The MERV rating of the air filter provides an easy way for consumers to decide what filter to buy, affects indoor air quality, and has an impact on the cost of operating heating and cooling systems and the lifespan of the filter.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) developed the Minimum Efficiency Reporting Value (MERV) in 1987 with the goal of creating a single standard to make it easier for manufacturers to compare the performance of their products, and to make purchasing air filters easier.
Basically, consumers want to buy the best possible filter for their needs, and air filter manufacturers need an easy way to deliver information to their customers. The MERV rating system ended up being a win-win for the marketplace.
But let’s break all that down. What specifically do these numbers matter?
MERV Ratings Determine Containment Capture
As the MERV rating increases, the polyester fibers that make up the filter media move closer together and increase in number. This allows the filter to capture smaller airborne particles, and stops a greater number of larger particles from passing through the filter media.
Here is a rough breakdown of each MERV rating:
- MERV 8 – Captures 70% of airborne mold spores, dust mites, pet dander, and synthetic chemicals that are 3-10 microns in size; removes up to 35% of dust and other fine particles.
- MERV 11 – Everything MERV 8 captures, plus up to 80% of Legionella, dust, lead dust and auto emissions that are 1-3 microns in size; removes up to 65% of dust and other fine particles.
- MERV 13 – Everything MERV 11 captures, plus up to 75% of bacteria, mucus, cooking oil, smoke, insecticides and paint that are 0.3-1 micron in size; removes up to 90% of dust and other fine particles.
- Commercial – Meets MERV 13 ratings and is suitable for most commercial and industrial applications.
If you are unsure what MERV rating you should buy, we recommend starting with a MERV 11 air filter. These filters balance airflow with airborne contaminant reduction. If the filter meets your needs, in most cases, we suggest you should continue to use MERV 11.
Impacts Lifespan of Filter
The higher the MERV rating, the more contaminants the filter can capture. If indoor air quality is less than ideal, the air filter will load faster than expected and need to be replaced more often.
In some cases, people who used a filter with a lower MERV rating, then later bought a higher rated air filter, found that their filter barely made it past 30 days. While this might seem like the fault of the filter, the real problem is the quality of air being cycled through the air conditioning system.
While your air filter might have been capturing larger particles in the air, many of the smaller particles were getting through. So when you installed the new filter, suddenly all of these microscopic particles hit the filter at once. The good news is that over time, as air quality improves, the filter will last longer.
Higher Ratings Mean Lower Energy Efficiency
If you hold a new MERV 8 filter up to a bright light, then do the same for a MERV 13 filter, you should notice that much less light passes through the MERV 13 filter media. Now imagine this light is the air trying to pass through the filter media.
More light equals greater airflow. A MERV 8 filter will let more air through the filter and will improve energy efficiency, but will also allow increased airborne particles to flow back into the air. A MERV 13 filter will restrict airflow, but will also reduce how many particles flow back into the air.
The amount of air that flows through the air conditioning system airflow directly affects how much air can be heated or cooled in the same amount of time. According to the U.S. Department of Energy, 48% of the average homeowner’s energy consumption goes to heating and cooling, which costs an estimated $115 a month. This means that a higher MERV rating could cost you more money in utility costs each month because you are running the air filter longer, but you would also enjoy higher quality indoor air.
Helps Keep Your Home Clean
Everything that makes your home dirty usually starts as an airborne particle – unless you step in mud before walking through your home. In fact, 80% of dust found inside the home is made up of skin cells.
After you wipe down surfaces so they are free of dust and debris, it makes sense to feel like the home is clean, but chances are there is still a significant number of particle floating around in the air. That’s why air filters are one of the most effective measure against a dirty home.
When the air conditioning system runs, the blower draws in air through the return air vent, pushes it through the filter material that scrubs out many different particles, before it is recirculated back through the home. As a result of fewer particles in the air, fewer particles will settle on surfaces, which may decrease the frequency of cleaning.
Makes Buying Air Filters Easier
When you understand how MERV ratings affect the air filter’s ability to reduce airborne contaminants, and the effect it has on energy consumption, consumers can make smarter choices. From our standpoint at CleanerFilters.com, by being open and honest about this information, we create transparency and improve satisfaction among our customers.