When it comes to filters, not all options are created equally. You could say there are three main types of filters: cheap, moderately priced and expensive. But this would be factoring in only one component – sticker price – without taking a good, hard look at construction quality, useful life, effectiveness in filtering out air toxins and allergens and other even more important attributes.
In actuality, there are four main types of air filters (with a myriad of smaller variations in between them). Different filters are designed to do different kinds of jobs in different ways and with varying degrees of success. For the cleanest indoor air regardless of what is going on outside, you want to be sure you pick the most effective filter for the job, which is what this post will teach you to do!
First, A Word About MERV
Before we launch into a discussion of filter types, there are two acronyms you will want to keep in mind.
- MERV. In the commercial HVAC industry in particular, MERV (Minimum Efficiency Reporting Value) is the efficiency standard used to categorize filter types.
- IAQ. MERV measures IAQ (Indoor Air Quality) between different types of filters.
As more is being learned about how filters interact with indoor air to clean and improve quality, filter construction continues to improve accordingly. This is good news for homeowners and employers alike!
Filters: A Definition
As you shop for filters, you may notice lots of additional acronyms (plus a great deal of fancy language) touting the advantages of one versus another. While there are certain undeniable advantages that can be realized based on material type, quality of construction and matching the right filter with the right air quality issue, at their essence filters are really pretty simple.
A filter is essential permeable (porous) material stretched over a frame in a way that the air itself can pass through but particulates such as pollen, dust, mites, dander and toxins will get caught in the material and will not pass through.
4 Main Types of Filters
The first three types are the most common filter types you will see on the market today for use in residences and commercial buildings. Each has different benefits and strengths.
- Fiberglass. Fiberglass filters are the most commonly used filter type in homes and workplaces today. Designed to be disposable, fiberglass particles overlay a supportive metal frame. The fiberglass particles trap the toxins and particulates as they pass through with the air.
- Polyester (Pleated). Pleated polyester filters are also disposable and are designed to be a slightly more robust and effective alternative to regular fiberglass filters.
- HEPA (High Efficiency Particulate Arrestance). HEPA filters have enjoyed a steadily rising popularity because of their proven ability to trap particulates, allergens and toxins down to a very fine level. HEPA filters are recommended in any home that includes pets or smokers. HEPA filters that meet U.S. Department of Energy standard STD-3020-97 are guaranteed to filter out 99.7 percent of ALL particulates that are at least 0.3 microns in size (for comparison’s sake, a human red blood cell is 5 microns in diameter and bacteria is anywhere from .2 to 3 microns in size.).
- Washable. As they sound, washable filters are designed to be washed and reused. These are not so common today except in industrial facilities where the dust and particulates tend to be larger and coarser. The odd and interesting advantage to washable filters is that dust buildup along the outer edges actually improves the filter’s overall filtering ability.
How to Choose the Right Filter for Your Air Quality Needs
So now you are aware that, while the basic concept of an air filter is really very simple, there are a number of different design options to choose from. So how do you know what type of air filter to choose?
There are four components that should be considered when choosing an air filter:
- Budget. Some filters are pricier than others. If budget is an issue, then you may need to pick your battles when it comes to premium filters (such as installing a basic air filter for the main HVAC system but then putting in an additional smaller HEPA filter to further clean the air in your asthmatic child’s bedroom).
- Outdoor air quality. Some areas just have cleaner outdoor air than other areas. For example, if your home or workplace is near a big energy plant or industrial facility, you may want to opt for more robust indoor air filters.
- Indoor air quality. Along with pets, smokers, candles, air fresheners and other potential toxin generators comes a natural decrease in indoor air quality. The more of an impact you expect your family to have on your own indoor air, the more robust you will want your filter to be.
- Allergies in the family. If you or another family member suffers from allergies, asthma or any type of breathing issue, you may want to consider bringing in a higher grade of filter, such as HEPA filters, to keep your indoor air cleaner.
What to Look for When Purchasing Filters
In general, most experts will recommend that you change your HVAC system air filter at least once each month and more frequently if there are particular air quality issues (such as smoking in the household).
So each year you will consume at least 12 air filters for your main HVAC system. Then you may need additional HEPA filters for bathrooms, bedrooms or basements. Cost-wise, it may help to purchase in bulk and get a quantity discount for disposable filters. Or you may want to opt instead for washable HEPA filters that you can wash and reuse many times. Finally, be SURE to measure the height, width and length of your filter before you purchase!
