ok, Im going to assume you do not live in death valley, and you do not have a glass house.
can you give us your location, your home design (number of windows and how large, and which direction they face) and the Gross square footage on each floor and how much overlap between them. also, describe the upstairs, the access, and the ceilings.
describe your roof, and attic ventilation as well. also, the shading around your house, and the overhang/soffit design.