Testing protocol mimics real-life operation of air cleaners in commercial buildings
June 10, 2020 (updated March 29, 2021) – enVerid Systems is pleased to announce new third-party test results showing that its HVAC Load Reduction (HLR) modules have a single-pass efficiency of 75.6% for the removal of viruses from air that passes through its modules. This is in addition to HLR air scrubber technologies’ ability to safely remove gaseous contaminants such as CO2, ozone, formaldehyde, and VOCs from indoor air without producing any byproducts.
The COVID-19 pandemic has led to questions about possible airborne transmission of viruses such as SARS-CoV-2 in buildings. While scientists continue to investigate the possibility that SARS-CoV-2 can be transmitted through HVAC systems, ASHRAE, the leading global standards body for the built environment, has stated that the “Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled.” (Note: On March 29, 2021, ASHRAE revised its statement to say “Airborne transmission of SARS-CoV-2 is significant and should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.”)
The HLR module’s virus removal efficiency was tested in similar conditions to the standard HLR module operation and air flow. Additionally, the benign virus used as a surrogate for the COVID-19 virus was aerosolized to simulate the potential flow of virus aerosols in buildings. Carefully calibrating test conditions to resemble the real-life operation of air cleaners in buildings, and using samples similar to the air present in an office setting, are necessary to demonstrate the effectiveness of any air cleaner at removing airborne viruses such as COVID-19 in a commercial environment.
enVerid’s test results are being released on the heels of, and in contrast with, announcements from several manufacturers of ionizer-based air cleaners. These announcements highlight very high rates of virus removal – over 99% – but not of airborne viruses. Rather, these test results appear to be confined to application on static viruses on surfaces over extended periods of time (e.g., 30 mins) without introducing continuous sources of new viruses. Such results, even if they were confirmed and published by a reputable third party, have no bearing on continuous removal of airborne microbes, which is the issue at hand. Results from surface tests do not address the potential airborne transmission of viruses.
enVerid recommends that all manufacturers claiming to support indoor air quality should release the details of their testing methodologies and the full test results to ensure consistent evaluation and clear comparison.
HLR Module Testing Protocol & Results
The virus tested by LMS Technologies, an independent air media and filter testing company based in Bloomington, Minnesota, is called MS-2- bacteriophage and was used as a surrogate for SARS-CoV-2, the virus behind COVID-19. The MS-2- bacteriophage virus is not toxic to humans.
LMS Technologies’ testing protocol was similar to the single-pass efficiency testing protocol used for testing the removal of gases such as CO2, ozone, formaldehyde, and VOCs under ASHRAE 145.2, the Laboratory Test Method for Assessing the Performance of Gas-Phase Air-Cleaning Systems. One HLR cartridge was challenged with air containing a known number of viruses that were aerosolized (virus particles packed inside small liquid drops that are airborne) to mimic the way viruses might be present in building air. The aerosols’ size ranged from 16nm-604nm. The number of live viruses were counted before and after the air passed through the cartridge to determine the cartridge’s single pass efficiency. The test was performed three times with results ranging from 74.3% to 76.8%, highlighting the consistency of the cartridge efficiency.
It is important to note, because the size of the SARS-CoV-2 virus is more than four times larger than the MS-2-bacteriophage virus, it is likely that the HLR module’s single-pass efficiency for SARS-CoV-2 is higher than 75.6%.
Implications for COVID-19
“The third-party tests conducted by LMS Technologies confirm that enVerid’s HLR modules can help address the potential airborne transmission of viruses,” said Christian Weeks, CEO of enVerid Systems. “In light of the growing interest in indoor air quality, we are very pleased to confirm that our technology can help in the fight against COVID-19.”
HLR modules are only designed to clean a portion of the total air in circulation at any point in time. Therefore, a complete strategy to address the possible airborne transmission of viruses should also include central air handling filters rated MERV13 or higher. Increasing ventilation may also make sense in certain cases, especially for existing buildings that cannot upgrade their filtration.
enVerid has researched the relative efficacy and cost of various ventilation and filtration approaches to reduce the risk of airborne transmission of SARS-CoV-2 in commercial buildings. A cost/benefit risk model is available for HVAC engineers and building owners to design cost-effective HVAC systems that reduce the potential airborne transmission of SARS-CoV-2 in commercial buildings.
More information about the cost/benefit risk model, the test results, and how enVerid’s HLR technology makes buildings healthier through improved indoor air quality is available on and by emailing .
HLR Overview
The enVerid HVAC Load Reduction® (HLR®) module is an intelligent air scrubber that removes all indoor air contaminants, including carbon dioxide (CO2), aldehydes and volatile organic compounds (VOCs). HLR technology represents a vital addition to conventional HVAC systems to reduce the heating and cooling load of outside air. Where traditional commercial HVAC designs rely on massive volumes of outside air to maintain indoor air quality, often resulting in a 30 to 50 percent waste in HVAC energy consumption, enVerid products significantly lower upfront system costs and reduce annual energy consumption by up to 30 percent while improving indoor air quality. In 2017, the U.S. Department of Energy ranked enVerid’s HLR product as one of the top three energy-saving technologies for commercial buildings, and in 2019 HLR was named the ASHRAE AHR Expo’s Product of the Year.
More information about the cost/benefit risk model, the test results, and how enVerid’s HLR technology makes buildings healthier through improved indoor air quality is available on and by emailing .