> Most ordinary working people can't afford the cost of installing a system. Even a portable one.

I just watched a video where a person bought a £200 portable unit. He was using it in the UK and said he spent about £0.89 / day. And I'm assuming they won't use it for that many days a year.

Seems affordable enough for "most ordinary working people"

https://www.youtube.com/watch?v=jOmzVWTH3xo

As a side note, it's nearly impossible to buy a dual-hose portable AC in the UK and Europe. For whatever reason, the market has converged on inefficient single-hose portable ACs.