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For decadesÌýwe must deal with a significantly decreasing air quality caused byÌýindustrialization, wildfires, higher temperatures leading to an increase inÌýharmful air pollutants.ÌýFor thisÌýreason, there is a strong trend toward higher performance filter systems. WhenÌýCOVID-19 surfaced, it accelerated this trend and gave global visibility to theÌýimportance of improved indoor air quality in both residential and commercialÌýapplications.

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MERV filter ratingsÌý

In NorthÌýAmerica, filters are rated by MERV – Minimum Efficiency Reporting ValueÌý– withÌýhigher numbers indicating better performance in removingÌýparticulates/contaminants (an analogous system exists in Europe under ISOÌýstandards). A typical residential filter resides in the MERV 8 performanceÌýrange, while most hospitals utilize filters in the MERV 14 or higher range –Ìýoftentimes, using multiple filters in sequence to achieve the high level ofÌýfiltration required for hospital applications.

The tableÌýbelow demonstrates how higher rated MERV filters are able to filter moreÌýcontaminants out of the air, with MERV 13 to MERV 20 filtering all the way downÌýto the level of a virus carrier (debris that ranges from 0.3 microns to 1.0Ìýmicron in diameter).

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Increasing filtration requirementsÌý

As theÌýpandemic progressed, we saw a further focus on higher efficiency media andÌýincreased ventilation across all applications. The CDC and ASHRAE provideÌýgeneral guidance for the use of higher-efficiency filter media where possible –Ìýrecommending at least MERV 13 to combat SARS-CoV-2, the virus that causesÌýCOVID-19.

With theÌýonset of COVID-19, these higher rated filters have become an area of focus forÌýmany building and HVAC system designers who are looking for solutions that couldÌýpotentially help slow or stop the spread of the virus between rooms. WhileÌýhistorically, these types of filters have been required only in hospitals, weÌýare now seeing emphasis on high filtration media for commercial buildings,Ìýhomes, and schools as a potential stop gap to help protect building occupants.ÌýFor residential settings, the California Energy Commission (CEC) recentlyÌýmandated that MERV 13 filter media be used in new construction, per Title 24ÌýStandards. Last year, the state of New York ordered shopping mall owners toÌýupgrade to MERV 13 filters as a condition of reopening in the summer.

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HEPA filters

TheÌýprevalence of HEPA (High-Efficiency Particulate Air) media, which is media withÌýhigher particulate efficiency than the MERV designation, is also increasingÌýrapidly in medical applications, commercial settings, and even schools. HEPAÌýfilters are designed to capture 99.97% of particles that are 0.3 microns orÌýlarger. If we see a significant shift toward HEPA media, it is worth notingÌýthat some HVAC systems will need to be upgraded to augment air flow, in orderÌýto balance increased system pressure requirements against more efficientÌýfiltration media.

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Associated challengesÌý

With thisÌýincreased emphasis on filtration comes higher performance requirements andÌýgreater demands on filter media, including more frequent filter changes. It isÌýalso likely that many HVAC system designers will need to begin considering theÌýimpact of high performing filtration media on HVAC system airflow and energyÌýrequirements to ensure that system performance does not suffer as a result ofÌýimproved filtration.

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Filtration media solutionsÌý

JohnsÌýManville provides a wide range of product coverings for the production ofÌýpocket and pleated filters for HVAC systems in hospitals, the food and beverageÌýindustry, the pharmaceutical industry and various industrial applications. OurÌýHVAC glass microfiber media effectively filters fine dust, bacteria, paintÌýpigments and tobacco smoke by combining low pressure drop with a high dustÌýholding capacity.Ìý

For moreÌýinformation on JM’s air filtration media, visit the HVAC filtration page of ourÌýEngineered Products division.