I just moved to Portugal and had zero issues installing a portable unit to help me survive the heatwave. For the hinged windows you just grab an installation kit that works with them and you're good to go. The only problem is that the portable AC I got is not a window unit (& it's single-hose), but I wanted to have it before the heatwave started and don't care too much about few percentage points in lost efficiency as long as it keeps me and my pets alive. Total cost was €320 with the installation kit for a 12000BTU unit.