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HVAC Systems and Reopening Buildings During COVID-19

HVAC Systems and Reopening Buildings During COVID-19Navigating HVAC systems and reopening buildings during COVID-19 may seem like a daunting task for facility managers. There are certain things facility managers can look out for to make sure HVAC systems are up to date and working properly for safe reopening. Continue reading below to learn more.

Today, in this uncertain world where a small virus can wreak havoc in the lives and livelihoods of so many, it’s almost a foregone conclusion that facility management leaders and their teams must make absolutely sure that everything humanly possible is done to assure a clean, healthy environment for those who work and visit their buildings.

In this Facility Executive article, our focus will be on the operational procedures used to reopen a facility previously closed due to CV19 (COVID-19), also known as the novel Coronavirus. From a HVAC perspective, we’ll briefly discuss the teamwork necessary, some of the more notable aspects associated with the procedures, as well as a few additional points of consideration.HVAC

Human-to-Human Transmission
There are two schools of thought with regards to how SARS-CoV-2 is transmitted (SARS-CoV2 is the virus that causes COVID-19). The first theory, endorsed by WHO (World Health Organization) and CDC (Centers for Disease Control) is that the virus is passed person to person by way of droplets at relatively short distances. In other words, it is passed by contact.

The second concept, endorsed by other organizations and individual health care professionals, is that the virus can become airborne, so it can be acquired at greater distances than the 6-foot criteria endorsed by CDC. There is, in fact, circumstantial evidence that SARS-CoV-2 can go airborne. Cases exist where the virus was spread over a considerable distance inside a structure.

Since there’s evidence proving that transmission can occur by contact and by aerosol action, we’ll assume that both theories are correct. Frankly, this is why it’s necessary to take every conceivable precaution to assure IAQ (indoor air quality) not only when you reopen your facility, but from that point forward.

The bottom line is this, the most important commodity that you have, as a facility executive, is the people who use your building as well as those who visit there. ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) of Atlanta, GA, reminds us that, with respect to IAQ, “Buildings are for people, not for saving energy” (quote by Society Presidential Member, Bjarne Olesen, of Denmark). With this in mind, let’s move forward with our mission, to discover the right methodology to use when reopening a building that has sat for a period of time.

HVAC Resources And Assembly Of A Reopening Team
Before resuming the daily operation of your HVAC systems, take an inventory of your resources to determine exactly what you have under the hood. You may see there are a variety of upgrades you might want to perform, but unless you have the means already in place, you may not be able to achieve them.

In order to do this safely, and within your budget, it’s imperative to know whether your system will accommodate those changes. An example is the AHU (Air Handling Unit) in your existing HVAC system. If the blower motor is not of sufficient power, you may not be able to advance the efficiency of your AHU’s air filtration. Your AHU consists of one or more blowers (fans), dampers, heating coils, cooling coils, humidifiers, dehumidifiers, sensors, and the controls needed to condition and distribute air throughout the building.

According to Sarah E. Maston, PE, BCxP, QCxP, LEED AP, owner of Green Footprint Commissioning Inc., of Hudson, MA: “It’s important to examine the HVAC documents, including the blueprints and other drawings. The as-builts are especially helpful because the installation team created them based on what was installed, where it was installed, and how it was installed. The original specifications are important, but they reflect what was called for, not what was specifically done.”

Maston is currently Director-at-Large on the ASHRAE Board of Directors (2018-21). And, for 2020-21, she is Chair of the Planning Committee at ASHRAE, which focuses on Strategic Planning for the Society.

In addition to all the above, facility management teams need to look for the following:

  • Up-to-date documents related to the HVAC and plumbing systems
  • Equipment submittals
  • BAS (Building Automation System) Reports
  • Recent TAB (Testing, Adjusting, and Balancing) and/or Commissioning Reports

Start with your own building management team and assemble what ASHRAE calls a “Building Readiness Team.” Be sure to know the companies and, if possible, the project managers involved in the original installation. This includes those involved in on-going maintenance, such as:

  • Commissioning Provider
  • Test and Balance Company
  • Building Automation System Firm
  • Contractors
  • Architect and/or Engineer (AE)

“You don’t want to go after what you think is a positive step to later find out that it’s going to cause you other issues that weren’t really identified up front. You need to start by building a team so you can take advantage of their technical resources,” says Maston. “You also need a commissioning engineer, like myself; and it’s almost certain you have a controls contractor under contract, so definitely talk with them.”

Look for any and all information you have about how the building operates. This is important because one of the first things you’re going to do is try to increase the filtration in the building. You might also look at bringing some additional outside air into the structure to help purge the building through a makeup air solution that removes air inside the structure, replacing it with new. You need to know whether these things are feasible and these people should be able to tell you if they can or cannot do it.

Importance Of Air Flow, Filtration, And Humidity Control
The need for environmental control during this COVID-19 crisis cannot be stressed enough because air filtration, air flow, and humidity are all three key components used in minimizing risk. This is why shutting down an HVAC system during a crisis such as this is not a good idea.

Filtration is an obviously important element in assuring IAQ because if you’re able to capture the virus in the filtration system, then they’re not able to make someone sick inside the building.

In most commercial HVAC systems, the filters are measured in MERV (Minimum Efficiency Reporting Values). The MERV measurement ascends in quality from MERV 1 through MERV 20, which is the highest. The most common found in a commercial AHU is MERV 6 to MERV 8. ASHRAE recommends a higher efficiency rating, ideally MERV 13 or MERV 14.

“What we’ve found is that for a particular size virus particle, if your system has allowed you to go up to a MERV 13 or 14 filter, the efficiency is considerably better at that limit. And that’s kind of the trade off,” says Maston. “Some systems might not be able to handle [a more efficient filter] because it takes a lot more energy to push air through it.”

The use of HEPA (High Efficiency Particulate Air) filters is not usually an option either. There two good reasons for this: 1) the relatively high cost of HEPA filters, and 2) these filters pose considerably more resistance to air flow than MERV filters do.

If the AHU’s blower(s) motor is not sufficient to the task, an increase of static pressure will slow the flow of air, which is counterproductive to the task of catching virus’ in the filtration system. In this regard, air flow is likewise a key component in the IAQ effort and cannot be ignored.

Good air flow will also assist in humidity control. Maston says that if you can maintain a relative humidity of 40% to 60% inside your facility, this will decrease the virus’ ability to infect occupants. If your HVAC system already incorporates makeup air, this also will increase ventilation, thus creating an even more healthy environment.


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