The National Construction Code was updated in 2013 to introduce measures to safeguard children from falling through openable windows. The main change was to bedroom windows with bedroom windows on the second storey and above requiring devices to restrict the amount the window can open, or screens. (This is a very simplified version of the requirements, more detail is available here www.breezway.com.au/building-code-compliance/fall-prevention-through-windows/)
The amount of ventilation through an Altair Louvre Window with its openings restricted is relatively unaffected, but for many window types a restricted opening device will severely reduce the ventilation through the window.
Above is a picture of a home we spotted recently in subtropical Brisbane where it appears that the chain winder of the window has been detached and a piece of timber is being used to hold the window open, most likely in an attempt to get some fresh air into the room. Looking at the other windows, which are presumably fully open, it is easy to guess that the homeowner will be looking to install a different window type, or screens, sometime in the near future.