission rate of SARS-CoV-2 for infection risk assessment "by G. Buonanno et al, University of Cassino and Südlazio. The following modeling input parameters were used:

- cv 5.0E + 08 (viral load in sputum, viral RNA copies / ml)

- ci 0.05 (ratio between the infectious quantum and the infectious dose, expressed in viral RNA copies)

- Qb depending on the activity (tidal volume) - standard value 0.54 m³ / h

Please note that cv varies greatly depending on the individual and the time of infection. The probability of infection varies greatly depending on the input parameters cv, ci and Qb. However, the relative reduction in the risk of infection by an air purifier does not change as much.

Environment International, Volume 141, 2020, 105794, ISSN 0160-4120, https://doi.org/10.1016/j.envint.2020.105794 .

The natural virus decay was calculated for 20 ° C, RH 30% and UV index 0 with the computer of the Department of Homeland Security and determined with D50 = 2.72h.

https://www.dhs.gov/science-and-technology/sars-airborne-calculator

The calculator is based on the following publication:

P. Dabish et al, "The influence of temperature, humidity and simulated sunlight on the infectivity of SARS-CoV-2 in aerosols", Aerosol Science and Technology, Volume 55, 2021 - issue 2

The air sanitizers are believed to have a virus inactivation rate of 99.9%.

A natural air change ACH of 0.35 is assumed for the reference case.}

GLOSSARY

Air flow rate / Clear air delivery rate (CADR): The clean air flow rate is the volume of air that flows through the device (s) per hour. A higher CADR leads to a lower virus concentration.

Air change rate: The air change rate (abbreviated ACH = Air Change Rate) is equal to the total CADR of the devices in the room divided by the room volume. A higher air exchange rate leads to a lower virus concentration.