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Why MERV 13 Filters May Be Straining Your HVAC & What to Do Instead

In the race to improve indoor air quality (IAQ), MERV 13 filters quickly became the default solution. Backed by ASHRAE recommendations...

Ava Montini

Jul 31, 2025

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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.

Why HEPA Filters Matter in Wildfire Season

  • Writer: Jennifer Crowley
    Jennifer Crowley
  • Jun 28, 2024
  • 4 min read

Updated: Jul 8, 2024

Firefighters working on a steep ravine to try and extinguish wildfires
As wildfire seasons become increasingly severe, HEPA filters play a crucial role in maintaining clean indoor air quality and protecting health.

As wildfire seasons grow longer and more intense, especially in regions like Canada and the western United States, maintaining clean indoor air quality has never been more important. At Blade Air, we understand the critical role that HEPA (High-Efficiency Particulate Air) filters play in protecting both residential and commercial indoor environments from the harmful effects of wildfire smoke. This guide explores why HEPA filters are essential during wildfire season and how they can make a significant difference in your air quality and overall health.

Hazy view of wildfire haze across a city scape as seen by two masked individuals on a balcony
The most harmful components of wildfire smoke are particulate matter (PM), since they can penetrate deep into the lungs, enter the bloodstream and lead to various health issues.

The Importance of Air Quality During Wildfire Season

Wildfire smoke is a complex mixture of gases and fine particles from burning vegetation, building materials, and other substances. The most harmful components of wildfire smoke are particulate matter (PM), especially PM2.5 (particles smaller than 2.5 micrometres). These microscopic particles can penetrate deep into the lungs and even enter the bloodstream, leading to various health issues:


  • Respiratory Problems: Persistent coughing, wheezing, and shortness of breath.

  • Aggravation of Asthma and COPD: Increased frequency and severity of attacks.

  • Cardiovascular Issues: Heart attacks and strokes.

  • Eye, Nose, and Throat Irritation: Immediate discomfort and potential long-term damage.

  • Long-term Health Impacts: Lung cancer and complications in vulnerable populations, such as children and pregnant women.


Understanding these risks underscores the critical need for effective air filtration during wildfire season. HEPA filters are designed to capture these dangerous particles, making them indispensable in safeguarding indoor air quality.


Blade Air HEPA Air Purifier
HEPA's superior performance lies in their ability to trap particles as small as 0.3 micrometres with at least 99.97% efficiency.

What is a HEPA Filter?

A HEPA filter is a type of mechanical air filter that forces air through a fine mesh, capturing harmful particles such as dust, pollen, smoke, and bacteria. To be classified as a true HEPA filter, it must meet stringent standards set by the United States Department of Energy (DOE) and effectively remove at least 99.97% of airborne particles as small as 0.3 micrometres (µm).


HEPA Filters: Essential in Wildfire Season

HEPA filters offer multiple benefits that are particularly crucial during wildfire season:


Superior Filtration Efficiency

HEPA filters are renowned for their ability to capture very fine particles, including those found in wildfire smoke. The key to their superior performance lies in their ability to trap particles that are as small as 0.3 micrometres with an efficiency rate of at least 99.97%. This ensures that even the smallest and most harmful particles are removed from the air:


  • Effective Against PM2.5: Given that PM2.5 is the most dangerous component of wildfire smoke, HEPA filters are highly effective in providing protection.

  • Captures a Range of Pollutants: In addition to smoke particles, HEPA filters also capture other pollutants such as pollen, dust mites, and pet dander.


Health Benefits

The health benefits of using HEPA filters during wildfire season are significant:


  • Reduces Respiratory Symptoms: People with allergies, asthma, and other respiratory conditions experience fewer symptoms.

  • Decreases Cardiovascular Risks: Lower exposure to airborne particles reduces the risk of heart attacks and strokes.

  • Improves Overall Well-being: Cleaner air contributes to better sleep, productivity, and mental clarity.


Reinforcing HEPA Filters with Activated Carbon

Many HEPA air purifiers also include activated carbon filters. While HEPA filters are designed to capture particles, activated carbon filters are effective at removing gases and odours such as volatile organic compounds (VOCs) that are released during wildfires. This combination of filters provides comprehensive air cleaning:


  • Odour Removal: Activated carbon filters eliminate the smoky smell associated with wildfires.

  • Chemical Filtration: They remove harmful chemicals such as benzene and formaldehyde.


How to Choose the Right HEPA Air Purifier

When selecting a HEPA air purifier, consider the following factors to ensure you are getting the most effective protection during wildfire season:


  1. True HEPA Certification: Ensure the air purifier uses a true HEPA filter, meeting DOE standards for filtration efficiency.

  2. Clean Air Delivery Rate (CADR): Look for a high CADR rating for smoke. This measures the air purifier’s efficiency in cleaning air.

  3. Coverage Area: Match the air purifier’s coverage capacity (in square feet) to the size of your room or home area.

  4. Filter Longevity and Ease of Replacement: Consider the lifespan of the filters and their ease and cost of replacement.

  5. Noise Levels and Energy Efficiency: Choose a model that operates quietly and efficiently.


Using HEPA Filters: Best Practices

Illustrated image of an air purifier placed on a central location showcasing its air circulation capabilities
Strategic placement is important. Place the air purifier in the room where you spend the most time. For homes, this is often the bedroom or living room with a clear path for air to flow.

To maximize the effectiveness of HEPA air purifiers, follow these best practices:


  1. Strategic Placement: Place the air purifier in the room where you spend the most time. For homes, this is often the bedroom or living room.

  2. Continuous Operation: Keep the air purifier running 24/7 during wildfire season to maintain clean air.

  3. Regular Maintenance: Replace HEPA and activated carbon filters according to the manufacturer’s recommendations to ensure optimal performance.

  4. Seal Your Home: Use weatherstripping, door sweeps, and other measures to prevent outdoor air from entering your home. This reduces the burden on your air purifier.

  5. Create a Clean Air Room: Designate a specific room with minimal outdoor air infiltration and use a high-efficiency air purifier to maintain air quality.


Blade Air: Your Partner for Clean Air

At Blade Air, we are dedicated to providing advanced air purification solutions that meet the highest standards of performance and reliability. Our flagship products, such as the HCFM-1 Portable HEPA Purifier, Pro Filter with Advanced Electromagnetic Filtration, and HEPA+ Filter, offer unmatched protection against wildfire smoke and other airborne contaminants.


Advantages of Blade Air HEPA Air Purifiers:


  • High-Efficiency Filtration: Our true HEPA filters effectively capture 99.99% of particles at 0.3 micrometres.

  • Comprehensive Coverage: Suitable for both residential and commercial spaces, providing wide-ranging protection.


As wildfire seasons become increasingly severe, HEPA filters play a crucial role in maintaining clean indoor air quality and protecting health. By investing in high-quality air purification systems and following best practices, you can significantly reduce exposure to harmful pollutants and ensure a healthier environment for yourself and your loved ones.

Explore expert insights, stay up to date with industry events, and gain a deeper understanding of the cutting-edge developments that are revolutionizing the indoor air quality landscape within Blade Air's comprehensive Insights Hub.

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