The most important words to remember when you think of summer cooling are:
White Reflects Heat!
If you can apply these simple principles you may very well keep your home cool in the summer without expensive air conditioning.
Now we are very fortunate in our short summers in that we live in an old Victorian House with 11 foot ceilings. All our heat rises up above the living spaces. We are very cool. (Note: this is a negative in the winter --all our heat rises above the living spaces --laugh.)
However, many people live in homes with standard 8 foot ceilings which don't give people much room for the hot air to rise above them. You need to exhaust this hot air from your home. One easy solution is a few well place window fans. The need to be in the TOP of the windows sucking the hot air out of the house. This will give the rising hot air somewhere to go.
Another solution is to open the attic door or ceiling vent and let the hot air rise to the attic to be exhausted from there. Just opening your attic door will produce an visible breeze as the hot air rushes upward -- away from the living areas!
Ceiling fans can also draw the heat upward. make sure the blades are canted the right direction to pull the heat UP. You can change the cant in the winter to send the heat down.
Another way to keep the house cool are reflective drapery liners or shades. White reflects heat! So in the summer line your drapes with cheap white sheeting pinned or velcro on. Or buy inexpensive white window shades. Pull them to cover the windows when the sun in on the windows to reflect the heat back out side. You don't want solar heat gain in the summer! (Note: In the winter black or dark liners catch heat to warm your house..)
Long term, you can plant trees that loose their leaves in the winter on the south side of your house to shade it and block the sunlight cooling your home. Or you can add summer awnings to shade south facing windows.
So simply remember:
and you should have a cooler, cheaper summer!