Mitigation of Person-to-Person Infection Transmission

ASHRAE Epidemic Guides coming out will address some of above. In addition, we need people to feel "Safe" at work.  Education helps, facts, data and information can go a long way. But it is asymptomatic people doing much of the spread.  How do people feel "Safe" sitting next to another even 6' away? We can follow the successful footprints in the sand from the cities that went through SARS, Bird Flu, and COVID-19 with relatively small impacts – Hong Kong, Taiwan, etc.  In those cities, wear mask is a standard during pandemics – it is a “source control” to not allow the virus goes out from asymptomatic, as much as a protection device for the healthy.  Also a recommendation from CDC. But, will we listen to CDC? Best,
LL   

Kim, We have also had similar discussions at CMTA.  In addition to UV, another simple measure we have discussed is bi-polar ionization which is typically very cost effective.  This at least has a chance of reducing some of the airborne threat within the space.

Bi-polar ionization can be an option.  Note below from ASHRAE Epidemic website coming up... ----------------------------------------------------------

• High voltage electrodes create reactive ions in air that react with airborne contaminants, including viruses. This process is commonly termed “corona discharge.”
• Systems have been documented to range from relatively ineffective to very effective in reducing airborne particles.
• Systems have been evaluated to either show benefits or no benefits for acute health symptoms.
• A convincing body of scientifically-rigorous, peer-reviewed studies does current exist on this emerging technology; manufacturer data should be carefully considered.
• All systems emit ozone, some at high levels, and are thus subject to special attention.

One thing I know is that the engineering field has a tendency to throw engineering "stuff" at problems and create unintended consequences. We need to proceed with care, and borrowing from the medical field, apply the precautionary principle. 
We're starting by discussing the nature of the facilty and how it should be classified. I have a hard time believing that in a future pandemic, that a school, office, movie theater, etc. is going to be excluded from a lockdown, regardless of what types of systems are designed. So, excluding the buildings that will need to run during a pandemic (hospitals, emergency calls centers, etc.), the conversation is about a greater recognition for designing healthy spaces and doing what we can to reduce the transmission of normal influenza and harmful bacteria. 

The science on most of the technologies out there is pretty weak, and rarely addresses the potential consequences well. Bi-polar ionization for example seems to wipe out pretty much all the microbes in the air stream. We're learning more and more about the importance that they play in our physiological health, so I don't know that we like that approach. The manufacturers of the tech have also misapplied research to try and advocate for letting CO2 levels get up to 2,000 PPM, when the research that they themselves cite says they don't know the impact on cognitive function and are primarily addressing physical ailments like your bones being dissolved in a CO2 rich environment. Not exactly the type of study I want to leverage for creating a good school environment.  

Germicidal ambient LEDs are another one. Again, the science is out on that still - my colleague wrote about that here: https://www.facilitiesnet.com/hvac/article/Germicidal-Ambient-Lighting-Has-Potential-But-Caution-Is-Warranted--18486

The strongest evidence we've seen (multiple studies, peer-reviewed, good sample sizes) is in ventilation, humidity, and UV (though probably best to look at that as a proxy for daylight). Of course, those have potential consequences too if not done right - for example, blanket applying 40-60% humidity at buildings with average envelopes in cold climates creates condensation at cool (not even cold) temps, which leads to mold-->asthma-->immunocomprimised and makes you more at-risk for Covid-19.

So all that said (and presuming that we still care about climate change in how we tackle this), I think we're going to continue talking about:

• Passive house principles, so we have a kick-ass envelope and can consider humidifying a building without creating mold problems.
• Higher ventilation rates w/ERVs
• Displacement ventilation
• Daylight

Not exactly exotic stuff, but for most buildings, I don't think we need exotic solutions. 
​  

Great post Kim.  We are also meeting internally later this week from a healthcare design perspective and can report back any interesting discussions.  Some initial thoughts:

• I agree with Luke that this is a social challenge as much as a physical one. People are going to want to know how their buildings are protecting them. Pro-active communication will be really important.
• As Kim mentions, hospitals are in principle set up pretty well for this type of scenario; at least in the primary care areas. Seems like some of the primary issues are supplies and easily convertable space. Those will certainly be key focus issues going forward in design and retrofit.
• I think this really pushes us away from systems that mix the room air - especially in densely occupied spaces. What better place for the pathogen to go than straight up to the ceiling and out of the room? Pete mentioned displacement; radiant systems can help with this too. 
• Do open offices finally get localized ventilation?
• I can appreciate the studies behind 40-60% RH but this is just really tough. Vapor diffusion is just so hard to manage; room through envelope is certainly as issue.  Room to room inside the building will be really tough too. It will be an endless 'leak' throughout the whole building.  How much do we want that energy intensive system to run?
• I agree with Pete that gadgets often seem to address symptoms and not root causes. It can be tough to apply them effectively as intended, sometimes they break and don't get fixed. Can be an expensive maintenance/energy item. (like the dehumidifier in my 1940s, no vapor retarder behind the concrete basement....)
• Maybe this changes some perception on how much time we should spend indoors - or at least not the same building 8 hours a day, every day.
• I bet we start designing our homes a little differently.  who has done even a small 're-model' at home since the quarantine??

I really love you all and enjoy the conversation here.  Brian's point about alternatives, Adam's rational thinking, Pete's passive ideas and Kim who started this whole thing...there are so much to learn, and so little we know. Something about DOAS, besides energy savings, almost romantic.  The below chart reminds us DOAS ASHRAE ventilation rate is less than 1 ACH, so even with high MERV filter, it may not be as efficient, with time, compares to high ACH system though they may return air.  Any thoughts on this? Best, LL