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July 31, 2018

How many attic fans does one home need?

solar attic fan

When making a large purchase, it is very important to understand just how many products are needed. If that number exceeds the one that the buyer had in his head then the entire sale may become nonexistent. If a buyer comes into a situation where they believe they will only need one thing, in this case an attic fan, then suddenly realizing their home may need more could be a shock that leaves a bad taste in their mouth.

As with most things, how many attic fans a home needs is reliant on something else, in this case, the size of the home itself. An attic fan is a pretty self explanatory machine as it fans the attic. Specifically, it takes the hot air out of the attic and pushes it back outside. This is important for a home because the attic is the hottest part of a home.

According to Fast Facts, “Attics can reach temperatures of 150 to 160 degrees F during a summer day, although outside air temperatures are only 95 to 97 degrees F. The cooling load for a home air conditioner depends on the difference in temperature between the inside and outside air, and reduction of attic temperatures from 155 degrees to 105 degrees F will result in a significant reduction in cooling load.”

An attic fan is able to achieve this significant reduction in cooling much more efficiently than an air conditioner. Fast Facts also has a handy equation to determine just how much ventilation is required in a home “Calculate the required summer ventilation rate by determining the volume of attic space and dividing by 2. This will be the cfm (cubic feet per minute) of ventilation air needed. The volume is determined approximately for a rectangular house by multiplying the height from the ceiling to the peak/ridge (H) times the width of the house (W) times the length (L) and dividing by 2 — ( H x W x L / 2 ). For a gable roof, this will be reasonably accurate. For a hip roof house, the volume will be overestimated but adequate.”

So, with cooling of the attic being the main objective then the number of attics a home has is an important factor when buying an attic fan. If you have a multi-layered home then multiple attic fans may be necessary. But, for standard homes, just one attic fan will work effectively.

Most common homes have just one large attic where having a single attic fan would be perfect. When someone is looking to purchase an attic fan, they may be worried about having to buy multiple of the same product, however, for most people, just one attic fan works perfectly fine and will significantly cool the entire home as the attic is rapidly cooled down from dangerous temperatures like 160 degrees F.

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