Thread by @WolfgangFeist

@fionnstevenson @ElrondBurrell @Conversation Actually, this article talks a lot - but gives no practical recommendation.

#Passivhaus has always recommended 30 m³/Person/h fresh air supply. The air exchange rates given by this will be different in a school/a kindergarden/an office (with e.g. only 1 person sitting there).

@fionnstevenson @ElrondBurrell @Conversation Do the math! In a typical school room that will be 3...6 ach. But, keep in mind, what you can implicitly read in that article: Even the highest vent.-rate will not 100% protect you; yo'll have to wear a mask, too. Because the droplets are in the airstream; and still can hit you

@fionnstevenson @ElrondBurrell @Conversation These are all academic discussions. Now let's be clear, what could be a best possible path to protect us:

1) If indoors and together with other people - wear a mask, and a good one. The mask can't be substituted by ventilation.

@fionnstevenson @ElrondBurrell @Conversation 2) Ventilate the room as good as possible - but don't "overventilate" in winter, because *dry air* will make you sick. ERV and HRV will make this easier to achieve, but humidification might be needed.

@fionnstevenson @ElrondBurrell @Conversation 3) Keep indoor humidity between 50-60% during such a virus pandemic. Lower rel. hum. lets the virus stay longer in the air and also makes humans more susceptible for infection.

(How? If not installed in the system, use an evaporative humidifier. These are not expensive.)

@fionnstevenson @ElrondBurrell @Conversation 4) Clean the surfaces people are in contact with in regular intervals. That's another infection path. The virus from the big droplets can sit on a surface for quite a time.

@fionnstevenson @ElrondBurrell @Conversation 5) Using air cleaners might help additionally. If equipped with an adequate filter (better than MERV16, F9), these will reduce aerosols significantly. This is especially a method, if you have a potentially infected person at home.

@fionnstevenson @ElrondBurrell @Conversation 6) If we are @ this home setting: infected persons should stay in a different room.Have the window open in that room (even in a passive house, you see, why we have always recoomended openable windows ) & close the door to that room. Wear a ffp3 maks (thats for 14 days at maximum)

@fionnstevenson @ElrondBurrell @Conversation Just to give us a relation: In Korea, they checked for infection rates in the households of infected persons and found these to be less than 30%. So, yes, you can protect yourself.

@fionnstevenson @ElrondBurrell @Conversation And now, lets be honest:The danger comes from these 1 to 2 days a person might be infectious but presymptomatic. The problem is:You just don't know. It's crazy,but if we are dealing with high incendence, there is no other way than to assume,that any person you meet,IS infectious

@fionnstevenson @ElrondBurrell @Conversation That was the reason why all responsibly thinking persons try to keep the infection rate low. THAT is easy (yes, it's easy!): Keep the distance, wear a mask, avoid large indoor gatherings, wash your hands.

@fionnstevenson @ElrondBurrell @Conversation This alone will not reduce your personal risk to zero - but it will reduce the R-factor to smaller than 1. And that would lead to reduced infection numbers day after day after day ... until these become so small, that the risk becomes low.

@fionnstevenson @ElrondBurrell @Conversation Exampel:R is in the range of 1.2 to 1.3 in Germany right now. If we improve proper mask wearing,number of huge indoor gatherings,ventilation,... by just 40%, R will come down to 0.9 & we'll have a falling exponential. Still, it reduces your personal risk at the start only by 40%.

@fionnstevenson @ElrondBurrell @Conversation If you want to reduce your personal risk in an "infectious environment" with high incidence, you'd have to improve by (90%? 95%?); what would mean wearing ffp3 all the time, ventilate like hell (is 10 ach enough???), clean all incoming stuff and you still might get it from..,

@fionnstevenson @ElrondBurrell @Conversation ...from a piece of deep frozen meat coming form an infected meat factory (e.g., there are potential other paths, too. We just don't know them all).

@fionnstevenson @ElrondBurrell @Conversation Conclusion: If (most of us) act responsibly,we could drive R down below 1 & start a declining exponential; the small incidence remaining (you see that in Korea, NZ, ...) can be kept under control by test/trace/quarantine.Until the vaccine arrives, what will be Jan2021 the latest

@fionnstevenson @ElrondBurrell @Conversation @threadreaderapp please unroll