Thread by @joeyfox85

ASHRAE Control of Infectious Aerosols - Equivalent Outdoor Air Rates

The new standard is out and can be found here. osr.ashrae.org/default.aspx

Here's a quick review of the rates that are recommended.

1/5

The recommended equivalent outdoor air rates can be found in Table 5-1 on page 4. They are overall very high. For reference, WHO recommends 10 litres per second (lps)/person and OSPE and Lancet recommend 13.5 lps/person.

2/5

Using standard densities from 62.1 at full occupancy, I've converted these rates into air changes per hour and what CO2 level you would expect to have if outdoor air was the only tool used (it won't be, but this is just for reference).
3/5

>8 ACH for classrooms. Compared to standard indoor air quality in 62.1 for educational facilities, the rate is about 3x higher. I think once and for all, we can agree that ASHRAE minimums for IAQ are woefully inadequate for infection control. We now have a better goal.
4/5

I'll have upcoming threads discussing more aspects of this standard, but I think this is the main thing people have been looking for.

For those who want to know, here are the assumptions in doing the CO2 and ACH calculations.

5/5

Should have been more clear. This isn’t the final standard but the initial public review. Things can change before final release.

https://twitter.com/coolaircoil/status/1657032019774152705

Apologies. There was a typo when copying the values for healthcare equivalent CO2 levels. Here's the updated chart.
If anyone knows typical occupant density in healthcare resident room and common treatment area, I can estimate ACH at full occupancy. I don't know those values.