Again i m assuming that you re not considering a sealed attic lowering the temperature of an attic that contains ducts can reduce your air conditioning costs.
Best way to lower attic temperature.
A solar powered attic fan would be best.
Adding a radiant barrier to the underside of your attic structure will help reduce heat gain in the space but be sure to check your roof shingle warranty and make sure it would not be voided by such a measure.
They are readily available and easy to install yourself.
It will help to keep the attic much cooler in the summertime.
Install electric ventilators and attic fans which remove hot air from an attic.
The thermostat will usually start at 95 degrees fahrenheit which is the temperature that the attic fan usually starts at.
Alternatively install passive vents such as gable soffit and ridge vents which are openings in the roof that allow hot air to escape.
They have thermostats that turn the fan on at a recommended preset temperature of 100 110 degrees.
Here are ten different ways to reduce your attic heat temperature and save you money.
When reroofing use white or pale gray shingles instead of dark ones.
In existing homes the question is important.
Ideal attic temperatures shouldn t be more than 10 to 20 degrees hotter than outside temperatures.
Gable vents around 25 each plus 75 per vent for labor can lower attic temperatures about 10 degrees.
Also make sure your attic is ventilated.
Get one that runs on a temperature sensor.
Use a thermostatically controlled roof mounted ventilator.