3 ms·

I have a few thoughts. One: that even if the C02 seems fine, if the din of the room means everyone is shouting then viral dispersal will be much higher. Two:

by djmips 4y ago

I have a few thoughts. One: that even if the C02 seems fine, if the din of the room means everyone is shouting then viral dispersal will be much higher. Two: it seems like having fresher air, will be more costly in the winter unless people can put up with lower temperature. I wonder how effective an airplane filter really is with regard to viruses. Should buildings and enclosed spaces be redesigned to include better filtering and at what running cost will that be?

kortilla 4y ago
> wonder how effective an airplane filter really is with regard to viruses. Airplanes are far better than any normal indoor building space. It’s a constant blend of outside air that means the entire cabin’s volume of air is gone within something like 5 mins.
- sampo 4y ago
  > Airplanes are far better than any normal indoor building space. But only when they fly. When you are waiting that 30 minutes sitting in the plane after boarding, the fraction of re-breathed air can get high. People have measured 2000 and 4000 ppm CO2 readings.
  - MichaelZuo 4y ago
    Looking from the chart it seems like the CO2 levels were elevated for the entire flight? As in it never dips below 1200pm on either the short haul or long haul flight. Also with the caveat in the article: "Note that the graphs below aren't calculated for altitude adjustment. Since planes are generally pressurized to an equivalent of 8000 feet, and senor drift is typically 3 per 1000 feet of elevation, it means that while in the air the CO2 levels are likely $24% higher than shown on the graph." It seems the logged numbers are underestimating it.
hedgehog 4y ago
On the energy item modern HVAC systems use a device called an ERV to greatly reduce energy loss to ventilation. No need to turn down the heat to get fresh air. The thermal plume associated with each occupant makes the problem a bit easier too, in general stale air heads to the top of the room because it's warmer and more humid therefore less dense. Not a new idea and some good models to look at. https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://techxplore.com/news/2020-12-ventilation-easy-highly-effective-low-cost.html https://techxplore.com/news/2020-12-ventilation-easy-highly-... https://hackaday.com/2022/07/07/the-benefits-of-displacement-ventilation/ https://hackaday.com/2022/07/07/the-benefits-of-displacement...

by djmips 4y ago

kortilla 4y ago

> wonder how effective an airplane filter really is with regard to viruses. Airplanes are far better than any normal indoor building space. It’s a constant blend of outside air that means the entire cabin’s volume of air is gone within something like 5 mins.

sampo 4y ago
> Airplanes are far better than any normal indoor building space. But only when they fly. When you are waiting that 30 minutes sitting in the plane after boarding, the fraction of re-breathed air can get high. People have measured 2000 and 4000 ppm CO2 readings.
- MichaelZuo 4y ago
  Looking from the chart it seems like the CO2 levels were elevated for the entire flight? As in it never dips below 1200pm on either the short haul or long haul flight. Also with the caveat in the article: "Note that the graphs below aren't calculated for altitude adjustment. Since planes are generally pressurized to an equivalent of 8000 feet, and senor drift is typically 3 per 1000 feet of elevation, it means that while in the air the CO2 levels are likely $24% higher than shown on the graph." It seems the logged numbers are underestimating it.

hedgehog 4y ago

On the energy item modern HVAC systems use a device called an ERV to greatly reduce energy loss to ventilation. No need to turn down the heat to get fresh air. The thermal plume associated with each occupant makes the problem a bit easier too, in general stale air heads to the top of the room because it's warmer and more humid therefore less dense. Not a new idea and some good models to look at. https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://techxplore.com/news/2020-12-ventilation-easy-highly-effective-low-cost.html https://techxplore.com/news/2020-12-ventilation-easy-highly-... https://hackaday.com/2022/07/07/the-benefits-of-displacement-ventilation/ https://hackaday.com/2022/07/07/the-benefits-of-displacement...