Before considering how effective whole house fans are, it is important to clear up some of the confusion that surrounds them. There are 3 main types of ventilation fans used in homes.They are:
1. The most common kind of ventilation fan is the exhaust fan that is used to remove odors from bathrooms, kitchens and other parts of a house.
2. Attic fans are used to blow warm air out of the attic so that cooler air can be drawn in. Warm air rises to rest on top of cooler air so the attic is where heat collects. By blowing warm air out, the attic is cooled and this, in turn, reduces the temperature in the house itself.
3. Whole house fans are also attic mounted but are much larger and more powerful than attic fans. Because of this, the airflow is far greater so air from all parts of the house is sucked up into the attic from where it is blown out. Cooler air is sucked into the home to replace the air that has been removed and this has the effect of significantly cooling the whole house.
The Whole House Fan Advantage
Once the outside temperature has reached a comfortable level, usually in the morning or evening/night, the whole house fan can get to work. Windows need to be opened (at least 1 in each room) and the fan turned on. The warm stale air from indoors is removed and fresh cooler air is brought indoors. Turning on the fan is just a matter of flipping a switch. The main benefits are:
· With a good whole house fan installed, the need for air conditioning is either removed or reduced to a great extent.
· The coolness is coupled with a flow of fresh air through the home which is healthier and more energizing than the recycled air of air conditioning.
· Because of the amount of airflow they provide, whole house fans bring down interior temperatures faster than air conditioning does. This is what is known as the reduction in sensible heat – the heat that you feel.
· There is another type of heat – latent heat. This is the heat that has been absorbed by furniture, furnishings and other items in the house. These continue to radiate heat from a considerable period of time, which works to counter the cooling effect of air conditioning. The airflow from a whole house fan is continually moving through the house and as it flows over items that have retained latent heat, draws that heat out, bringing down the latent heat quickly so that the house stays cool.
Air Conditioning or a Whole House Fan?