Solar Fan Benefits
Lowers attic temperature which reduces the load on the HVAC System and saves money.
The most obvious reason for attic ventilation is to lower attic space temperature during the warmer months. Attic temperatures can exceed 160F during hot summer days. Proper attic ventilation can reduce those temperatures by up to 50F. No matter how much insulation is in the attic, heat can still transfer into adjacent living spaces. In fact, extra insulation can actually add to temperature increases because heat is trapped in the insulation. Proper ventilation evacuates this excess heat build-up. As the heat is exhausted, the work load of the air conditioning system is reduced, thereby saving energy and extending the life of the air conditioning system.
Extend the life of the roofing materials.
Though asphalt shingles are designed to take the abuse of the sun for many years, they are subjected to greater temperatures when the roof decking is allowed to overheat, which is just what happens in an under ventilated attic. In the cooler months, moisture is the most serious concern. Even with the use of vapor barriers to keep moisture from entering the attic, there are air leaks around ceiling light fixtures, bathroom exhaust fans that allow unwanted moisture into the attic. Moisture condensing on the framing members and the inside of the roof deck can lead to the growth of mold, mildew and rot in the roof deck and framing. A good indicator of moisture problem is rusty roof nails sticking through the roof deck.
Asphalt shingle manufacturers warranties require proper attic ventilation.
Attic ventilation is required in cold environments - it evacuates the warm moist air that heat sources produce. Hot moist air lingering in the attic spaces can condense on the underside of the roof sheathing and rot it out and also causes mold to develop on the interior walls. Cold air in the attic space will not affect the temperature in the adjacent living spaces if properly insulated.
Prevent ice damming in colder climates.
Heavy snowfall can create ice dams that cause a roof to leak along the eaves. An ice dam forms when snow melts over a house's heated spaces and runs down the roof, only to freeze again over the cold eaves. This ice builds up along the eaves and traps snow-melt water, which eventually flows under the shingles into the attic and causes serious damage. Also, the heavy weight of the ice that fills the rain gutters can potentially rip off the gutters (see photo). The best way to prevent ice damming is through proper attic ventilation which will minimize the thaw/freeze cycle.