Air flow is our friend.
The body responds to moving air, it's how our bodies cool down.
If you don't believe me, blow on the back of your hand. You will see that it feels nice and cool, even though you're blowing air on to your skin that is more than 90 degrees.
That's how the body works, it responds to cool air.
If you have a hot cup of coffee or a hot bowl of soup, you blow on it to cool it down. It's the same with your house. You need to "blow" on your house to cool it down!
When you install a whole house attic fan, what you're getting is air flow, enough air to cool the entire house.
For the fans to run properly, you have open whichever windows serve you best. It could be the kitchen windows in the morning, it could the basement windows when it's hot outside, the family or living room windows in the evening, and of course, the bedroom windows at night.
If air flows in from somewhere, it then has to go out somewhere else.
Just like breathing.
When the fan pulls air in through the windows, it blows it into the attic. In order for more air to get into the house, the air in the attic has to leave. Since there's no window in the attic, you have rely on the ventilation that the builder and roofer have installed. There is some ventilation there already, but not enough for all the air to move out of the attic.
Just like getting onto a bus filled with people, you have to wait for some people to get off the bus before you can get on. The air works the same way.
If not enough air leaves the attic, not enough air can flow through the house. So while the fan works, it doesn't work as well as it could. Which means you will not get as much air flow through the house. Adding more ventilation solves this problem, and the house gets as much air flow as it needs to cool down.
So, let your house do the breathing with a whole a house attic fan.