Key Takeaways

• Any solution needs to be compatible with your building’s existing HVAC systems and functions. Verify that the product you have in mind is designed for your space.
• If you increase ventilation by introducing more circulating air, be mindful of any drafts or breezes that result. These could increase the movement of air and contaminated particles from one person to another.
  
• Adding new equipment can increase your building’s energy use. Consider whether you need to update your HVAC system’s sequence of operations to accommodate the new equipment and not overtax your utilities.
• Properly maintaining new and existing equipment will help you the most out of your mitigation strategies.
• Mitigation strategies can impact system and equipment longevity, because your equipment may run more frequently.
  

Since the onset of the COVID-19 pandemic, we’ve gotten a lot of questions about how to improve existing HVAC systems to protect people’s health and safety. Given the number of options available, we can appreciate that building owners may be uncertain about what option to choose.

When we evaluate COVID-19 mitigation measures for a building, our goal is to pinpoint solutions that work for the building, integrate with existing systems, and are not burdensome for the owner. The following 5 questions highlight key decision points. The answers can help you choose the best solutions for your facility.

Is This Solution Right for This Building?

To get the expected benefits, any solution needs to be compatible with your building’s existing HVAC systems and functions. Different products are designed for different settings, and some will be a better fit for your building than others.

You’ll also want to scrutinize the product information. What claims are the manufacturers making? What data backs up their claims? The goal is to verify that the equipment will work as advertised in your building, with your HVAC system.

For example, an organization might be tempted to buy off-the-shelf air purifiers for every room in their school or office. As an engineer, I would be asking whether the product could keep up with the building’s existing systems and the activities within the space. Twenty children in a daycare served by a commercial HVAC system is very different than one person in their home or small private office served by a residential HVAC system.

Could This Solution Introduce a New Health Risk?

This point has to do with how much we don’t know about COVID-19. The scientific community still has many questions about the novel coronavirus. For example, how long does the virus live while airborne? What concentration of the virus will lead to infection?

Ventilation is an important COVID-19 mitigation strategy. However, be careful that ventilation doesn’t get confused with air circulation. Typical HVAC systems allocate a portion of their total airflow to fresh air (ventilation). If the plan is to increase ventilation by introducing more circulating air within the space, this could create unnecessary drafts and air currents, which could increase the movement of air from one person to another. While you might reduce the overall particulate concentration in the air, you could increase person-to-person transfer.

This article gives a good visual of air transfer in a normally-operating building. It shows how air transfer can contribute to the spread of disease and, by extension, why you don’t want to increase air transfer.

The bottom line is, if you increase ventilation, watch out for drafts or breezes that could result.

What’s the Impact on Utility Bills?

Adding new equipment can increase your building’s overall energy use in two ways. First, the product itself may use energy. Different products can use drastically different amounts of energy (e.g. ultraviolet germicidal irradiation [UVGI] vs. bipolar ionization). Less obvious is the fact that your system operation might need to change for the product to be effective, and those changes can increase energy usage.

For example, with both UVGI and needlepoint bipolar ionization, manufacturer’s recommendations state that HVAC fans should operate 24/7 for the highest effectiveness. Buildings that already have 24/7 operations, such as hospitals, wouldn’t see much energy impact. Buildings with standard hours, such as schools and offices, could see a significant increase in energy usage.

Depending on your building’s hours and functions, though, 24/7 operation may not be what your building needs. ASHRAE, for example, suggests pre- and post-occupancy flushes to dilute the concentration of pathogens in the air (see ASHRAE’s Building Readiness Guidelines).

If you’re exploring solutions like bipolar ionization or UVGI, it’s worth giving thought to the appropriate system operations for your building. That way, you can implement a sequence of operations that doesn’t overtax your utilities.

What Are the Maintenance Requirements?

To maximize the effectiveness of your mitigation strategies, proper maintenance is essential.

Any product will likely have specific maintenance requirements. For example, if you’re selecting filters with a higher MERV rating, you’ll want to review the life expectancy of the filters. Some need to be changed more often than others. If you install UVGI, you’ll need to change the UV lightbulbs as directed. If you install non-self-cleaning needlepoint bipolar ionization equipment, you’ll need to clean it regularly.

Adding new products can also affect your existing system’s maintenance requirements. For example, as noted above, some air cleaning products recommend you run your HVAC system 24/7. As a result, you might need to compress the maintenance schedule for tasks like lubricating fan bearings, replacing belts, or changing air filters.

Will This Solution Affect HVAC Equipment Life?

Mitigation strategies have implications for overall system and equipment longevity. Depending on the strategy, your HVAC systems will run more frequently. As a result, your HVAC equipment will reach the end of its useful life more quickly.

These Solutions Supplement Other Mitigation Efforts

We’ve been asked whether people can stop wearing face masks if the HVAC system has advanced filtration or other air cleaning devices. The answer is “no.”

Any new equipment or changes to system operations supplement existing mitigation efforts. They don’t replace practices recommended by the CDC such as frequent handwashing, wearing face masks, regular surface cleaning, and social distancing.

At the end of the day, the goal of all COVID-19 mitigation strategies is to protect people and stop the spread of disease. Whatever option you choose, we want you to be successful with it.