AIVC - Air Infiltration and Ventilation Centre

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Are COVID-19 recommendations of REHVA and ASHRAE similar?

REHVA and ASHRAE agree on their main recommendations, but there are some slight differences in the specifics.


Can a measured CO2 concentration show a building is SARS-CoV-2 safe?

An indoor CO2 concentration is commonly used as an indicator of the ventilation rate in indoor spaces, albeit with great uncertainty. Its concentration depends on the number, demographics, and activities of occupants, the outdoor air supply rate, mixing, inter-zonal airflow, the air renewal rate, and the outdoor concentration.


Can portable air cleaners prevent the spread of COVID-19 indoors?

There are various measures to reduce the risk of exposure to the virus that causes COVID-19 from spreading indoors and generally fall into three main categories: source control, ventilation control, and removal control. Source control means reducing the number of people in the enclosed space (1). This enables social distancing, which reduces the number of infected people (if there is an infected person in the enclosed space) and provides more outdoor air per person. Increased ventilation dilutes the infectious aerosols produced by infectious human pathogens.

20 November 2020, Webinar – COVID-19 Ventilation related guidance by ASHRAE and REHVA

Ventilation is recognized as a major element in strategies for minimizing the risk of COVID infection. REHVA and ASHRAE have developed guidelines taking existing evidence of long-range aerosol based transmission into account including the importance of ventilation.


This webinar presented the guidelines by REHVA and ASHRAE and also had a closer look to the similarities and differences in both guidelines.