Three HVAC Measures To Combat COVID-19

If you already have UV-C installed, consider these three strategies that have been shown to contain the spread of COVID-19.

By James Piper, PE


While UV-C technology, carefully specified and installed in institutional and commercial facilities, can help prevent the spread of the coronavirus, maintenance and engineering managers can also take other measures to combat the spread of COVID-19.

1. HEPA filtration. Highly efficient particulate filters (HEPA) can remove more than 99.9 percent of particles 0.3 microns or more in diameter. These particles include pollen, dust, some bacteria, and some viruses. The coronavirus is about 0.1 micrometers in diameter, but since the virus typically adheres to exhaled water droplets that are 5 micrometers or larger, they can be easily captured by a HEPA filter. Tests have shown an efficiency rating for catching the coronavirus at 99.9 percent.

The high cost and increased energy demands of fans associated with the use of HEPA filters have limited their use to specific applications such as certain medical facilities and manufacturing clean rooms.

An alternative system with a relatively low initial and operating cost is a portable HEPA unit. These systems include a fan and managers can specify them for air purification in high risk areas or areas requiring additional protection. Different power units are available depending on the size of the application.

2. Ventilation rates of the outside air. Over the past few decades, HVAC systems have been designed to operate with a minimum of outside air. Increased amounts of outside air dilute indoor air pollutants, including COVID-19, but that benefit comes at a price. Higher outside air ventilation rates increase heating and air conditioning costs because the system must increase or decrease the temperature of the outside air to the temperature of the conditioned space.

Higher outdoor air rates alone couldn’t help much in the fight against the coronavirus as they don’t reduce the human-to-human spread indoors. However, higher ventilation rates combined with other best practices can contain the spread of the virus from one area of ​​a building to another area served by the same system.

3. Humidity. Studies of the effects of indoor humidity have shown that a relative humidity of 40-60 percent could help contain the spread of the coronavirus. Researchers have shown it stays in the air longer and therefore can travel further in dryer environments.

Not all HVAC systems can hold these levels, especially in winter. When managers try to maintain higher humidity levels, they need to ensure that technicians carefully monitor the operation of HVAC systems and air-conditioned rooms for condensation and mold growth.

James Piper, PE is a national consultant based in Bowie, Md. He has more than 35 years of experience in facility maintenance, engineering and management matters.

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