I've seen the window units in NYC. They wouldn't suit Ireland at least. Window construction is much more solid and geared to keeping heat in. I have a HVAC unit in the pharmacy and it is worth every penny. The main unit is fixed to the outside wall at the back and then plumbed into a ceiling unit in the middle of the pharmacy. Strictly speaking I should have got planning permission to have it fixed to an outside wall but nobody who cares can access the yard where it resides so it just sits there.
generally speaking here it is seldom hot enough to warrant air con in residential buildings. Places like hospitals and commercial premises would have full scale units installed. That is to say the newer ones. There was a moan/rant on the radio today about a major hospital in Limerick (south west Ireland) with no air con on most of the wards. Once the sun reached a particular point in the sky the patients started melting. OK exaggeration. But the bed bound ones where stuck in direct sunlight with windows that only opened a few inches for up to 8 hours.
Also air con units needs a stronger than regular power supply (at least here any way.) The ones that you just plug into the wall would barely pass muster.
My portable unit can cool a single room very effectively. If I use it carefully, with judicious use of doors, windows and curtains, I can keep the whole house a few degrees cooler than outside. It's a small house!
Welcome to Britain, if you don't like the weather, just wait a minute, some more will be along soon.