Glossary · Heating, cooling & ventilation
MERV rating
Also called: MERV · MERV 13 · MERV 8 · MERV 11 · minimum efficiency reporting value · furnace filter rating
A 1-to-16 rating of how well a furnace or air-handler filter catches airborne particles; higher numbers trap smaller particles.
What it means
MERV comes from a standard test with particles between 0.3 and 10 microns. EPA suggests at least MERV 13 when upgrading, or the highest rating your system's fan and filter slot can handle. Ask an HVAC technician which filter your system can take.
Why it matters in an audit
A better filter is a low-cost indoor air quality upgrade, especially during wildfire smoke, but it only cleans air while the system fan is running.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.