Why MERV 13 Filters May Be Straining Your HVAC & What to Do Instead
- Ava Montini
- Jul 31, 2025
- 3 min read
In the race to improve indoor air quality (IAQ), MERV 13 filters quickly became the default solution. Backed by ASHRAE recommendations and often mandated for LEED, WELL, and government-funded retrofits—particularly in schools and healthcare settings—they offer fine-particle capture down to 0.3 microns.
And the promise is compelling: better protection against smoke, allergens, pathogens, and pollution.
But what happens when a filter built for high capture also comes with high resistance?
That’s the overlooked issue facilities teams across North America have quietly (and not so quietly) been contending with since the industry-wide pivot to pleated MERV 13 filtration. And it’s exposing a critical gap between policy and practicality.
The Unseen Burden
Pressure Drop and System Strain
MERV 13 filters do deliver on filtration performance. But many commercial buildings weren’t designed with the added pressure resistance these filters introduce. Especially older or heritage buildings. This added strain reduces efficiency and risks long-term operational degradation, especially in decentralized HVAC systems like fan coil units, packaged rooftop units, and older RTUs.
Pressure drop, the measure of air resistance across a filter, directly influences fan performance, motor longevity, and energy consumption. As resistance rises, so does the system’s workload. What’s often missed in blanket retrofit strategies is that denser filters may clean more, but they also constrict more.
Common downstream effects include:
Fan overwork, leading to overheating or premature failure
Uneven airflow, resulting in occupant discomfort
Shorter filter lifespan, increasing maintenance load
Higher energy bills, due to compensating fans or longer run times
Peer-reviewed research and government data confirm the operational penalties tied to high-resistance filtration.
According to the U.S. Department of Energy, when HVAC systems are not recalibrated or upgraded during a filter retrofit, increased static pressure can lead to a 20–30% rise in fan energy consumption, as fans work harder to maintain airflow under greater resistance.
A study presented at the ASHRAE IAQ 2013 conference by Zaatari, Siegel, and Novoselac found that rooftop HVAC units experienced airflow reductions of up to 10% when upgrading from MERV 8 to MERV 13 filters, largely due to increased pressure drop across the filter.
In its 2024 Filtration and Air Cleaning Position Document, ASHRAE confirms that increasing filter efficiency (e.g., upgrading to MERV 13 or higher) generally results in higher pressure drop, which can reduce airflow or increase energy consumption—especially in systems not originally designed to accommodate high-efficiency filters.
Despite this, many upgrades were executed rapidly, driven by pandemic urgency and available funding, and not necessarily by holistic HVAC engineering.
Rethinking the Role of the Filter
Not all MERV 13 filters are created equal.
It’s a common misconception that achieving high filtration efficiency must come at the cost of system performance. But advancements in filter design have shown that it’s possible to meet rigorous indoor air quality standards without overburdening HVAC systems.
Instead of relying solely on dense mechanical media that increase resistance, some technologies, such as Blade Air's Pro Filter, use innovative methods, such as electrostatic attraction, to capture fine and ultrafine particles more efficiently.
The benefits of low-pressure filtration approaches are clear:
Significantly reduced pressure drop, preserving system balance and efficiency
More consistent airflow, even in legacy or decentralized HVAC configurations
Lower energy consumption, due to decreased fan effort
Extended equipment life, with reduced strain on motors and fans
Sustainability gains, with designs that prioritize reusability and waste reduction
As building standards continue to evolve, it's worth reexamining whether the filter in use supports both compliance and long-term operational resilience.
Why Low-Pressure Filtration is Gaining Momentum
Facilities professionals today are tasked with a complex balancing act: maintaining high indoor air quality, advancing energy efficiency, extending equipment lifespan, and meeting evolving occupant expectations, all within constrained budgets.
Yet compliance alone isn’t enough. A filter that meets regulatory standards on paper may still introduce performance issues if it exceeds the mechanical limits of an existing HVAC system.
That’s why low-pressure filtration is gaining traction—not as a compromise but as a more strategic path forward.
These next-generation filtration approaches help building operators:
Avoid costly system redesigns or equipment upgrades
Reduce the frequency of service disruptions and maintenance interventions
Advance broader environmental and ESG goals through energy and waste reductions
Most importantly, they restore decision-making power to facilities teams, offering workable options instead of one-size-fits-all mandates.
Rethinking Retrofit Outcomes
If your facility has seen a rise in operational issues following a filtration upgrade, such as higher energy bills, comfort complaints, or premature equipment wear, you’re not imagining it. These are increasingly recognized as widespread challenges linked to high-resistance filters.
But the solution doesn’t necessarily require reengineering your system.
It starts with reexamining the filter itself, and whether it truly supports the way your building functions.
Because in high-performing buildings, air quality solutions should enhance operations, not compromise them.
