Ongoing health crisis triggered by pandemic has brought the debate on IAQ from HVAC industry circles to the attention of public and masses. For that reason, HVAC strategies may include protection through increased ventilation, improved filtration, and indoor air-cleaning to contain pollutants and Covid risks. Indoor spaces can be more risky than the outdoors, since it is rather not possible to keep people apart and there is less ventilation indoors. One of the simplest ways – to prevent the indoor spread of any virus – is to increase the volume of outside air that comes into the building. It’s better to take precautions through HVAC improvements to reduce the potential for airborne transmission.

Indoor spaces are more risky than outdoor spaces where it might be harder to keep people apart and there’s less ventilation. – CDC

Ventilation and Air filtration: ASHRAE and EPA position

Increasing the amount of outdoor air coming indoors is a constructive way to lowering the concentrations of indoor air pollutants including any viruses that may be in the air – is to increase the amount of outdoor air coming indoors. Ensuring proper ventilation with outside air can help reduce the concentration of airborne contaminants, including viruses indoors. National Air Filtration Association says, while some higher-efficiency filters can remove particles that contain Covid virus, low-efficiency filters—less than MERV 8—are unlikely to make a difference. Filtration and irradiation are suggested as common methods of purifying contaminated air.

EPA’s position is that improvements in ventilation and filtration cannot eliminate the risk of SARS-CoV-2 transmission on their own. It suggests increasing ventilation and air filtration along with implementing other precautions like social distancing, wearing cloth face coverings or masks, surface cleaning and disinfecting, and hand-washing. The Centers for Disease Control and prevention (CDC), Environmental Protection Agency (EPA), and Occupational Safety and Health Administration (OSHA) – all recommend regular cleaning and disinfecting commonly touched surfaces in public indoor spaces, including workplaces.

ASHRAE’s position is that ventilation and filtration provided by HVAC systems can reduce airborne concentration of covid virus and thus the risk of transmission through the air. Ashrae recommends that building operators use a filter with a Minimum Efficiency Reporting Value (MERV) of 13, but suggests that a MERV 14 filter is preferred.

MERV system for filters

MERV system on the measurement scale (1-16), created by ASHRAE, is designed to report the effectiveness of air filters.  Smaller particles are captured through filters with a higher MERV rating. A usual business, including a restaurant, might have a MERV-8 filtration system, which captures larger particles.  “Those filters don’t do anything really for COVID,” said Patrick O’Neill, North American president at mCloud Technologies, that works with retailers and restaurants to ensure their indoor air quality meets or exceeds commercial building standards established by Ashrae. As ventilation becomes another top-of-mind COVID safety protocol, restaurants need to examine their HVAC systems.

Patrick O’Neill

Patrick O’Neill, North American president at mCloud Technologies said, “MERV-13 looks like it’s covered with a cotton cloth. It’s like an accordion inside so you’ve got a lot of surface area that the air has to flow through. That’s really the threshold that most people consider effective for removing a meaningful amount of virus load from the air.”

HVAC System Market to grow at 6.5% CAGR

The opportunities in developing markets continue to grow with innovations driving the HVAC Systems market. Safety device protects HVAC systems from any electrical hazards. The global HVAC system market size is expected to grow from USD 202 billion in 2020 to USD 277 billion by 2025, at a CAGR of 6.5%. The market growth is fueled by growing demand for energy-efficient solutions, rising government incentives, and an increasing trend of smart homes. Smarter technology has enabled customers to control processes such as ventilation through smartphone apps., while other mobile technologies enable preventative maintenance and service programs.

WHO’s guidance on ventilation and AC systems

For safety, World Health Organisation (WHO) along with World Meteorological Organization Joint Office for Climate and Health and U.S. National Oceanic and Atmospheric Administration, has recommended several steps to improve indoor ventilation and air filtration to improve air.

WHO’s COVID-19 Dashboard

WHO’s 194 Member States are expected to adopt a resolution to strengthen preparedness for health emergencies, at the resumed 73rd World Health Assembly. It calls on the global health community to ensure that all countries are better equipped to detect and respond to cases of COVID-19 and other infectious diseases.  Globally, as of November 11, 2020, there have been 5,12,51,715 confirmed cases of COVID-19, including 12,70,930 deaths, reported to WHO, since the start of the pandemic.

WHO’s guidance on ventilation and air-conditioning systems in the context of COVID-19. Steps can be undertaken to improve ventilation and air conditioning in public spaces and buildings. Operating commercial office buildings, under epidemic conditions, require a holistic framework during the crisis and the restoration to a new normal after the public health emergency has ended.

  • Consider using natural ventilation, opening windows if possible and safe to do so.
  • For mechanical systems, increase the percentage of outdoor air, using economizer modes of HVAC operations and potentially as high as 100%.
  • Consider running the HVAC system at maximum outside airflow for 2 hours before and after spaces are occupied.
  • Increase total airflow supply to occupied spaces, if possible.
  • Disable demand-control ventilation controls that reduce air supply based on temperature or occupancy.
  • Improve central air filtration.

Comprehensively, to properly manage or upgrade HVAC systems, businesses, employers and building managers will need the services of facilities staff and vendors. Additional precautions are warranted in facilities that remained unoccupied during stay-at-home orders. Standing water in plumbing and ventilation systems is vulnerable to legionella incursion, resulting in Legionnaire’s Disease infections.

Cloth face coverings and surgical masks can impede flow of aerosolized particles from an infected individual but are not recognized as PPE that filter out particles. A wide range of options are available to choose from – to help protect citizens.  EPA has now approved more than 500 surface disinfectant products for use against coronavirus that causes COVID-19. This is important for ensuring businesses, families, schools, and other organizations have as many tools as possible to disinfect surfaces and protect themselves and families against the novel coronavirus.

Restaurants: Cleaning indoor air

Since the pandemic hit in March, restaurants have been focusing on curbing spread of the coronavirus by expanding sanitation of high-touch surfaces, adding barriers between tables, creating more outdoor seating, wearing masks and implementing distancing protocols. But now, the industry faces one more safety challenge: cleaning indoor air. “We’re turning the air over several times per hour in the room,” said Marc Zimmerman, chef-owner of GOZU in San Francisco. Prior to reopening his fine-dining concept in October, he installed a UV irradiation sanitizing system in the dining room. The hospital-grade system safely sanitizes ceiling air in the intimate 45 seat restaurant. Several restaurant owners now have to look at how to ‘scrub’ air by using pathogen-killing UV-C light or upgrading ventilation systems. The move comes – as health authorities learn more about how COVID-19 is spread.

Major cities globally, have listed ventilation guidelines for restaurants with indoor dining. Both recommend restaurants install higher MERV-rated filters. Allowing dine-in with capacity restrictions in late September, restaurants should use MERV-13 or higher filters or use an industry equivalent.

UV-C light is germicidal. With some HVAC systems unable to accept MERV-13 or higher filters, some restaurants are using UV-C devices in ducts. That can be the “preferred approach for forced air HVAC systems, which are the most common types found in restaurants.” Ultimately, when it comes to ventilation systems, it needs to be certain to treat the restaurant the same way you’ve been told to treat yourself: Follow safety protocols.

Air sanitizing vs. ventilation

Officials with the CDC and Prevention say COVID-19 is primarily spread through respiratory droplets; when near another person. In late September, when New York City allowed restaurants to reopen for indoor dining, the city told restaurants to examine their ventilation systems — even recommending a minimum standard for filters. “Such environments and activities may contribute to the buildup of virus-carrying particles”, CDC stated in an October 5 memo titled, “How COVID is Spread.”

Zimmerman said, “As a chef, we’re definitely not pandemic experts.” He and his partner settled on UV Guardian, a product that uses UV-C light to eliminate both airborne and contact-surface pathogens. UV-C has the most energy of the three types of UV light, and is known to destroy other types of coronaviruses, according to the National Academy
of Sciences.

Experts say UV light is one way to sanitize indoor air, but the main way to curb spread of the novel coronavirus is through proper ventilation. That’s why the CDC, state and local health officials have consistently recommended outdoor dining over indoor dining during the pandemic. There is new guidance for restaurants when it comes to indoor air circulation. CDC says COVID-19 can sometimes be spread by airborne transmissions when small droplets and particles linger in the air for minutes to hours. The restaurants, should have, certified experts check ventilation systems to ensure they function properly. The CDC also recommends increasing the “circulation of outdoor air as much as possible” by opening windows.

Dr. Mark Ereth

Dr. Mark Ereth, chief medical officer at SecureAire LLC says, “This is an exceedingly complex problem with no simple solutions. I think that’s the most important thing that people have to understand.”

While it’s not energy efficient, some building and health experts also recommend businesses open dampers to flood indoor spaces with fresh outdoor air as a way to dilute indoor contaminants.

Indoor thermal comfort

In the longer term, consideration of infectious disease transmission needs to be embedded into building ventilation regulations and associated statutory guidance – in the same way – that energy, comfort and air quality have been incorporated. Scientific Advisory Group for Emergencies (SAGE) experts state in a paper released, “Ventilation is an important factor in mitigating against the risk of far-field (>2m) aerosol transmission … Activities that may generate high levels of aerosol (singing, loud speech, aerobic activity) are likely to pose the greatest risk; in some spaces even enhanced ventilation may not fully mitigate this risk.”

HVAC system should be operated and maintained consistent with its instructions, to provide acceptable indoor thermal conditions, which is normally in the range of 68-780F (20-250C) and 40-60% relative humidity, curtailing the spread of COVID.  Ereth and O’Neill say, pathogens live longer in very dry or very wet environments, so keeping relative humidity in this range is good for restaurants.

Dr. Kevin

 Dr. Kevin Van Den Wymelenberg, director of Institute for Health in the Built Environment states, “We’ve designed buildings for 100-year floods.”Now we have to learn to design for the 100-year flu.” While the scale of the current pandemic is new, the need for architects to prioritize human health is not, says Dr. Kevin. The common sign among all these changes is that they will happen only, if public continues to prioritize indoor health after the acute crisis of pandemic has passed.

Professionals who operate school, office, and commercial buildings should consult guidance by ASHRAE and other professional organizations for information on ventilation and air filtration to help reduce risks from the virus causing COVID-19. ASHRAE recommends to follow guidance of CDC, which includes minimizing contact as much as possible. Devices like ultraviolet germicidal irradiation (UVGI) are helpful eliminating virus. Using EPA-registered cleaning and disinfecting products according to their label instructions is the best way to ensure that any indoor air pollution risks are reduced.

Further, for HVAC contractors, 2020 has been a year of constant changes. Even now, with the future of the pandemic uncertain, contractors need to consistently revisit company policies to ensure they are keeping technicians and customers safe.

Concluding remarks

Ventilation is essential to cleaning air and disinfecting for improved indoor air quality. Homes are generally the safest environment we have.  Regardless of the kind of home we live in, we are being optimistic to stay there as much as possible to mitigate the spread of COVID disease. Public health officials agree that one of the simplest ways to prevent the indoor spread of any contagious virus is to increase the volume of outside air that comes into our buildings.

Ventilation and air conditioning companies are developing new solutions and working in partnership with control suppliers, with those who specify and regulators specially – to resolve.  Nevertheless, it is clear the trend will continue even when the Covid-19 emergency is finally tamed. This will widen the concept of sustainability in construction, aiming with objectives which includes health, wellness and workers’ productivity.

So, before long but soon, ventilation options, regulatory requirements, building end-user requests, and tools to mitigate the virus associated risks, will make IAQ an essential aspect of specification for approval and creating standards. Truly, environmental goodness and health prospect for public may necessitate increasing innovations. Realizing, that the whole is more than some of its parts; in the long run, creating holistic environments is imperative. It will shore up human beings immune function making them apparently impervious to external pathogens causing infection.

Summing up: carrying caring concerns, the 2020 global pandemic has accelerated interest and awareness of the risk-free indoor air space in built environment dealing with such ongoing intricacies in future.


By Gopal Krishna Anand, Editor, Cooling India