April2017

Debunking the Myths About ATTIC FANS By Steven J. Lang, A.I.A.

The Falcon Group, Engineering, Architecture & Energy Consultants

A s a Registered Architect and building envelope specialist, it is my duty to edu- cate my clients so that they can make informed decisions. Part of my job is presenting facts and information that in some cases may make me unpopular. One of the biggest push backs that I often receive from my clients has to do with my recommendation that they remove their attic fans and replace it with a properly-de- signed, passive ventilation system. Myth – Powered attic fans are the ideal solution to ventilating an attic space. Fact – Properly installed passive ventilation systems provide year round attic ventilation that is particularly important in the Northeast to prevent ice dam- ming and has proven to be more efficient and effective at providing proper attic ventilation than powered attic fans.

At this point in time, you may be scratching your head and thinking “Haven’t I been told that attic fans are good for my attic”? This is probably because over the past 15-25 years, conventional wisdom suggested that attic fans provided superior ventilation. In theory, a powered fan should provide better air flow and ventilation than static openings that provide passive air flow. Based on this line of thinking, motor driven attic fans became quite popular. However, over this time, we have learned a lot more about how these fans actually perform and also gained infor-

mation regarding the unintended side effects that come along with them. The following is a brief summary of the differences between an active attic fan ventilation system compared to a proper passive ventilation system that industry standards and roof shingle manufacturers now prefer.

“Haven’t I

been told that

attic fans are

good for my attic”?

Active Ventilation System In an “active” ventilation system includes a motor driven attic fan that is used to ventilate the attic space. These fans are typically installed high up in the attic CONT I NU E S ON PAGE 22

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