What is a whole house fan?
A whole house fan is a ventilation cooling system for the home that uses less energy than a traditional air conditioner. This energy-efficient system works by pulling cooler air from the outside of the home to the inside, creating active cross breezes with open windows.
How do whole house fans work?
Since it is normally cooler in the evenings, this would be the best time to turn on the whole house fan. Homeowners simply open a few windows and the whole house fan will cool and ventilate the entire home. When sized properly whole-house fans can exchange the entire air in the home every 3-4 minutes, or 15-30 times per hour.
When running the system for several hours, all the hot air will be pulled out of the mass in the home. This process is called thermal mass cooling. Because the hot air is vented through the attic to the outside, the homestays cooler the next day as well. The home will feel fresh and cool with a whole house ventilation fan.
How to use a whole house fan
To cool the home, homeowners run the whole house fan when it’s cooler outdoors than indoors, which is usually in the early morning or evening time in order to continually circulate cooler, fresh air. You never want to run the system when it is warmer outside unless you want to warm and ventilate your home in the colder months of the year.
Since whole-house fans are used primarily as an alternative-to-A/C cooling system, homeowners will most use their system in the spring, summer, and fall. Instead of A/C, they will open a few windows, activate the “breeze on a switch,” and bring the fresh cool air inside.
When operating the system, homeowners open only a few select windows, 4-6 inches each. This will greatly improve the cooling breeze that is felt. Homeowners must be sure to open windows far enough away from the fans intake in the room that is being cooled in order to feel the breeze. This way, the air will be drawn across the room cooling it in its entirety.
As the fan continues to run throughout the nighttime and early morning, more and more heat is pulled out of the mass in the home, such as furniture, walls, flooring, etc.
When heat is pulled out of the mass within the home, the home becomes truly cooled down. Then, in the morning, before it begins to heat up outside, the fan is turned off, windows are closed and blinds are drawn in order for the home to resist being heated up as quickly. When the homeowner comes home at the end of the day, the house will be cooler and more comfortable because it resisted the heat better than it would have without the whole house fan. This is why the A/C doesn’t have to work as long or as hard. The homeowner will continue to use their air conditioning on occasion when the outside temperature does not cool off enough during the early morning and nighttime hours, however, they won’t need to use it as long or as often.
History of Whole House Fans
Whole house fans are not new! They have been around since the 1960s, and there have been several generational changes to the technology.
There are three types of whole house fans:
- Traditional Whole House Fans
- Mini Ceiling Mounted Whole House Fans
- Advanced Whole House Fans (also known as “ducted whole-house fans”)
Whole house fans do exactly what they claim to do; move a lot of air! Some of the larger systems can move up to 10 times the amount of air that a typical A/C can move.
Whole house fans were first used as an inexpensive way to ventilate a home, cool it down, and save money; instead of turning on the air conditioning unit — which uses a lot of electricity, which costs a lot of money — whole house fans were designed as an alternative to A/C.
Whole house fans originated in the south and east coast of the United States. Because of the modern changes to the technology whole house fans have become really popular in the western states because of the cost of electricity and the hot weather conditions.
What is an advanced whole house fan?
Advanced whole-house fans are whisper-quiet when compared to the traditional whole house fan. And because it’s quiet, people will let it run for hours and hours at a time, allowing the system to do its work!
Advanced whole house fans suspend the motorhead three to six feet away from the ceiling grille with an acoustically lined duct that dampens the sound level. Sound tends to travel in a straight line, and because of this, an advanced whole house fan is suspended at a 90-degree angle to dampen the noise.
Advanced whole house fans also include a barometric pressurized damper system above the grille that seals at an R5 value. This prevents minimal heat and air transfer back into the home. Traditional whole house fans do not have any R-value so there will be a lot of heat transfer between the home and attic.
Advanced whole house fans also have a much smaller ceiling grille. Some advanced whole house fans have very large grilles, but the market leader in advanced whole house fans has grilles ranging from 14 inches by 14 inches to 14 inches by 36 inches and use attractive white egg-crate style aluminum. They are typically removable for easy cleaning and are very quiet.
Advanced whole house fans use ECM (Electronically Commutated Motors) or PSC (Permanent Split Capacitor) motors that are the most energy-efficient and durable motors on the market today. They can be up to 2-5 times more efficient than a traditional whole house fan.
The last objection to a traditional whole house fan is the look of the fan on the ceiling level. Traditional whole house fans are very large, ranging from 24 inches by 24 inches to 48 inches by 48 inches. Most include shutters that rattle very loudly and are very aesthetically unpleasant.