These findings are shared for research purposes and indications for decision makers to help them broaden perspectives and expand understanding until they materialize in a reviewed paper.

HVAC (Hot Cold Air conditioning)

Most modern AC units are in fact HVAC.



J Lu, J Gu describe how transmission was proliferated by an A/C unit in a Guangzou restaurant through droplets or aerosols


As per L Dietz P F Horve explain « . However, for most buildings, the easiest way to deliver outside air directly across the building envelope is to open a window. Window ventilation not only bypasses ductwork but increases outside air fraction and increases total air change rate as well (79). Administrators and building operators should discuss a plan for increasing perimeter, and specifically window, ventilation when outdoor temperatures are adequate for this practice. »


Beyond that restaurant, the immense majority of clusters were closed spaces, poorly ventilated or ventilated, cooled, heated through an AC mechanism


Health Care facilities or Hospitals → Always HVAC

Slaughter houses → Always HVAC

Schools → Sometimes HVAC

Hotels → Mostly HVAC

Social facilities → Often HVAC

Discotheques → Often HVAC

Subway/Metro → Rarely HVAC but artificial ventilation

Buses → Often HVAC

Companies → Mostly HVAC

Worship places → Rarely HVAC 

Family reunions → Sometimes HVAC

Gyms-→ Mostly HVAC

Call Centers-→ Mostly HVAC




Our analysis of available AC Demand shows a strong correlations between Commercial demand as per JRAIA 2018 data and death until June 25th as per worldometer at significance level of .1 using 15 European countries whom are towards the end of their epidemic wave and for whom data was available.










Absolute death count as of June 25 from Worldometers are associated with:

Commercial AC demand 2018 – strong correlation at 0.86

Total AC demand 2018 – moderate to strong correlation at 0.71

Commercial AC per capita – moderate correlation 0.58

Death per capita is associated with:

Commercial AC demand 2018 – moderate to strong correlation at 0.77

Commercial AC per capita – moderate correlation 0.64

Total AC demand 2018 – moderate correlation at 0.61


Significant at .1 level based on 15 European countries whom are at the end of their epidemic wave.







« Our results suggest that improvements of ventilation in high density public spaces could be an important and relatively easy-to-implement strategy supplementing vaccination » ...« correspond to a vaccination coverage of 60–70% for an efficacy of 40%, 50–60% for 60% efficacy, and 40–50% for 80% efficacy. In the aerosol model, consistently improved ventilation beats vaccination even with full coverage if efficacies are low. » can be done fast  and it works for aerosol, droplets known and yet unknown viruses


All five hardest hit cities had a high concentration of modern office buildings and hotels with shared and/or a culture for centralized AC for heating or cooling in office buildings, malls, homes (London, New York, Madrid, Brussels, Milan)

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