Just curious, why do these threads keep appearing? There was one for Japan too. These are generally pretty modern areas with good building HVAC in my experience. What is an "issue with air conditioning"? And how could it, statistically, be the case that the conditions outside are always better than what the HVAC system is capable of maintaining in terms of temperature, pressure, air exchange/turnover, humidity, IAQ (particulates, etc.)? Is there a high presence of buildings with hydronic systems that create issues during the shoulder seasons, is that it? I wouldn't think it to be the case in Japan, but I suppose that could be common in some older properties in Europe.

As someone who works in the building engineering field, albeit in the US, I am genuinely curious here, so I don't intend this as an affront in any way.

Are these threads really about some double meaning, like people trying to covertly smoke?