Diff for "CovidVentilation"

Differences between revisions 4 and 5

Some thoughts and numbers on ventilation during COVID

When someone sneezes, coughs or sings, they create aerosols that linger in the air for hours.
The purpose of ventilation is to carry those droplets out of the building before someone breathes them in.
The time to do that needs to be small compared to the service duration to be useful.
Assuming that we want the air changed 5 times per hour and the church is 20 metres wide, this means an average air flow of 100m/hour or 0.1km/hr
So the fraction of the wall that needs to be open is 0.1 divided by the outside wind speed in km/hr.
If the average height is 5 metres, then the required opening can be calculated in cm as 500 times that, 50/(wind speed in km/hr). Five cm for a 10kph wind.

Ventilating complaints about air standards.pdf
Virus is airborne; ventilation is key.
Purifier airflow rates of 3 litres of air per second per person are needed.
- This comes to 10.8 cubic metres per hour per person.
- Samsung AX7500K Air Purifier $999 is rated as CADR 701m³/hr (Clean Air Delivery Rate)
A fallback ventilated system (for a naturally ventilated building) comes into operation when the detected levels of CO2 in the air rise above about 800 parts per million, so it could reliably improve air quality.

-  ⇤ ← Revision 4 as of 2021-07-30 06:34:35 → 
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  Editor: DavidMorgan
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+   ← Revision 5 as of 2021-08-01 08:00:52 → ⇥
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  Editor: DavidMorgan
  Comment:
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- * If the average height is 5 metres, then the required opening can be calculated in cm as 500 times that, 50/(wind speed in km/hr).
+ * If the average height is 5 metres, then the required opening can be calculated in cm as 500 times that, 50/(wind speed in km/hr).  Five cm for a 10kph wind.