Keep your attic and roof cooler so that the ceiling below is cooler. Since the sun is more intense on the roof it creates more free solar electricity to run the fan, and some models have an adjustable hinged panel to maximize the angle and performance.
They are easy to install in less than an hour and only require about a 12" hole between the roof rafters, and also help to extend the life of your roof shingles by keeping the whole system cooler.
The ROI Calculation factors in energy savings on heating and cooling. The long term savings on the life of the roof are an additional advantage.
Good to Know: The roof may generate a lot of heat in the daytime, but it is also a way in which heat escapes your home. Consider 'passive' ventilation tactics to retain more heat in the winter, and to keep your attic cooler.
'Passive' Ridge and Soffit Ventilation - Use the laws of nature to reduce your energy bills rather than using electricity for a fan. With full length and well functioning ridge and soffit vents, Bernoulli's principle helps you increase the air flow out of your attic. Air and fluid speed increases when moving from a region of higher pressure to a region of lower pressure, so you can literally 'flush' your attic for free at a rate of 1,500 cubic feet per minute with 30 feet of ridge venting, even on a day without much outside wind at all. This approach is far more effective than gable end fans or vents. Many homes have some form of this 'passive' Ridge/Soffit system already built in, but the cost to fix or optimize it is entirely subject to the condition of the home.
Solar Attic Fan - Why not let the sun help cool your attic and extend the life of your roof? Attic fans conveniently fit between rafters and save you money every year
PLUS: Reflective Insulation (Radiant Barrier)
Inspired by NASA technology, Reflective Insulation (Radiant Barrier) is an advanced method of economically making your home more energy-efficient. Unlike conventional attic insulation, which absorbs heat, Reflective Insulation reflects the sun's rays (heat) in Summer and acts as a thermal barrier by blocking heat from escaping in the winter, keeping your living space more comfortable and lowering your monthly utility bills! You can put Reflective Insulation on the floor of your attic, or you can put the foil material on the underside of the rafters. As hot air rises through attics, you can use the space between the rafters and the underside of the roof to guide the air up and out of your house in the summer. This rafter tactic involves stapling roll out foil material across the rafters to trap the air in a 'chase' and guide it up to the ridge vent which is required for this installation. The foil membrane also reflects the heat away from the interior of the attic and typically has a small insulation R Value to further help reduce the heat gain or the loss in winter. Make sure to leave a few inches of air space at the floor level and at the ridge to increase the ventilation factor and take advantage of the Bernoulli principle. Work with a professional to determine if your attic is best suited for installation at the floor level or along the rafters, and not all reflective insulation is created equal! Make sure to check on the consistency of the perforations to allow moisture through and prevent condensation that can lead to mold and harm your house. See the Video: 'The Future of Energy Savings Video' Comfort Guard Contact an expert Reflective Insulation Installer: Comfort Guard Installers
Great prices and selection at house needs Click Here
Also see adjustable panel fans to increase performance Click Here