Air purifiers can improve the air quality of the whole house. But what if you have an enormous 10,000 sq ft mansion; will a single air purifier be enough?
Of course not. There is some confusion when it comes to air purifiers. In general, these are two kinds of homeowners:
- The ones with small homes asking asking ‘Do I need an air purifier in every room?’.
- The ones with big homes asking ‘How many air purifiers do I need?’.
In short, it all comes down to 2 factors:
- Square footage of your home. This correlates to the amount of air that needs to be cleaned.
- The airflow (or capacity) of an air purifier. This correlates to how much air can an air purifier clean.
You don’t necessarily need an air purifier in every room. If you check out the list of the best air purifiers here, you can see that most of them can purifier the air in 500 sq ft or so.
If you have a living space with a 12×12 bedroom, 15×10 kitchen, and 14×14 living room, a single air purifier might just be enough. You can even move it around from room to room in order to increase indoor clean air circulation.
Of course, if you have a home bigger than 500 sq ft, you will need more than 1 air purifier if you want clean air in every room properly. Another option would be to invest in a big and powerful whole-house dehumidifier such as Aprilaire 5000 Electronic Air Cleaner which can clean 3750 sq ft by itself.
Let’s look at how to calculate how many air purifiers you need. If you dislike a bit of math, you can check the table of how many air purifiers you need for different home sizes at the end.
How To Calculate If You Need Additional Air Purifiers?
Let’s say you have a 2,000 sq ft. You would like to use air purifiers to improve indoor air quality. How many air purifiers do you need?
If you use standard purifiers with 500 sq ft coverage area, you would need 4 air purifiers.
Let’s see how the number of air purifiers can be calculated. We need to take into account how much air is in our house and how fast can an air purifier clean that amount of air.
Calculating The Amount Of Indoor Air
Let’s calculate the volume of indoor air. The equation we use is:
Volume (indoor air) = Indoor area (in sq ft) x Ceiling height (in ft)
For example, if we have a 1,000 sq ft home with 8 ft ceiling height, we can calculate the total volume of air like this:
Volume (indoor air) = 1,000 sq ft x 8 ft = 8,000 ft3
So we’re dealing with 8,000 cubic feet of air. If we want to properly clean that amount of air with an air purifier, we need to clean it about 4 times every hour. We talk about 4 ACH or Air Changes Per Hour. You can read more about how to calculate ACH here.
Essentially, that means that we need to clean 4 x 8,000 ft3 = 32,000 ft3 of air per hour. Now, let’s see what amount a single air purifier can purify per hour.
Capacity Of An Average Air Purifier
An average air purifier has an airflow of 200 CFM. That means that it cleans 200 cubic feet of air per minute. Mind you, this is a per-minute number. In order to figure out how many cubic feet a unit can handle per hour, we need to multiply that number by 60. We get 200 CFM x 60 = 12,000 cubic feet per hour.
One purifier can properly clean 12,000 ft3 per hour. But to clean 1,000 sq ft home, we need to clean 32,000 ft3 of air per hour. That means we’ll need more than 1 air purifier.
Total Number Of Air Purifiers Needed
Well, how many purifiers would that take? Let’s calculate:
If 1 air purifier cleans 12,000 ft3 of air, 2 of them will clean 24,000 ft3. But we need to clean 32,000 ft3. Obviously, we would need 2.5 air purifiers.
Here is how you can calculate this is you know the amount of air that needs to be cleaned per hour and the performance of an air purifier:
No. of air purifiers = Amount of air to be cleaned (in ft3/h) / Air purifier airflow (in ft3/h)
In our case, we calculated the number of air purifiers for 1,000 sq ft home like this:
No. of air purifiers = 32,000 ft3/h / 12,000 ft3/h = 2.5 air purifiers
Table Of How Many Air Purifiers Do You Need For Different Home Sizes
For houses bigger than 800 sq ft, it makes sense to invest in more than one air purifier.
Below you’ll find a table of how many air purifiers you need for different home sizes. Just be aware that these numbers are calculated based on an 8 ft height ceiling and 200 CFM air purifier airflow.
We use a different number of air changes per hour (ACH). The recommended ACH for the cleanest indoor air is 4; of course, you’ll need more air purifiers to achieve this.
|Coverage Area||Air Changes Per Hour (ACH)||Number Of Air Purifiers Needed|
|800 sq ft||4||2|
|800 sq ft||2||1|
|800 sq ft||1||1|
|1,200 sq ft||4||3|
|1,200 sq ft||2||2|
|1,200 sq ft||1||1|
|1,600 sq ft||4||4|
|1,600 sq ft||2||2|
|1,600 sq ft||1||1|
|2,000 sq ft||4||5|
|2,000 sq ft||2||3|
|2,000 sq ft||1||2|
|2,400 sq ft||4||6|
|2,400 sq ft||2||3|
|2,400 sq ft||1||2|
|2,800 sq ft||4||7|
|2,800 sq ft||2||4|
|2,800 sq ft||1||2|
|3,200 sq ft||4||8|
|3,200 sq ft||2||4|
|3,200 sq ft||1||2|
As you can see, the number of air changes per hour (ACH) we want significantly impacts the number of air purifiers we need.
For example, for a big 3,200 sq ft home 2 air purifiers are enough if we can satisfy ourselves with 1 air change per hour. However, if we want to achieve the recommended 4 air changes per hour, we would need 8 air purifiers.