Whole house fans are a very popular choice to cool a home inexpensively. They work by circulating the house with cool air drawn from the outside. They are used in many homes in the US yet their efficiency and cost-effectiveness are a much-debated topic still. Some say these fans are much hyped by marketing while the companies which sell these fans actively try to debunk these claims. What is the truth about whole house fans?
This article is a close analysis of their cost-effectiveness, pros, and cons based on experiences of customers and resources from governmental organizations.
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How much money does a whole house fan save?
You can save 45% on your air conditioning costs by using a whole house fan. Given below is a detailed explanation of how a whole house fan saves you 45% in energy costs by taking a 2000 sq. ft house in Florida as an example.
Let’s jump right into the calculations;
Money saved per day = Cost of air conditioning per day without a whole house fan – (Cost of air conditioning per day with a whole house fan + Cost of operating a whole house fan)
To know the money saved per day, we need to calculate the cost of running an air conditioner with and without a whole house fan, and also the cost of running the whole house fan. Once we know these running costs, the money saved can be calculated by reducing the combined running costs of the whole house fan-air conditioner set up from the cost of running the air conditioning alone.
Cost of air conditioning per day without a whole house fan
Since Florida is in one of the hottest zones in the USA, it will require a central air conditioner of 3 tonnes to reasonably cool a home. The average electricity consumed by such an air conditioner is 3500 Watts/Hour. In the hottest season, air conditioners are run constantly like 20 hours a day. Since the unit rate of electricity in Florida is 11.42 cents, the total air conditioning cost a day is $7.994.
Cost of air conditioning per day with a whole house fan
By using a whole house fan you can limit the use of air conditioning to around 10 hours. Air conditioning will be needed throughout the day but once the outside temperature is cool enough it can be switched off and instead you can start the whole house fan. So this will reduce the air conditioning costs to $3.997.
Cost of running a whole house fan per day
For a 2000 sq.ft home you will need a whole house fan with 6000 CFM rating (Check my post about whole house fan sizing for more details on this). The QuietCool ES-6000 fan is a good choice here. It will consume an average of 300 Watts per hour. So if this fan is run for the rest of the day ie, evening and night time its total operating cost would be only (14 hours x 0.3 x 0.1142) = $0.48.
Note: The air conditioner and the whole house fan shouldn’t be used together as this will remove the conditioned air out of the house.
How much money is saved by the whole house fan?
Now that we found the cost of running, let’s see the cost difference of air conditioning with and without a whole house fan. Using the equation mentioned above;
Money saved per day = Cost of air conditioning per day without a whole house fan – (Cost of air conditioning per day with a whole house fan + Cost of operating a whole house fan)
which is; $7.994 – ($3.997 + $0.48) = $3.497.
That is, with the help of a whole house fan you can reduce air conditioning costs by $3.497 per day. That is around 45% saving!
Verdict: Whole house fans save money
By using a whole house fan in Florida the air conditioning costs can be reduced by 45% per day. But keep in mind that these savings vary across the country based on where you live. If you live in the North East areas a whole house fan may be all you need in the summer.
Pros and cons of whole house fans
If you have been to the website of any companies selling whole house fans you would have seen a long list of the pros of buying a whole house fan. If you re-read through the list you will find that most of the pros they have listed are the same but in different wordings.
Pros of whole house fans
As far as I know, there are only three practical benefits for whole house fans. They are;
- They reduce air-conditioning costs considerably
- They can cool the house within minutes
- They remove the stale air from the house
The main benefit of having a whole house fan is energy saving. As shown above, these fans can reduce air conditioning costs by 45% in some areas during the summer. But during wintertime, they are totally ineffective, you will have to rely entirely on air conditioning.
Whole house fans are very powerful. They create a light breeze inside the house while running. Some fans can do complete air changes within minutes. This quickness cools the house to a comfortable temperature much faster than an air conditioner can.
I hate breathing the stale air in the house. A whole house fan can remove this stale air within minutes. However, air conditioning also reconditions stale air (They don’t ventilate, they just recondition air) so unless you live in an area that doesn’t require air conditioning this is irrelevant.
Cons of having whole house fans;
I can easily cite a few practical problems of having a whole house fan in your house. Here are they;
- They cause heat loss in winter (you can of course winterize it, here’s how)
- Some whole house fans are noisy
- They will bring in unwanted allergens and dust from outside
- They distribute the bacteria and bad odors from all the rooms throughout the whole house
- Increase the humidity in the house
That’s a total of 5 cons against 3 benefits. But numbers don’t matter, the pros of the whole house fans always outweigh the cons. Let me explain what these cons are;
Whole house fans are installed by cutting a hole in the ceiling. The louvers of the fan are not tight enough to prevent conditioned air from escaping through this. There are models like Tamarack HV1000 which come with insulated doors to tackle this problem. However, this still remains a concern for many popular models.
Noise is another con of whole house fans. Since they are installed on the ceiling of the house, and since they are very powerful whole house fans can be annoyingly noisy. This problem can be reduced by using ducted fans. Moreover, the new models are much quieter than the old models.
Another major con of whole house fans is the dust and allergens they bring from outside. These fans do not filter air. If the quality of the air outside your home is worse then having a whole house fan is a really really bad idea. There is also the added risk of pests entering your home through the open windows. So unless you are in an area that has good air quality it is a bad idea to use a whole house fan.
Many companies claim that whole house fans will remove cooking odor and bacteria from the house. Whole house fans are usually installed at the very center of the house so when they work the bacteria and cooking odors will move throughout your house making the conditions even worse. If you have problems with cooking odors the best solution is to use a better exhaust fan in the kitchen, using a whole house fan can be counterproductive.
Using a whole house fan also will increase the humidity inside the house. Air conditioners have dehumidifiers but whole house fans don’t. They will bring the high humid air from the outside filling the house with it. So if you are in a humid area take this into consideration.
Conclusion: Are whole house fans effective?
Whole house fans are totally worth the money if you are living in the right location. If you have hot days and cool evenings with fresh, good air quality then whole house fans can save you a ton of money and make life much easier. If you live in a high humid, dusty area or a pest-infested area these fans may not be the best solution.
