Keys to creating optimal post-COVID ventilation

NATIONAL REPORT—As the COVID-19 pandemic continues, air quality has become as important as ever for owners and operators. They need to make sure that the air is free of viruses and pathogens in order to keep their staff and guests safe.

“COVID-19 has shined a spotlight on indoor air quality and ventilation. It seems clear that business owners, employees and customers with chronic respiratory illnesses like asthma, COPD and emphysema all benefit from improved indoor air quality and whole building ventilation,” said Mona Kelley,  managing member & regulatory affairs specialist with Lake Wales, FL-based Natural Air E-Controls LLC. “This is true even outside of the flu and respiratory illness season. Short- and long-term exposure to any poor air quality can not only cause exacerbations of chronic respiratory illness and reduce lung function, but these same factors have been associated with increased severity of COVID-19 pneumonia and increased risk of contracting airborne illnesses in people both with and without chronic respiratory illnesses.”

Kelley, whose company designs and builds HVAC control systems that enable the building’s HVAC equipment to provide fresh air and remove pollutants by taking in outdoor air in amounts needed to improve indoor air quality, while saving on heating and cooling bills, noted that experts from the commercial building industry, US EPA Energy Star program and American Society of Heating, Refrigeration, Air-conditioning Engineers (ASHRAE) met in May to discuss how to best operate HVAC and related systems, and to offer recommendations on building HVAC operations amid COVID-19.

ASHRAE offered some essential tips to prepare buildings for occupancy re-entry, including flushing the air and water systems; assessing the air filtration systems; ensuring that the HVAC systems undergo maintenance, cleaning and are operating normally; and installing a Smart whole-building ventilation controller system.

“In April, the director of the CDC stated that fresh air ventilation was key to reducing airborne spread of COVID-19 in businesses,” Kelley said. “In June, ASHRAE recommended dilutional ventilation for all HVAC systems to reduce accumulated coronavirus and maintain indoor air quality.”

Besides viruses and other pathogens, there are other agents that can affect air quality. “These range from employee and customer personal care products such as cosmetics, perfume and hair care products, to sources of fossil fuel heat,” noted Kelley. “In addition, many cleaning agents, radon, humidity and mold can add to respiratory burdens. Experts recommend using simple measures to decrease exposure to air pollutants such as cleaning; not allowing smoking; using dehumidifiers in high-humidity areas; installing carbon monoxide and radon monitors; and ensuring adequate ventilation through air exchange options.”

The experts at the May meeting pointed out that an HVAC can help prevent the spread of COVID-19 by incorporating evolving best practices that focus on Smart whole-building ventilation in order to dilute airborne viruses and filtration to remove dust and airborne particulates. This can be accomplished by:

• Increasing whole-building ventilation using Smart ventilations controllers that compare indoor and outdoor air quality, and control outdoor air intake to prevent mold growth while maintaining minimum outside air flow to reduce the risk of airborne illness transmission.

• Improving filtration to MERV-13 or the highest efficiency level feasible, and ensuring that filters are sealed properly to prevent bypass.

• Using Smart whole-building ventilations controllers to provide outside air for several hours both before and after occupancy each day.

Also, consider adding UV sanitizers to the HVAC system as a secondary method to the fundamental measures listed above.

“MERV (Minimum Efficiency Reporting Value) is a measurement scale designed by ASHRAE to measure the effectiveness of HVAC filters to remove particles from air passing through the filter,” said Kelley. “MERV-13 is the minimum filter rating found to be effective at reducing airborne spread of COVID-19,” and added, “It should be noted that MERV-15 is more effective at reducing airborne illness.”

Kelley agreed that UV sanitizers should only be used secondary to more stringent air quality filtration methods.

“UV sanitizers do little to reduce viruses and bacteria and do nothing to reduce pollutants from ventilation systems,” she said. “Most UV sanitizers produce less than 30W of power, but 40-50W is the minimum UV power required to sanitize the HVAC coil and air pass through the HVAC system. Moreover, UV light needs to shine on both sides of the HVAC coil. Some UV lights use UV-activated metal reflectors that add ozone to the airstream. These UV lights also require 50W to activate the ozone producing metal. Ozone helps sanitize the HVAC coil and the air passing through the HVAC system.”

The experts also analyzed the energy-use impact of three measures to reduce virus transmission risk and recommended extending the hours an HVAC is in use to provide additional outside air for several hours both before and after occupancy each day; upgrading to MERV-13 from MERV-8 filters; and letting in an additional 50% outside air above minimum standards.”

“Experts found that these changes would result in a 3 to 5% increase in building energy usage, depending on the climate and region,” said Kelley. “Smart whole-building ventilation controllers, however, yield up to 30% energy savings. Therefore, implementing new post-COVID-19 ventilation standards with a Smart whole-building ventilation controller will still yield a net energy savings.” HB