European windows open on hinges, they don't slide. This makes it hard to install such an unit and keeping the window airtight. It's also hard to get agreement

European windows open on hinges, they don't slide. This makes it hard to install such an unit and keeping the window airtight. It's also hard to get agreement from landlords (most people rent), so many people get portable units that blow hot exhaust air out via a dryer-vent style hose. That get stuck out the window, and the window is poorly air-tightened using a velroed-on barrier. The advantage is that it requires zero "modifications" and thus you can just do it. The downside is that they're horribly inefficient.