This house in Chifley had a cathedral ceiling (sloping ceiling parallel to the external roof with no roof space) which has very limited insulating capacity against summer heat penetration. I devised a controllable ridge vent which could enable a buoyancy ventilation system (see Mawson ridge and ventilation system pages) to purge the gained heat at times when the external temperature was lower than inside.
Also a way of increasing the insulation value of the ceiling which was independent of the vents.
I don’t know if they actually constructed it.