Pretty sure in Qld, at least, your right to install aircon has been established in court. As an aside, I also live in a building well designed to have great cross flow ventilation, but that just means when it’s stinking hot all you get is hot air passing through, assuming it’s breezy enough to do so. Ceiling fans also just flow the same hot air. When you can have a moderate priced aircon with a near silent compressor it is hard to argue against it.