BUYING A HEPA FILTER FOR YOUR HOME 🧵
I've been asked about sizing a HEPA filter for your home. This is different than sizing one for public spaces with other people.
This does not provide fresh air. Ventilation is required for that. Here are some things to consider:
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I've been asked about sizing a HEPA filter for your home. This is different than sizing one for public spaces with other people.
This does not provide fresh air. Ventilation is required for that. Here are some things to consider:
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WHAT IS YOUR GOAL?
Do you just want to improve the air quality in your house in general or do you want to have a gathering and use the HEPA filter to mitigate risk of COVID transmission? The clean air delivery rate (CADR) for these two goals is very different.
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Do you just want to improve the air quality in your house in general or do you want to have a gathering and use the HEPA filter to mitigate risk of COVID transmission? The clean air delivery rate (CADR) for these two goals is very different.
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For basic air quality improvement, go here: ashrae.org/technical-reso…
Click on standard 62.2-2019. Top of page 8 has a table based on house size.
Consider poor air mixing between rooms. Ex - your bedroom door is closed. HEPA filter outside won't help.
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Click on standard 62.2-2019. Top of page 8 has a table based on house size.
Consider poor air mixing between rooms. Ex - your bedroom door is closed. HEPA filter outside won't help.
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MITIGATING COVID SPREAD
Note: this reduces risk, but not a guarantee against transmission.
Imagine COVID leaving someone's mouth like invisible second hand smoke.
The HEPA filter does the opposite, it sucks in that smoke and puts out clean air.
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Note: this reduces risk, but not a guarantee against transmission.
Imagine COVID leaving someone's mouth like invisible second hand smoke.
The HEPA filter does the opposite, it sucks in that smoke and puts out clean air.
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If a HEPA filter is in one room and you and someone else are in a different room, it won't do much good. You need to be breathing in the filtered air.
How much is necessary? I can't say with certainty, but old ASHRAE guidelines for smoking lounges are 60 CFM/person.
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How much is necessary? I can't say with certainty, but old ASHRAE guidelines for smoking lounges are 60 CFM/person.
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Old guidelines for smoking areas in casinos and restaurants were 30 CFM/person with a note "supplementary smoke-removal equipment may be required".
If you are relying on ventilation and filtration to mitigate spread, distancing is very important.
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ashrae.org/File%20Library…
If you are relying on ventilation and filtration to mitigate spread, distancing is very important.
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ashrae.org/File%20Library…
COVID isn't smoke. I don't know the necessary CADR, but this provides a basis for comparison.
BEDROOMS
Another thing to consider - if you want clean air while you sleep, then it's much better to have a HEPA filter in your bedroom. A smaller one will be sufficient.
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BEDROOMS
Another thing to consider - if you want clean air while you sleep, then it's much better to have a HEPA filter in your bedroom. A smaller one will be sufficient.
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OTHER CONSIDERATIONS
I've discussed guidelines on finding the CADR. These are a minimum. Nothing wrong with more. The other considerations are cost and noise (avoid ionization). For your bedroom, you'd want it very quiet. Here's a comparison:
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I've discussed guidelines on finding the CADR. These are a minimum. Nothing wrong with more. The other considerations are cost and noise (avoid ionization). For your bedroom, you'd want it very quiet. Here's a comparison:
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https://twitter.com/marwa_zaatari/status/1429629474878988288?s=20
There is a middle of the road option between minimum residential ventilation and COVID mitigation. You can use the sizing advertised with the HEPA filter. That should give > 4ACH - good air quality.
Or you can calculate it yourself:
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Or you can calculate it yourself:
https://twitter.com/joeyfox85/status/1475854507326291968?s=20
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What do I do?
#corsirosenthalbox ! A large one for the main floor and mini CR boxes for the bedrooms. Run them all on low.
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#corsirosenthalbox ! A large one for the main floor and mini CR boxes for the bedrooms. Run them all on low.
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