Local conditions
The sun that ruins a room on this coast arrives at seven in the morning and four in the afternoon
Low Sun Walks In Under The Roofline
Byron Bay to Brisbane, the coast runs north to south, and the glass everybody paid extra for faces east over the water. That sun arrives at first light, almost level, and it comes in under the eave rather than over it. The Your Home guidance on orientation is blunt about why: east and west glass is the hard case, because the sun sits low and an overhang cannot reach it. That is the argument for doing the work at the glass itself, on those two aspects and rarely on the others.
The same thing happens in reverse at the end of the day, on the western wall, over the hinterland — except by four o’clock that glass has had the whole afternoon to warm up. An absorbing fabric hung there has spent three hours soaking up the load and is now a warm panel sitting inside your window. A metallised backing turns most of that around before it becomes heat you have to live with, and that is the only reason to pay more for one.
A 600mm eave shades a west-facing window beautifully from about eleven until two, which is not when anyone is sitting in the room. Same fabric, same house, and the answer still changes with the aspect — which is why we ask which way the window faces before we quote anything, in Brisbane and on the Gold Coast alike.