Reacting to New Guidelines in IAQ During a Pandemic: How Building Operators Can Leverage Their Data to Maintain a Safe, Comfortable Space

Jim Boler

The pandemic has certainly put a new focus on the indoor environment. During its early stages, maintenance personnel at commercial buildings, hospitals, hotels, and schools were paying closer attention to cleaning processes, cleaning schedules, and cleaning chemicals with the goal of ensuring surfaces were as germ and virus free as possible. There were (and are) hand sanitizing stations nearly everywhere. However, as scientists learned more about how the COVID-19 spread, determining that exposure was more likely through the air as opposed to through surface contact, facility managers and building operators quickly pivoted (as is their forte’), making certain that their buildings met new ventilation criteria aimed at making the indoors safer for individuals and groups to interact.

The primary steps taken to minimize COVID-19 spread in the indoor environment are to:

1. Replace standard air filters in AHUs and RTUs with filters rated to at least MERV 13 or the highest rated filter the existing system will allow, and
2. Introduce more outside air into the building with the goal of keeping the air the fresh and virus free to the maximum extent possible.

While a good maintenance program and team can ensure filters are changed when needed, ensuring additional outside air is effectively handled by the building’s systems requires additional study and continuous review.

There is certainly consensus that reprogramming the Building Management System to increase the outdoor air damper setting from its minimum to 100% open to maximize outside air, guarantees a whole different set of problems for the building and its occupants. Simply, a well-designed AHU or RTU will not have the capacity to deal with the additional cooling load in the summer or the extra heating load in the winter that is the result of bringing in four to ten times the expected amount of outside air through the unit. For example, a 12.5 Ton, 6000 CFM RTU with 20% outside air at 90 deg F and return air at 75 deg F can produce a leaving air temperature of 55 deg F to cool the downstream zones (setting aside latent impacts for simplicity). If the outside air percentage is changed to 100% to respond to COVID concerns, that same unit can only produce 67 deg F leaving air, well above the 55 deg F needed to maintain comfortable zones. A more realistic scenario would add humidity and a latent load to outside air stream, further degrading the unit’s performance and introducing cool/damp air to the building, resulting in not only comfort complaints, but an ideal environment for mold growth as well.

Since maximizing outside air percentage may introduce comfort problems and increase energy spend, what’s a better solution? We suggest using Automated Fault Analytics and Automated Dynamic Control to mitigate COVID concerns while minimizing excess energy expenditure that increasing the amount of outside air can introduce.

Automated Fault Analytics: The benefit of applying automated fault analytics to building and systems data is that it gives insight into actual performance. For example, not only can analytics tell you if the outside air damper isn’t working (i.e stuck open, stuck closed, or stuck somewhere in between), automated analytics can also calculate the actual percentage of outside air at the minimum outside air damper position, the fully open outside damper position, and any damper position in between. Understanding the actual amount of outside air, in combination with filtered MERV-13 recirculated air leads to a more accurate determination of the number of air changes per hour (ACH) needed to purge a given space. Further, automated analytics can continuously and accurately calculate ACH and alert building operators when the air change rate drops below the targeted number, or purge times need to be extended because of lower outside air percentages/quantity.

Automated Dynamic Control (ADC): ADC is a powerful addition to the application of automated analytics to a building’s equipment and systems. Whereas automated analytics are limited to detecting and reporting an issue when it occurs, ADC can mimic conditions to test proper performance or correct a condition. For example, ADC can be used to: simulate and test cooling equipment prior to cooling season, outside air dampers prior to economizing season, and heating equipment prior to heating season. By applying ADC in this way, a building owner can identify and repair equipment that needs maintenance before it is needed to maintain a comfortable environment or cause excess energy spend.

In an IAQ application, Automated Dynamic Control is used to make adjustments to purge times based on calculated percent of outdoor air entering the space and the calculated number of air changes based on airflow and room volume. Client business rules are used to determine if the outside air percentage, or overall air flow (or both), needs to be adjusted in order to modify a purge cycle to meet the client’s goals. ADC can also be used to predict remaining life on MERV 13 filters based on pressure drop and/or cumulative air flow through the filters.

Facility managers and building operators are experts at jumping through hoops and reacting to the latest crisis. They are also very good at setting up processes to address and mitigate crises. While quickly reacting with new processes is laudable, these new processes typically mean more tasks added to already overworked managers and their teams. This latest COVID -19 crisis present leaders with the opportunity to incorporate smart technology such as automated fault analytics and automated dynamic control into their building operations, enabling them to ensure IAQ goals are met while eliminating the need for new manually intensive processes.