Minimum Efficiency Reporting Value And What Is It Exactly?

Energy efficiency concept with energy rating chart

If you heard of MERV before but did not know what exactly it was, here is a good place to start. We hope that after this article you will not just have a vague idea, but you will start using this technology in your own home. MERV is something that cannot just account for a better price of your property on the market and increase its real estate value, but it can increase the quality of your life in general. Read more about it and find out things you did not know, also if you have any questions or comments, make sure you leave a comment or contact us through email.

Pre-filters are one of the most misunderstood components of an air handling system. Filters are the first line of defense in air conditioning units. What is installed determines air quality and energy costs.

Since there are many types of systems, the pre-filter section will determine what type of filters can be used. Typically, in fan coils, heat pumps and package units, the pre-filter section will only accommodate a 1- inch filter. Since lower air flows are in these types of systems, throw away fiberglass filters are sometimes used. This type of filter has a little restriction. However, in reality, the coil now becomes the filter as this type of filter has a MERV (Minimum Efficiency Reporting Value) rating of 1-4 and a capture rate of fewer than 10 microns. Regarding contaminating retained in the filter, it is like comparing catching basketballs to catching marbles. So the very large and very small particles will blow through the filter and plug up the coil. This type of filter would be the least expensive regarding cost and the most expensive regarding energy since impacting the coil, with so much contamination, will reduce heat transfer.

Minimum Efficiency

These filters have options, making them a better choice. Throw away filters have more media in a pleated style, will be a MERV 5-8 and have a capture rate of 80 to 95 percent on 3 to 10 micron. These filters have the capability of protecting the coils and delivering better air to the occupied spaces.

A study conducted by HLW International, LLP, an architectural and engineering firm, found that employee productivity levels are influenced by the cleanliness of the office in which they work. Making choices on pre-filtration has a lot of impact on the final result of employee performance and the cost to run air conditioning systems.

Rule of thumb, use a filter with a pleated surface area and one that is high capacity. This increases the life of your air conditioning unit and lowers pressure drop, in turn saving energy. A MERV 8 is preferable. The same rules apply to using 2-inch and 4-inch pleated filter if the systems you are using have the channels or frames for those.


To get maximum value, the more media and pleats per lineal foot are what should be installed. They may cost a little more. However, the payback is better than lesser media filters.

There are other ways to cut cost and improve air quality with filters. Systems with filter sections that use a deeper, in-length filter that can be upgraded to a pocket filter of higher efficiency are good choices. These types of filters have more media and less pressure drop and can be upgraded to higher MERV ratings. Using a MERV 12 will prolong the life of the final filters that may be in the systems.

We would love to hear from you and get feedback. So, what do you think of MERV?