Home Air Filters: An In-Depth Guide

Heating and cooling your home accounts for a relatively large amount of your monthly utility bill. Homeowners can increase the efficiency of their HVAC systems in a variety of ways. They can upgrade to a heat pump, improve the airtightness of their building envelope, or invest in high-quality insulation for their attic. However, if your air filters aren't functioning as they are supposed to, both your heating and cooling systems will suffer. Cleaning your air filter to make sure that airflow is not negatively affected is the essential first step. Also, the top air filters on the market today go the extra mile to ensure that you enjoy optimum indoor air quality. 

This complete guide to home air filters explains the many benefits that air filters can bring. How they can improve homeowner health, the contaminants that they help to keep out of our homes, and explain the best air filter options for different types of homes.

What Do Air Filters Do?  

Air filters help to clean and purify the air that your heating and cooling systems circulate throughout the home. Over time, the air inside our homes will gather dust, dirt, pollen, and other types of particulates and contaminants that can negatively affect one's health.

What Can Air Filters Remove From the Air?

Air filtering systems can remove dust, pet dander, pollen, volatile organic compounds (VOCs), odors, bacteria contaminants, and other particulate matter while ensuring unimpeded airflow to increase your efficiency HVAC system.

Can Air Filters Positively Affect Health?

Yes, high-performance air filters can keep your indoor air quality free from pollen, mold, and spores, which are common causes of allergy. Many top air filters (which we will explore below) can also trap finer particles of bacteria and other microorganisms that might cause respiratory diseases. The best home air filters can also catch lint, metal fibers, wood particles, and even some volatile organic compounds (VOCs) that can do damage to your lungs and health in general.

High-performance High-Efficiency Particulate Air (HEPA) air filters, combined with air-purifying plants, will protect the air inside your home. At the same time, a sound mechanical ventilation system can also allow homeowners to invest in an airtight building envelope and high-performance insulation. These building techniques, which are two of the passive house principles, can drastically reduce household energy usage.

How Long Do Air Filters Last?  

Changing the air filter on your mechanical heating and cooling system is vital to maximizing the efficiency of your HVAC equipment. It also ensures the best indoor air quality. Most homeowners choose to use inexpensive fiberglass filters found at virtually any hardware store. If you decide to go this route, you should ideally change your air filters every month. These economical filters can help to protect your HVAC system and indoor air quality. Still, frequent replacement is necessary to avoid impeded airflow and clogging.

Another option is to invest in high-end pleated filters. These filters can last up to six months and are generally at least twice as thick as the standard one-inch thickness on standard filters. High-end pleated filters will undoubtedly cost more, though they will be more effective in preserving the integrity of your indoor air quality.

Do All Air Filters Need to Be Replaced?

Yes. If you routinely forget to change your air filters, a thicker, pleated option might be the best option as they will prolong the replacement periods. However, the densest air filter options (sometimes up to five inches thick) might require renovations on your ductwork or air handler to allow the filter to fit.

What to Look for in the Best Air Filters  

In general, the thicker, the better when it comes to air filter performance. The added upfront cost will most likely pay for itself through longer replacement intervals and increased airflow improving the efficiency of your heating and cooling systems.

You should always prioritize air filter products that are identified as HEPA or high-efficiency particulate air. While HEPA air filters are often included in air purifying systems (check out this Rise article on home air purifiers), they also work as filters attached to mechanical HVAC systems. HEPA air filters offer improved filtering performance by forcing the air through an ultra-fine mesh. The mesh can trap even the smallest air particles, including pollen, pet dander, dust mites, and tobacco smoke.

Some air filter products are advertised as "electrically charged." These filters do not require an electrical connection (despite their misleading name) but are pre-electrically charged, which helps them attract and trap the particulate matter in the air.

Portable Versus Whole Home Air Filters and Purifiers  

For homeowners who are extra concerned about their interior air quality, investing in a home air purifier might be an essential extra step. Unlike the filters connected to your HVAC system, these filters are specifically designed to capture air pollutants and contaminants. Portable home air purifiers are easy to set up, as most of them require you to plug them in and let them run. Whole-house purifiers are not only much more expensive but will also require professional installation. Whole-house air purifiers generally are only effective at removing significant pollutants and contaminants from the air. In contrast, portable options can effectively remove smaller particulate matter more efficiently.

The HEPA filters in portable air purifiers, however, will need to be replaced, usually every six months or so. Whole-house air purifiers, however, generally come with washable filters, which means that you will not have to invest in replacing filters a couple of times per year.

Which Air Filter Is Right for Me?  

Personal considerations should be taken into account in choosing the level of filtration. Does someone have allergies? Is there a pet in the house? Is the house dusty? Does a family member have a compromised immune system? These questions will help you to identify the best air filter for your family.

Homeowners should look for AHAM Verifide products (AHAM Verifide air filters). Details of which filter to choose to address each of these potential issues are described below.

What is AHAM Verifide?

AHAM Verifide filters are tested and rated by third parties and independent laboratories. This certification process verifies the air cleaners' packaging claims about energy, volume, and performance criteria.

Overview of MERV, MPR, and FPR

Other air filter rating systems include MERV, MPR, and FPR ratings, which we briefly explain below.

What Is MERV (Minimum Efficiency Reporting Value)?

MERV ratings depend on a 1-16 scale. This rating system is the domestic and international industry-standard rating system offered by the American Society of Heating, Refrigerating, and Air Conditioning Engineers. 

MERV ratings evaluate an air filter's ability to capture and hold particles and pollutants. The smaller the particles that can be trapped by the filter, the higher the MERV rating will be. Thus a MERV 13 air filter will be able to catch much smaller air pollutants than an air filter rated at MERV 6.  

Air filters with a MERV rating of 6 are capable of catching pollen, lint, and dust. MERV 8 is capable of removing dust mites and mold, and MERV 11 is capable of catching pet dander, smoke, and smog. HEPA filters generally range from MERV 17 to MERV 20.

What Is MPR (Micro-Particle Performance Rating)?

MPR is an air filter rating system developed by 3M. The rating system values range from 300 to 2,800 and reflects an air filter's ability to remove airborne particles between 0.3 and 1 micron. For reference, pollen is a larger air pollutant usually sized between 7 and 50 microns. This rating system only measures the air filter's ability to trap microscopic air particulate matter.

What Is FPR (Filter Performance Rating System)?

FPR ratings measure an air filter's performance on a scale between 4 and 10. This system was created by Home Depot to differentiate the different air filtering technologies they offered. 

The rating system is similar to the MERV ratings mentioned above as they state that air filters carrying a rating of 4 are capable of removing pollen, pet dander, lint, and dust. Air filters with a rating of 9 to 10 are capable of eliminating odors, viruses, smoke, and allergens. Unlike MERV, which is rated by industry professionals, FPR ratings are based on independent lab test results. The rating system is only used in The Home Depot stores as they only test products sold in their stores.

The best air filter technology will largely depend on the type of home you have, the air quality issues you are exposed to, and personal preference. For homeowners looking to eliminate dust, dust mites, pollen, and mold, look for air filters with MERV 8, MPR 600, and FPR 5. For homeowners looking to remove smog, smoke, and coughing and sneezing residue, look for air filters with MERV 8, MERV 11, MPR 1,000-1,200, and FPR 7. For homeowners looking for superior air quality and the removal of bacteria, viruses and all larger particles look for air filters with MERV 13, MPR 1500-1900, and FPR 10.

For standard home construction, regularly replacing the HEPA air filters connected to your HVAC system and running a portable air purifier in strategic rooms can keep your interior air healthy. For passive homes, or homes with a special focus on airtight construction techniques, however, improved air filtering and ventilation technologies might be necessary. HRV or ERV air ventilation technologies are required for these types of homes, both for improved energy efficiency and protecting your indoor air quality.