The Japanese Government actually has a "Cool Biz" campaign to reduce office air conditioning energy usage by relaxing traditional dress code https://en.wikipedia.org/wiki/Cool_Biz_campaign
For me, 21-22C is comfortable, but anything more than that will have me sweating and affect my productivity.
But even if I'm an outlier (I don't think I am?), 28C is surely too hot for most?
I look forward to this trend continuing and spreading.