Facility Managers Improve IAQ by Combining UV-C and MERV 8

Facility Managers Improve IAQ by
Combining UV-C and MERV 8 Technologies

Since the COVID-19 pandemic began, many of the recommended HVAC-oriented infection mitigation strategies have revolved around increased ventilation, increased filter efficiency, and ultraviolet energy—often in a layered approach.

The underlying infection control strategy herein is to dilute (ventilation) or remove (filter, UVGI) pathogen concentrations.

But what happens when infection mitigation objectives inadvertently inhibit ventilation levels? In other words, what happens when the HVAC equipment onsite is not mechanically capable of delivering the recommended air filtration performance?

ASHRAE guidance–and by extension–the Centers for Disease Control and Prevention (CDC), recommend facility managers upgrade HVAC filters to the equivalent of a MERV 13. [1]

HVAC manufacturers and facility engineers are quick to caution that not all AHU systems–particularly the large number of aging systems–can handle the high airflow restrictions and static pressure commonly associated with high-efficiency MERV 13.

Adding a high-efficiency HVAC filter can reduce airflow—essentially starving the machine of air like a dirty or fouled air filter. Limiting airflow inhibits heat transfer, forcing HVAC engineers to increase the fan speed or lower chilled water temperatures to compensate, which raises energy consumption.

Fortunately, there is an easy-to-implement alternative for the millions of HVAC systems that were never intended to perform with MERV 13+ filters.

Through a layered approach, facility engineers can combine medium-efficiency filters (MERV 8) with ultraviolet germicidal irradiation (UVGI or shortwave energy in the ultraviolet C spectrum) to meet or exceed MERV 13 level efficiency rates without sacrificing airflow or compromising cooling capacity.

In other words, thousands of building managers can comply with federal indoor air quality recommendations without limiting airflow and obstructing HVAC system operation.

Third-party, independent testing has shown that combining UV C together with a MERV 8 prefilter exceeded a 99% average single-pass reduction of the aerosolized SARS CoV 2 virus. This exceeds the removal rate of the MERV 13 filter that health agencies and industry advocates recommend.

Moreover, the low-pressure drop associated with the MERV 8 air filter significantly reduces fan horsepower (e.g., saves HVAC energy consumption) and maintenance costs.

[1] ASHRAE. ASHRAE Technical Resources; Filtration and Disinfection FAQ. Retrieved from https://www.ashrae.org/technical-resources/filtration-and-disinfection-faq