So the government has introduced some draft regulations on mandatory heating and cooling systems for rentals in addition to a few other things.
https://engage.vic.gov.au/new-minimum-standards-for-rental-properties-and-rooming-houses
This raises some questions. So for example in some older apartment buildings the outdoor unit of the split system is usually mounted onto one side of the building. In some buildings there may not be enough space to mount so many units, and there's also the question of structural integrity as well.
The regulations also say this must all be done by 30 October 2027. As it stands in this country we already have a massive shortage in trades and a backlog in getting work done. So you've got three years to get all of Vic sorted, which currently I think would be very difficult, and most probably have an inflationary effect as tradies jack up the prices.
As an owner (not a landlord) I remember having to wait a few months to get my a/c installed. Can't imagine what it would be like in a rush to beat a deadline.
Of course people can sell, whether that would dampen property prices or crash them, it's hard to say. But a depressed housing market may have broader consequences in terms of general consumer psychology and create recessionary pressures. It may also lead the landlords increasing rents.
In principal it's a good idea, but I am concerned in practice there's going to be lots of unintended side effects.