Preparing commercial buildings for tomorrow’s pandemics and everyday IAQ.

Advanced Air Filtration Technology Saves Costs, Sells Buildings.

This Article appeared in the National Association of Realtors on April 7, 2025

Commercial & Investment Real Estate, Coronavirus, Risk Management, Environmental Issues

The COVID-19 pandemic raised the profile of building filtration systems able to screen out airborne particles. Since then, wildfire smoke from a tinder box of drought-stricken forests across North America have added to commercial building indoor-air quality (IAQ) concerns. Recent wildfires proved that smoke can waft across hundreds of miles and infiltrate the indoor breathing zones of even the most tightly constructed buildings.

Wildfire smoke spells bad news for commercial buildings that are mandated to continuously add 10% to 20% fresh outdoor air into their HVAC supply air as mandated by IAQ codes such as ASHRAE Standard 62.1, “Ventilation and Acceptable Indoor Air Quality.” Ironically, fresh air building codes designed to dilute or replace indoor air contaminants are actually adding unacceptable amounts of pollution during wildfire smoke periods.

However, with the advent of advanced IAQ technology, such as non-thermal plasma-based filtration, commercial property owners and managers can promise tenants a healthier future. They can also set themselves apart by marketing their property as adhering to the safest air quality standards.

The Dangers of PM2.5

Smoke and biological contaminants have different makeups. Thus, they require different mitigation measures.

Wildfire combustion smoke consists of small particles, gases, and water vapor. Water vapor makes up most of the smoke. The remainder includes carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), irritant volatile organic compounds (VOCs), air toxins, and very small particles. By the time wind currents distribute wildfire byproducts hundreds of miles, the gases have dissipated. Consequently, the remnants are predominately particles in the Particulate Matter 2.5-micron (μm) range, which are harmful to human respiratory systems.

PM2.5 floats almost perpetually within commercial and residential spaces. PM2.5 can be biological or just simple sub-micron dust. Direct sunlight can sometimes highlight PM2.5 particles, but otherwise they are invisible. These potentially lethal floaters, when inhaled by occupants, are small enough to flow through the lungs and into the bloodstream, where they can eventually join triglycerides, cholesterol and other accumulations of particles that can cause heart disease, or worse yet, a fatal heart attack.

Particulate Filtration

Commercial building HVAC equipment, especially older systems, may not have dense enough air filter media to capture PM2.5. For example, a Minimum Efficiency Reporting Value (MERV) 13 filter can trap 50% of .3 to 1.0-μm; 85% of 1.0 to 3.0-μm; and 90% of 3.0 to 10-μm particles. A 90% or higher entrapment is acceptable; however, many older HVAC filter systems use standard MERV 11 and MERV 8 media filters, which trap only 65% and 20% of PM2.5, respectively.

Upgrading to MERV 13 is possible, but only for HVAC systems that can handle the increased static pressure, or airflow resistance. Filters such as high efficiency particulate air (HEPA) filters (rated MERV 17 to 20) capably entrap microscopic contaminants but are not usable in HVAC systems that weren’t designed for the inherent static pressure drops of denser media. HVAC systems converted to HEPA filters require more fan horsepower and possible ductwork retrofits.

Facility owners looking to upgrade to higher efficiency HVAC filters, such as MERV 13 or HEPA, should check with the manufacturer or the system’s design engineer.

Besides the inherent static pressure drops and upfront equipment capital costs, a disadvantage of particulate filtration is the high cost of periodic HEPA filter media replacement. During a pandemic, replacing HEPA filters also requires hazmat-certified service techs, vehicles and landfills. Furthermore, the energy consumption from larger fans required to offset anticipated static pressure losses can increase building operational costs.

Disinfecting Biological Contaminants

HEPA filters capably entrap viruses, allergens, mold, mildew and other biological contaminants, but the captured microorganisms can survive and even replicate while residing in the filter. ASHRAE Standard 241 recommends filtration that disinfects or neutralizes these contaminants. The most popular methods are ultraviolet germicidal irradiation (UVGI), bipolar ionization and non-thermal plasma.

UVGI technology isn’t new and has been used to disinfect air for decades. It employs ultraviolet waves, the same waves produced by the sun. There’s no doubt UV-C lamp systems, which are placed in the HVAC system near the evaporator coil or in ductwork, effectively disinfect biological contaminants especially those that pass two UVGI effectiveness test standards:

ANSI/ASHRAE Standard 185.1: UVGI lamps for in-duct irradiation of airborne microorganisms
ANCI/ASHRAE Standard 185.2: UVGI lamps for in-duct surface irradiation

The proof is visible. Air conditioning evaporator coils outfitted with UV-C lamps remain clean over the HVAC system’s lifespan and often require no periodic cleaning, which cuts coil maintenance and mold removal costs.

However, UV-C lamps require replacement every one to three years, which is costly, and they are unable to capture and remove particulates from the airstream.

Ionization, another disinfection filtration method that’s sometimes referred to as bipolar ionization, creates airborne ions from a generator installed inside the HVAC system airflow. Positively and negatively charged ions are generated from an ionizer and distributed throughout the occupied space via the HVAC system ductwork. Once in the occupied space, they electronically attach to particulates to enlarge them. Thus, contaminants that once flowed through MERV 8 or MERV 13 filters are now larger via agglomeration and become entrapped.

The disadvantage is that the ions dissipate in just a few minutes inside their destination space. The ions can also prematurely dissipate in long commercial ductwork runs. The ionization process also generates ozone, which the EPA has determined as a respiratory health issue.

Filters That Disinfect and Collect Particulates

Recent advancements have combined disinfection of biological contaminants with particle collection. One technology, non-thermal plasma-based filtration, was recently featured in the December issue of the peer-reviewed ASHRAE Journal. This newer technology is the size of a one-inch-thick media filter, available in various widths and lengths to fit most HVAC filter rack sizes. It’s called The Aireshield. The UL2998-validated technology creates a high-voltage plasmic electric field in the HVAC airflow that kills or alters biological contaminants’ ability to replicate.

Besides electrical disinfection, non-thermal plasma-based filters electrostatically charge airstream contaminants. The polarity electrically attaches the ions to each other and contaminants. Therefore, contaminants that were too small for media filter entrapment are now enlarged by the agglomeration of negatively and positively charged ion attraction. The enlargement prevents their free flow through MERV 8 and MERV 13 media filters, and they perform like MERV 13 and MERV 16 filters (respectively), but without the energy- consuming static pressure increases of those denser filter medias.

The cost savings of non-thermal plasma-based filters are multifaceted. Not only are MERV 8 filters more energy efficient, but they are also 66% less expensive to replace than MERV 13 filters. Maintenance costs are reduced because evaporator coils will need less or possibly no cleaning of biological slime that commonly adheres to dark, moist HVAC interiors. Clean coils result in better thermal transfer and HVAC energy efficiency. Maintenance requires vacuuming the filter every six months.

Instituting mitigations for future catastrophic events is a marketing tool many real estate managers are investing in today. Whether the intent is to mitigate the next pathogen or just capture everyday allergens, mold, mildew and PM2.5 for general occupant health, incorporating and marketing IAQ practices and equipment upgrades can be a smart business move.

ASHRAE Standards Become the Norm

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) published its new Standard 241 “Control of Infectious Aerosols” in 2023 to reduce the risk of infectious aerosol transmission in buildings. ASHRAE 241 research studies found that increased outdoor air ventilation combined with new innovative HVAC system air filtration technologies can significantly reduce and mitigate viruses such as SARS CoV-2, which causes COVID-19.

Consequently, cities across the nation are now modifying codes to include Standard 241 recommendations with the goal of keeping commercial and residential building occupants healthier during pandemics and year-round.

Wildfire Smoke + New HVAC Codes = Advanced Filtration Needs