You can fully open windows, outside door and verandas, but you may experience a reduction in the cooling effect if too much hot air is let in. For best results, partially open windows or outside doors that are the furthest away from the air conditioning vents or ducts. In the rooms with air conditioning vents, try to have an exhaust area of open window (or door) that is about twice the size of the vent opening. If there are very hot winds, you can reduce openings on the windward side of the house (where the wind is coming from) and increase the openings on the lee (opposite) side of the house.