100% agree. In summary, in my stupidity and ignorance I got one of those units for the office with my boss' money, whereas I could have had a passively cooled working place. If all of those units were labeled F for Friggin-retarded-noise-and-cooling-levels, it would have made me look into alternatives, because I did totally look at the energy label and noise level and the vast majority was very similar. I figured this was as good as it gets.

Non-summary version:

In the office, the sun bakes the roof to make our rooms a good bit hotter than outside, open windows or no. I was there for my interview on one of the hotter days that year and decided right then and there that either the company was going to buy an AC or I was. It ended up being the company, but I was fairly insistent about needing one so the money was kind of spent for me. If it had been my money, I'd have considered it a sunk cost and good lesson.

It took about one day of using the device for me to start to wonder about its working principles. I mean, I roughly knew: I own a fridge after all. One side gets hot and you cool it with air that is then blown outside; the other side is cold and you use it to cool air that is then blown into the room. But I hadn't really thought about it until after we owned one:

How can this thing have only one hose? What is the air that it blows out replaced by?

I asked that question out loud in the office and, yeah, given that it only blows hot air out, it must be creating negative pressure in the room and basically sucking that hot outside air back into the room. It's nonsensical. I even sketched out for a friend how it should work instead because they didn't get my issue. Turns out I reinvented the dual host system (which I never heard of until today).

To make matters worse, the ground floor apartment I moved into at the same time as starting to work there is amazing: it remains 22-24°C during the summer, also after 2 weeks of 35+°C outside (thick walls and shaded from the sun; no air conditioning involved at all). I didn't know that was possible.

If I had known that it would be fine to work from home for a few weeks per year and that my apartment would be super cool (literally and figuratively), I would never have insisted on some kind of air conditioning to try and counteract 20kW of sunlight[1] hitting the office windows and roof. I could have saved a ton of power/CO2 and quite a bit of money. To make matters worse, we didn't use to be under the roof, we used to have only morning sun through the windows. It was only slightly cooler than the new place, but this unit could actually manage to cool the room down.

But now we've chosen this course and I feel too guilty to say that we should just consider it a sunk cost, I'm not going to use it, it's so loud I can hardly concentrate, and I'll just work elsewhere during the hottest weeks. Can't do it. Recently, one of our smaller windows was replaced with some insulated plates with a hole cut out exactly for the AC hose in an attempt to make it work better. I think it does work better because it's less leaky than the flexible thing we had before to put in the window crack, but it's still a huge waste and we keep sinking money into this shitty "solution".

I don't even get it. Like, how hard is it to put a horizontal piece of foam in the hose and have the dual hose system in one hose? Make sure the hot side is on top and put fins at the end of the top half to make the hot air be blown upwards. May not be as efficient as having them be in separate hoses, but wouldn't that be a lot better? It's also not as if you'd be putting cold air next to hot air: it's about the already-hot outside air that would be running alongside the slightly hotter waste-heat air.

[1] https://hypertextbook.com/facts/1998/ManicaPiputbundit.shtml 1.4kW/m² multiplied by an estimate of window and roof surface area of the single room that the AC is in.