The main difference between attic fans and whole house fans is their working. An attic fan is used to remove hot air from the attic to the outside whereas a whole house fan is used to move cool air from the outside of the house into the living areas. An attic fan is used to lower the attic temperature while a whole house fan is used to lower the temperature of the living spaces.
Both types of fans work to lower the temperature of the house. Whole house fans were once called attic fans but not anymore. Other than their working there are some other differences between these two types of ventilation fans. Here is a quick comparison of the attic and whole house fans.
|Attic fan||Whole house fan|
|Removes hot air from the attic to the outside||Brings cool air from the outside to living areas while removing the hot air into the attic|
|Smaller size and power rating compared to whole house fans||Larger in size and power rating|
|Easy installation||Installation is not as easy as that of attic fans|
|Installed on the roof or gable||Installed on the ceiling|
|Quieter operation since it is installed away from the ceiling||Usually noisy if installed on the ceiling|
|Costs less||Costs more|
|Not proved to be Energy efficient or cost saving.||Reduces air conditioning costs by 50 to 90%|
|No effect of home resale value||Increases home resale value|
|Most effective at the hottest time of the day||Most effective when the outside temperature is lower than the home temperature.|
|Can be used along with air conditioning||Cannot be used along with air conditioning|
Attic fans are smaller in size compared to whole house fans
Since attic fans are used to remove air from the attic they don’t require very high air flow. The approximate CFM calculation of an attic fan is 0.7 x the square foot area of the attic. So for an attic with an area of 1000 sq.ft the CFM needed for the attic fan would be 700 CFM.
On the other hand, the CFM of whole house fans needs to be considerably higher to cool the living areas. A general calculation would be 2.5 x sq.ft area of the house. So a house with 1000 sq.ft area will require a whole house fan of 2500 CFM. Experts require that whole house fans should do 3 to 6 air changes per hour for effective cooling. Since their CFM ratings are much higher than attic fans they are also bigger in size and have more power consumption.
Attic fans are slightly easier to install
Attic fans are relatively easier to install than whole house fans. If you have enough gable vents all you have to do is fit the attic fan on the vents. Roof top installation is a bit more difficult since you will have to cut a hole on the roof and properly insulate it after the installation.
Whole house fans are installed on the ceiling between the attic and the living areas. You will need to cut a hole on the ceiling, and make sure that everything is air tight after the installation.
Attic fans are quieter than whole house fans
Since attic fans are installed on the gable or the rooftop which are away from the ceiling the noise from them is hard to reach the living areas. As a whole house fan is installed on the ceiling of the house the noise it makes will reach you much easier. Since whole house fans are also much powerful they will make relatively more noise.
Today there are many whisper quiet models available for both type of fans so my advise is not to worry much about noise.
Attic fans are relatively cheaper
Considering that whole house fans need to be bigger and more powerful compared to attic fans to cool the same area the former are going to be definitely expensive. The cost of attic fans range from 80 to 400 USD whereas that of whole house fans range from 150 to 500 usd.
Whole house fans are energy efficient and they cut air coditioning costs
Whole house fans are proven to be energy efficient and they help to reduce air conditioning costs by 50 to 90%. This reduction depends on the state you live in. If you are living in a hot location (temperature wise) then you may be able to cut costs by 50-60%. In colder areas you can save way more on air conditioning costs.
Attic fans on the other hand are not proven to be either energy efficient or cost cutting. They help in reducing attic temperatures but there is still no evidence that they are cost effective.
Whole house fans increase the resale value of homes
In the right climate, having a whole house fan can increase the resale value of your home. By right climate I man moderately cool climate like in the North West of USA. In those areas a whole sale fan can reduce air conditioning costs significantly during summer.
But attic fans, since they are not proven to be cost efficient, doesn’t affect home prices. Having an attic fan won’t do any harm but as far as I know they don’t play any role in the resale value of a home.
Attic fans are effective when it is hot outside while whole house fans are most effective when it is cooler
Attic fans are meant to cool the attic by circulating air through it. During peak temperatures, an attic can be unbearably hot. If there is no air circulation then the temperatures in the attic will stay above what is outside. Therefore running an attic fan at peke temperatures will help to cool down the attic very fast.
Whole house fans are most effective during night and evenings when the outside temperatures are cooler. As whole house fans draw this cool air and circulate them through the living spaces the temperature inside the house will fall quickly.
Attic fans can be used while the air conditioning is runing but whole house fans cannot
Provided there is no air leakage between the attic and the living spaces an attic fan is perfect to work with air conditining. By reducing the temperature of the attic these fans help to reduce the load on air conditioners, slightly.
Since whole house fans suck air from the house into the attic it cannot be used along with air conditioning. These fans are to be used before you kick on your air conditioner. When you run the whole house fan it reduces the temperature of the whole house so an air conditioner does not have to work very hard.
Attic fan or whole house fan – which one do you need?
Attic fan and whole house fan fulfill different requirements. Hence one cannot replace another. Using both of them together is a good idea. However, if you plan to buy only one of those I recommend you go with a whole house fan.