Top 6 in Top 10 ways to reduce heat for homes in summer.
This is essential as it helps to extort hot air flow due to cooking or after you bathe out your house.
Ideally, make ventilation from the bottom up. After bathing, turn on the ventilation fan for an additional 20-30 minutes so that the hot air escapes. Feel free to turn on the ventilation fan and don't worry about the cost because the ventilation fan consumes very low power.