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Air Quality Improvement Strategies to Protect Your District While Reopening During COVID-19

COVID-19 has made this back-to-school season more complicated than ever. If you are preparing for your school to reopen, here are some things to consider:

  • What can you do with your existing building automation system (BAS)?

  • What can you do in addition to building automation improvements?

  • What facility updates are being recommended?

We recently hosted a 60-minute webinar that discusses best practices and control strategies to help improve indoor air quality and slow the transmission of viruses through enhancements to your HVAC and BAS system.

No time to watch? Keep reading below for a short summary and overview of how Plug Smart can help.


How to Use Your Building Automation System to Meet COVID-19 Guidelines [Webinar]

Request the webinar, here!


The World Health Organization (WHO) has often repeated that Coronavirus is spread primarily by large respiratory droplets that are expelled through coughing and sneezing. Therefore, airborne transmission may be a greater threat indoors, and changing the operation of your HVAC system can reduce the exposure.

While wearing masks and sanitizing surfaces are still necessary, there are additional steps that you can take to improve the air quality and ventilation in your school.

Evaluate your BAS

Before you plan to implement any changes, review your current system(s). Is your system a legacy pneumatic system or a modern, district-wide digital system or somewhere in-between? To efficiently manage and implement changes, ensure your BAS has remote access. Your district IT provider will be able to help you establish remote connectivity for your system so you can easily access your building’s data whether you are on-site or remotely connected.

Once the remote access is confirmed:

  1. Execute a systemwide backup

  2. Perform a preventative maintenance inspection

  3. Prepare a deficiency log and correct any critical issues

After confirmation that your BAS is ready for changes, review your air distribution conditions.

Update Your Controls

Your air distribution can be impacted by windows and fans but is most controlled by your HVAC system. When taking steps to improve air quality, bringing in fresh air is critical. Ventilation will help remove or dilute any airborne pollutants. We recommend following the ASHRAE 62.1 Guidelines for occupancy and square footage to increase your outside air as much as possible. Additionally, here are other items to add to your “controls checklist”:

  1. Check outside air and relief/exhaust air dampers and controls for proper operation

  2. Schedule daily air purge/flush pre and post occupancy

  3. Increase outdoor air to maximum allowable without comprising indoor comfort: Check air quality sensors and pollution data

  4. Monitor your control trends: Watch for temperature and humidity maximums and minimums

  5. Keep positive building pressure: Negative pressures introduce future issues like mold

  6. Increase filtration

  7. In VAVs, maximize the total supply air flow

Please note: increasing your use of outdoor air will alter your humidity and indoor air temperature. You should inform your stakeholders that your energy use and associated costs will most likely increase. However, if the relative humidity stays between 40 and 60%, it decreases the infectivity of viruses in the air.

After determining what changes are appropriate, make small changes to the system at a time and monitor for a few days or through some varying weather conditions to make sure the system and building(s) are responding to the changes as expected.

Alternate Hardware Solutions

In addition to making the above updates to your controls setting and BAS, there are hardware options such as filters, UV lamps, and ionization, that you can include in your existing air systems to increase filtration efficiency and air disinfection during this pandemic.


The filtration approach seeks to increase outside air while treating the return air via mechanical filtration. The target level for filtration for schools is MERV (Minimum Efficiency Reporting Value) 13 or higher. The MERV rating reports the filter’s ability to capture larger particles and is on a scale from 1 to 16.

As the MERV rating number goes up, so does the pressure drop across the filters. As you consider updating your building’s filters, you must ensure the pressure drop is less than your fan’s capability. To do so, locate and verify the last Test & Balance (TAB) report to determine air flow and static pressure values.

Regardless of if you upgrade the filters or not, you should continue with your normal filter maintenance schedule. In controlled indoor environments, filters are typically changed multiple times a year. There are no specific COVID-19 restrictions on disposing of the filters, but when handling, gloves, eye protection, and a respirator (N95 or higher) should be worn.

Ultraviolet (UV) Energy

The entire UV spectrum is capable of inactivating microorganisms, but UV-C energy (wavelengths of 100-280nm) provide the most germicidal effect. For air quality purposes, the optimal wavelength is 265nm.

UV lamps are very effective at maintaining the cleanliness of HVAC coils, drain pans, and other wetted surfaces. However, the success of UV is all about intensity and exposure time. UV requires special PPE to prevent damage to the eyes and skin from overexposure and requires extra consideration/material on surrounding windows, gaskets, and filters.


Care and professional judgement should be taken to understand all of the choices for filtration and air disinfection. However, certified installation is a must for ionization. Ionization uses high voltage electrodes to create reactive ions in the air that react with airborne contaminants. When it is installed upstream of the cooling coils, it creates a plasma field. Not only does it clean the AHU, but billions of ions go out into the space to kill pathogens, mold spores, and viruses. When evaluating ionization products, look for solutions that do not produce ozone.

Checklist Before Fall Start

We have compiled a few of the main steps that you should consider and evaluate before you open your school. For the full checklist of recommended actions, please read the ASHRAE Guidelines for Schools and Universities.

Before Reopening:

  1. Check your systems’ health: Ensure all parts are in good condition

  2. Update your BAS: (i) Monitor trends; (ii) Up your outdoor air intake; (iii) Set to occupied mode for one week to flush the system prior to full occupancy

  3. Review filtration and air disinfection hardware: Replace or install necessary equipment

For more information or to schedule a consultation/facility audit, please email us at Plug Smart’s team of engineers has spent thousands of hours working on HVAC and BAS projects and are ready to get your school prepared for the fall semester – whatever that may look like!


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