Originally Posted by
catnhat
In addition, if your house has a southern exposure, close your blinds during the day while your house is under a "Solar Load", it will have a significant reduction on the heat gained inside your house during the day.
And if you can, install a zoned system, 1 heat/ac zone for the first floor, and 1 heat/ac zone for the second if you have that configuration. That way, you will probably only need to turn on the ac at night for the second zone (upstairs). Not as much square footage, cools down fast, sleep well.
When we turn our AC on, we keep it around 75F.