While fiberglass air filters will do the job in the most basic way, in most cases, pleated air filters are much better. They can filter out the smallest particles, which is important for people with sensitivity in the air. They are less likely to clog in a short time and can last up to 90 days. And then, to make sure your filter continues to avoid the bad stuff, follow a three-month replacement schedule for a pleated air filter (and about twice as often for fiberglass filters).
Various particles floating in the air are trapped in the fabric of a pleated filter that would pass directly through ordinary fiberglass air filters. An effective air filter combines filtering efficiency with airflow to create a product that is effective at removing particles from the air, but that does not create unnecessary demand on your HVAC engine by blocking the passage of air. Because of their efficiency, sustainability and cost-effectiveness, pleated filters outperform fiberglass filters in almost every category. Perhaps the best news of all is that you don't have to spend much more money on them than on a fiberglass filter.
These filters provide minimal filtration when they are new and, once they have collected any amount of dust, their efficiency is further reduced. So the answer to the question is technically yes, fiberglass filters allow better airflow, but the difference is largely irrelevant to the HVAC system and its health and efficiency. From sizes to types, grades and more, here's everything you need to know about air filters. Pleated air filters fold into an accordion shape to allow for a larger surface area to capture more particles in the air.
Fiberglass filters are at the farthest end of that spectrum, providing near maximum airflow at a trade-off that delivers near zero filter efficiency. I use a Honeywell 4 MERV10 FC40R1078 pleated filter that has a lip and fits in many return ducts designed for standard 1 filters. For reference, a pleated filter of only a MERV 8 rating filters at least 75% of particles between 3 and 10 microns. As stated above, fiberglass air filters are commonly referred to as “rock traps” because of their abysmal ability to, you know, filter things out.
MERV stands for Minimum Value of Efficiency Reports and is a standard for measuring the number of air filters that can trap and trap fine particles in the air.