How many windows open with whole house fan?

When using a whole house fan, it's generally recommended to open at least one window in each room to allow for proper airflow and ventilation. The exact number of Windows will depend on the size of your home and the fan's capacity, but typically, opening 2-4 Windows strategically throughout the house can help maximize the cooling effect. Ensure that Windows are opened on the opposite side of the house from where the fan is located to create a cross breeze.