A hot attic acts like a giant radiator, transferring heat into your living spaces, sending both utility bills and temperatures soaring. In colder climates, heat build-up in an attic causes snow to melt and run down where it freezes at the eaves, causing destructive ice damming.
Many of today’s houses have insufficient ventilation and air exchange. This causes high humidity levels from everyday activities. The moisture migrates through the ceiling towards the roof where it comes in contact with the cold structure. Here, ice and frost form, causing damage to your roof structure. Additionally, moisture can saturate insulation, promote fungal decay and plywood delamination.

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SOLAR ATTIC FAN COMPARISON CHART
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Solar attic fans offer an environmentally friendly and economical solution to summer time cooling problems resulting from attic heat penetrating your home's insulation. During the summer, attic temperatures can soar to over 150°F, keeping your attic hot throughout the day and well into the night. The higher the temperature of your attic, the less effective your attic insulation will be at stopping heat from entering your home.
Installation of a solar attic fan on your home minimizes the amount of heat entering through the attic by reducing your attic temperature. By minimizing the amount heat entering your home, you will save money on your summer cooling bill and make your house feel more comfortable (see diagrams below).

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The amount of ventilation an attic needs is determined by many factors, but in general the more the ventilation your attic has, the better off you will be. As attic air turnover is increased and fresh make-up air is brought into the attic, the attic temperature will begin to approach that of the ambient outside air temperature, which in turn minimizes heat transfer into your home. As long as your attic has plenty of fresh air make-up ventilation, more airflow through the attic will only increase the cooling performance of your solar attic fan.