Question

why are ventilators in houses provided at the top of walls​

Answer 1

Answer:

Ventilators are provided in the rooms at the top of the roofs, just below the roofs because if the air inside the room gets hot the hot  air rises up and flow through these ventilators and thus cool air remains at bottom so that to relive in hot summers

Explanation:

Answer 2

Answer:

A house having windows but no ventilators should not be bought. This is because warm air is lighter than cold air and therefore, it goes up. This warm air can go outside the house mostly through ventilators. If there are no ventilators, then the warm air cannot go outside easily.