There are 2 different methods of ventilation, one is passive and one is active. In either case, all attic ventilation systems need good fresh air intake. With proper intake, the attic can breathe. When an attic breathes, it will be cooler and less humid which in turn reduces your electricity costs.
So how does one go about seeing if they have adequate ventilation and which type of ventilation is best. To start, let’s talk about intake. A simple test is to go into the attic (safely) and look where the soffit vents are located. If you see daylight around the perimeter, then you know air can flow in. If you don’t see daylight, or you see very little, then this must be corrected.
There are formulas to determine what kind and how much ventilation you need.
You want to exchange the air in your attic 8 times per hour – therefore passive ventilation does not work as well as active ventilation. This is why attic fans are more effective at cooling an attic than passive ventilation such as ridge vents or turbans (whirly birds).
With active ventilation, an electrical or solar attic fan will create the pressure difference to make the air flow through the attic. In many cases it is much more effective than passive ventilation. And from a long-term cost basis, the solar attic fan will cost much less because they use no electricity! And with the goal of reducing the homes energy costs, this is a big help.
Another advantage of solar attic fans is the 30% federal tax credit available this year on the installed fan. On a standard installation, this can save you $140 or more, thus helping to reduce the cost. Also most solar attic fans are very quiet, unlike electrical fans.
In most cases, I recommend solar attic fans to help cool down the attic. They lower your air conditioners temperature and allow your air conditioner to cool your home more efficiently, saving money and wear and tear on your A/C system. Another benefit is that your roof will last longer when your attic is properly ventilated.