HVAC - Ventilation

[RWebb]

https://www.cnn.com/2020/11/19/us/gym-ventilation-covid-trnd/index.html

[cabmandone]

Not gonna open the link. Just gonna say that many new commercial buildings have an air exchange system. Air exchange was a growing market back when I still did HVAC.

[jyl]

Really interesting link actually. They didn’t do it with fancy HVAC, just with ventilation to outside and distancing and (cool) a C02 monitor. I guess it helps that people in gyms are not as prone to getting cold as people sitting in a restaurant.

Germany apparently is really into ventilation as a Covid measure. They have a cultural obsession with fresh air, I believe. Some parts of the US are too hot or humid to open windows wide. In Portland, all summer the weather was nice (except during the fires!) but I still didn’t see most businesses make much effort to open windows. I see more HEPA air cleaners than open windows.

I’ve thought that an HVAC system with air intakes above each table, using pretty authoritative airflow, could be good. But no restaurant has the money to do that.

I’ve also wondered about HVAC systems spreading airborne virus through a building. Don’t think that’s been documented. I did put HEPA filters over the vents in my office. When I have visitors - very rare, maybe once a month, I open the big window by the conference table and run two HEPA air cleaners, and we sit at opposite ends of the table. I’m also quite selective who I’ll meet with and why. Everyone else gets Zoom. And frankly there is very little clamour to meet in person nowadays.

[cabmandone]

Originally Posted by jyl

Really interesting link actually. They didn’t do it with fancy HVAC, just with ventilation to outside and distancing and (cool) a C02 monitor. I guess it helps that people in gyms are not as prone to getting cold as people sitting in a restaurant.

Germany apparently is really into ventilation as a Covid measure. They have a cultural obsession with fresh air, I believe. Some parts of the US are too hot or humid to open windows wide. In Portland, all summer the weather was nice (except during the fires!) but I still didn’t see most businesses make much effort to open windows. I see more HEPA air cleaners than open windows.

I’ve thought that an HVAC system with air intakes above each table, using pretty authoritative airflow, could be good. But no restaurant has the money to do that.

I’ve also wondered about HVAC systems spreading airborne virus through a building. Don’t think that’s been documented. I did put HEPA filters over the vents in my office. When I have visitors - very rare, maybe once a month, I open the big window by the conference table and run two HEPA air cleaners, and we sit at opposite ends of the table. I’m also quite selective who I’ll meet with and why. Everyone else gets Zoom. And frankly there is very little clamour to meet in person nowadays.

I read the article when I opened MSN this morning. They went old school with air exchange. That method gets REALLY expensive as the temps drop but they have a mask requirement if the doors are closed and are using 10' spacing. I did find the Co2 monitor interesting.

[billybek]

Our building at work has 100% fresh air when in the occupied mode.
There is a massive heat wheel system to recover heat from the exhausted air.
The new(er) buildings at work were all built to this standard but the older buildings are still in the stone age when it comes to heat recovery and ventilation standards.

[Rtrorkt]

remember that most office HVAC systems utilize a plenum return meaning all of the return air is pulled above the ceiling finding its way to the central return duct. Along the way it picks up what ever is along the path. Most filters are MERV 8 sort of like your house. Just sayin

[Oracle]

That article has very little resemblance to a regular office space.. and its deceiving. Besides if you live in a cold climate are you just going to leave the door open?

I own/run a company that we clean HVAC systems in offices and you would not believe what we find in the air ducts... By now all of my guys swear to never work in an office! (especially on older buildings).

Anyway, a poorly maintained HVAC system can absolutely carry airborne particles that can include COVID-19 virus. Here's an article from the CDC if you have any doubts:
https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article

My advise to all of you who work in a building: Ask the landlord to show you hard evidence the HVAC system (not just the motors or grills) have been cleaned by a company with a NADCA accreditation. If they can't or they won't then work from home, seriously.

[Zeke]

Originally Posted by Oracle

That article has very little resemblance to a regular office space.. and its deceiving. Besides if you live in a cold climate are you just going to leave the door open?

I own/run a company that we clean HVAC systems in offices and you would not believe what we find in the air ducts... By now all of my guys swear to never work in an office! (especially on older buildings).

Anyway, a poorly maintained HVAC system can absolutely carry airborne particles that can include COVID-19 virus. Here's an article from the CDC if you have any doubts:
https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article

My advise to all of you who work in a building: Ask the landlord to show you hard evidence the HVAC system (not just the motors or grills) have been cleaned by a company with a NADCA accreditation. If they can't or they won't then work from home, seriously.

I've been aware of this for years. It isn't a real problem until it is. As Oracle says, building maintenance is too often deferred. And the first cleaning starts when the contractors leave.

[RWebb]

a few fluid flow tidbits in lay language:

https://scitechdaily.com/aerodynamics-of-infectious-disease-airflow-studies-reveal-strategies-to-reduce-indoor-transmission-of-covid-19/

[David]

The offices, break rooms and lockers rooms at our shop have 100% outside air supply to the AC units. The 80,000 sqft of shop space is about 90% recycled air conditioned air but with a 75' high center bay, there's lots of air circulation. Nobody here has gotten Covid-19 yet. Knock on wood!

[mepstein]

"I’ve also wondered about HVAC systems spreading airborne virus through a building. Don’t think that’s been documented."


Legionnaires' disease

[red-beard]