Why are sash windows best for ventilation?
The short answer is because of physics!
Well, unlike any other style, sash windows (at least the ones which aren’t painted shut) can be opened at the top and the bottom, doing so you’ll harness the power of natural ventilation, free air conditioning, because of physics.
We’re taught at school that warm air rises, and because cold air is heavier than warm air, it drops to the floor, in turn helping push warmer air upwards.
Warmer, often stale air, escapes through the gap at the top of the window, as it does so it allows even cooler air to enter the room at a lower level, which in turn pushes up the warm air, starting a free, natural, zero cost, yet continuous, air conditioning system!
This natural ventilation happens far quicker than any other window style with equivalent opening areas. Unlike casement windows which actually trap stale air, moisture, and spores in the top half of a room, sash windows typically exceed 4 complete room air changes, every hour
So make sure you ask about the Air Changes per Hour your windows will achieve!