Air Filters Analyzed

It is estimated that a heating and cooling (HVAC) system accounts for almost half of most homes’ energy costs in the US. Choosing the right air filter can dramatically affect your HVAC system’s energy costs, your general maintenance and repair cost, and the air quality in your home. Unfortunately, most homeowners and HVAC contractors choose an air filter based on characteristics such as filter cost and online reviews provided by other homeowners (who are usually uninformed about how to identify a high-quality air filter) while completely ignoring the actual economic and health costs of using that filter. 

For example, a $10 air filter might sound much more appealing than a $100 filter, right? But what if that $10 filter is highly resistive, calls for a monthly replacement, and offers inadequate protection from indoor pollution, while the $100 filter is not nearly as resistive, requires annual replacements, and offers superior efficiency when it comes to airborne pollutants? In other words, using that $10 filter would end up costing you significantly more when compared to the $100 version in this example, in the form of higher energy cost, general maintenance cost, and most importantly, the unquantifiable costs associated with poor filtration performance and indoor air quality.

Since we couldn’t find a reliable article on the matter (other than ConsumerReports.org, which requires paid membership), we decided to test and rate the best-selling and highest-rated filters on Amazon (and the local hardware store) to help our readers choose filters based on the essential characteristics of a central furnace or air conditioner air filter.

How We Test Air Filters

Filterstudy.com tests and rates air filters for homes with forced-air heating and cooling systems based on their filtration efficiency, energy efficiency (resistance), and dust loading capacity. The filters we test are sent to a lab for an ASHRAE 52.2 initial test and tested at 1,280 cubic feet per minute. Our general score is based on the following parameters:

  • Filtration efficiency for particles with a diameter of 0.3-1µm/micron. Generally speaking, those are usually the most dangerous pollutants as they are more likely to get into our bloodstream and lungs undetected and lead to various chronic diseases.
  • Filtration efficiency for particles with a diameter of 1-3µm/micron. Those are usually larger pollutants that can trigger an allergic reaction.
  • Initial resistance, also known as pressure drop, determines the amount of strain a clean air filter applies on your furnace or air conditioner’s fan. The higher the resistance, the harder and longer your system must work to heat or cool your home. For some systems, excessive resistance would be detrimental to the health of your equipment, and in some cases, to the health of your home.

Terms to Know

MERV: An acronym for Minimum Efficiency Reporting Value, a rating system that was developed by ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers). Filters with a higher MERV rating would offer higher efficiencies in all three contaminant categories (E1, E2, and E3). 

MPR: Stands for Microparticle Performance Rating, a proprietary rating system developed by 3M. It rates the filters on the ability to capture airborne particles smaller than 1 micron. 

FPR: Stands for Filter Performance Rating, a proprietary rating system developed by Home Depot. On a scale of 1-10, the higher the number, the better it filters.