1. Consider installing an automatic thermostat that turns off your air conditioner at night.
2. Open windows in the summer. It costs nothing, but it saves energy and money. 
3. Ceiling fans use less electricity than air conditioners or furnaces. 
4. set your thermostat to 25 degrees Celsius or 77 degrees Fahrenheit to provide the most comfort at the least cost.
5. Use awnings and overhangs to keep the sun out of south-facing windows in the summers.
6. We just upgraded the windows in our home.
7. A reflective roof can reduce the roof surface temperature by up to 60 degrees Fahrenheit, depending on your climate.

via ismckenzie