Doesn't matter what it looks like, problem is it changes the facade. For that you need to submit some paperwork and get it approved. You can actually install a

Doesn't matter what it looks like, problem is it changes the facade. For that you need to submit some paperwork and get it approved. You can actually install a heat pump in most apartment buildings, as long as it's on the balcony and not visible from the street (=below waist-level). Main reason you wouldn't, is condensate output which has to be piped indoors or into a heated drain during the winter. Or you just pipe it into your balcony's rainwater drain and accept that you can't use the heatpump below 0C.