As we progress through the COVID-19 pandemic and begin to repopulate indoor spaces, many people are now focused on improving air quality. You may notice restaurants, offices, and transit agencies trumpeting their installation of “MERV-13” air filtration. If you weren’t familiar with the term “MERV” before, get ready—MERV ratings are about to become an important part of everyday indoor life. Here’s what you should know about MERV ratings as a small business owner, manager, or all-around decision maker.
What Does “MERV” Stand For?
Maybe you prefer the term “furnace filter,” “AC filter,” or “HVAC filter.” Either way, manufacturers must assign a rating to the matrix of fibers that keeps airborne particles from clogging your furnace and spreading through your system. The MERV system, which stands for “minimum efficiency reporting value,” is one of several rating systems for HVAC capability. The minimum efficiency of a filter is the baseline of its capacity for collecting particles. The higher the MERV number, the smaller its minimum particle arrestment. At MERV-1, the lowest rating, a filter will successfully capture up to 65 percent of most lint but fail to catch anything smaller.
What Do Ratings Mean?
As a MERV rating increases, the standards for achieving that rating get higher. At MERV ratings 1 through 7, measuring a filter’s efficiency focuses on particles ranging from 3-10 microns in width. To achieve MERV-8, manufacturers begin to measure average arrestment of particles 1-3 microns, and at MERV-11 and above, testing must prove efficiency against 0.3-1.0 microns. Manufacturers test filters against increasingly smaller particles, from pollen on the low end to tobacco smoke and bacteria on the high end.
Which Rating Should I Look For?
Different HVAC systems and environments call for different levels of air filtration. In the wake of the pandemic, the aforementioned MERV-13 filter is making waves. MERV-13 is typically the upper limit of filtration available to non-scientific and non-medical HVAC systems, with over 50 percent effectiveness against particles in the 0.3-1.0μm range, such as bacteria, talcum dust, and some viruses. If your place of business will see heavy foot traffic, you may want to allay concerns by opting for this level of filter.
When High Is Too High
That being said, what you should know about MERV ratings is that a higher number isn’t always better. Not every system is built for high-efficiency filtration. Residential HVAC systems aren’t always built to specifications that can handle the restriction on airflow, which can wear down the HVAC system. If your unit does not specify a MERV range, consult a technician.