In the COVID-19 pandemic, it became clear that adequate ventilation is the key engineering measure to reduce the spread of respiratory viruses. REHVA experts have now collected available evidence and developed a health-based ventilation design method to mitigate the infection risk in indoor spaces. The current ventilation design based on the existing indoor climate standards EN 16798-1:2019 and ISO 17772-1:2017 has been limited to the use of ventilation criteria based on the perceived air quality (odours) or specific pollutants and has not considered respiratory disease transmission.
The infection risk-based ventilation design method proposed in this document provides new target ventilation rates and is intended to complement existing ventilation design methods in non-residential buildings, excluding healthcare and industrial buildings. It is proposed that the target ventilation rates be applied in the design of new buildings and renovations so that the highest of health- and comfort-based ventilation rates is used as the design capacity of the ventilation system. Health-based ventilation rates may be higher than comfort ventilation rates and are required only during epidemic periods. In normal conditions – that is, outside of epidemic periods – a demand-controlled operation is recommended to comply with comfort-based values and to optimise the energy used for ventilation.
August 2023 update addresses some changes in the guidance how to calculate the point source ventilation effectiveness. These changes are in the explanations of Equations 5 and 6, and in the calculation example in Appendix 3. It is noted that ventilation effectiveness should be calculated from average concentration at the breathing level, and if local air quality index values are used, the reciprocal values are to be summed as shown in new Equation 23.