Local conditions
Most of the heat here arrives through the glass
Single Glazing And A Western Wall
A great deal of the housing stock between Brisbane and the Gold Coast is single glazed, and glass is where the heat gets in. Glazing is one of the biggest thermal weak points in an Australian home, and on a western elevation in February a large single pane behaves like a radiator from about three in the afternoon.
A honeycomb blind is the only internal product that does much about that, because it holds still air against the glass rather than simply absorbing the light and re-radiating the heat into the room. It is not double glazing and we would not pretend otherwise, but on the wrong window it is the cheapest useful improvement available.
Where it is wasted is the small shaded window, the room that is air conditioned anyway, or any opening where the real problem is glare rather than heat. Those are roller blind windows, and it is not in our interest to say so, which is rather the point.