Co-Authored by Matt McMillen.
COVID-19 has made this year’s back-to-school season more complicated than ever. With school fully back in-swing, here are some technical and financial considerations as the last quarter of 2020 begins:
- Is the existing building automation system (BAS) capable of improving indoor air quality?
- Are more than ventilation-only air-quality measures being utilized?
- What facility best-practices and updated have been implemented?
- What measures can be financed by CARES Act funds?
Below is a short summary and overview of best practices and control strategies to help improve indoor air quality and slow the transmission of viruses through enhancements to HVAC and BAS systems for Ohio school districts.
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, the airborne transmission may be a greater threat indoors, and changing the operation of HVAC systems can reduce the exposure.
While wearing masks and sanitizing surfaces are still necessary, there are additional steps that should be taken to improve the air quality and ventilation in Ohio school facilities.Evaluate the Building Automation System
Before any plans for changes are implemented, the current system(s) should be reviewed regardless of whether the existing system is a legacy pneumatic system or a modern, district-wide digital system. To efficiently manage and implement changes, the BAS should have remote access. District IT staff and/or providers will be able to help establish remote connectivity for the system. This ensures maintenance personnel can access the building data whether they are on-site or remotely connected.
Once the remote access is confirmed, users should (i) execute a systemwide backup, (ii) perform a preventative maintenance inspection, and (iii) prepare a deficiency log and correct any critical issues. After confirmation that the BAS is ready for changes, review air distribution conditions.Update Building Controls
Air distribution can be impacted by windows and fans but is mostly controlled by the HVAC system. When taking steps to improve air quality, bringing in fresh air is critical. Ventilation will help remove or dilute any airborne pollutants. As outlined in ASHRAE 62.1 Guidelines, it is recommended to increase outside air as much as possible. Additionally, other items to add to this year’s “controls checklist” are provided below:
- Check outside air and relief/exhaust air dampers and controls for proper operation
- Schedule daily air purge/flush pre and post-occupancy
- Increase outdoor air to maximum allowable without comprising indoor comfort: Check air quality sensors and pollution data
- Monitor control trends: Watch for temperature and humidity maximums and minimums
- Keep positive building pressure: Negative pressures introduce future issues like mold
- Increase filtration
- In VAVs, maximize the total supply airflow
Please note: increasing the use of outdoor air will alter humidity and indoor air temperature; as a result, 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.
Also, make small changes-at-a-time to the system and monitor for a few days or through some varying weather conditions to ensure the system and building(s) are responding to the changes as expected.Supplementary Hardware Solutions
In addition to the above controls and BAS settings, there are hardware options such as filters, UV lamps, and ionization, that can be included in existing air systems to increase filtration efficiency and air disinfection. Filtration:
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 updates are implemented, the pressure drop must be less than the system’s fan capability. The Test & Balance (TAB) report can determine airflow and static pressure values.
Regardless of if filters are upgraded, existing maintenance schedules should be adhered to. In controlled indoor environments, filters are typically changed multiple times a year.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. Ionization
Care and professional judgment 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
A few of the main steps that should be considered and evaluated are provided below; for the full checklist of recommended actions, please read the ASHRAE Guidelines for Schools and Universities.
Maximize CARES Act/ESSER Funds
- Check systems’ health: Ensure all parts are in good condition
- Update BAS: (i) Monitor trends; (ii) Increase outdoor air intake; (iii) Set to occupied mode for one week to flush the system prior to full occupancy
- Review filtration and air disinfection hardware: Replace or install the necessary equipment
District allocations of the Elementary and Secondary School Emergency Relief Fund (ESSER Fund) from the 2020 CARES Act amounting to over $500 million statewide can be used for emergency facility repairs to improve the air quality and ventilation in Ohio schools as long as they meet program requirements (below). With three months remaining for eligible expenditures, the time to implement improvements is now.
The CARES Act provides that payments from the Fund may only be used to cover costs that:
Jarret Kelly is the Director of Engineering at Plug Smart. email@example.com | 614.230.7256.Matt McMillen is the Senior Building Systems Specialist at Plug Smart. firstname.lastname@example.org | 513.267.5547.
- Are necessary expenditures incurred due to the public health emergency with respect to the Coronavirus Disease 2019 (COVID–19);
- Were not accounted for in the budget most recently approved as of March 27, 2020 (the date of enactment of the CARES Act) for the State or government; and
- Were incurred during the period that begins on March 1, 2020, and ends on December 30, 2020