The end is near for a reno, with an unusual delay - COVID-19. Nearly all is sorted, but I have a query. The toilet window size meets the BCA code. This window is louvres, so there is no way to stop outside air entering. The intent was to have a hinged window (no room for anything else) so that the window can be left open, closed or between. One tradie said that a fixed window with a strip of flyscreen about 100 mm deep at the top will do the job. I'm not keen as air from outside can still enter, albeit near the ceiling and through a narrow gap. Can someone please advise if this meets the BCA and if it is desirable? TIA.