Providing a safe environment for your tenants and or employees is a major concern during the current pandemic. Office building employers, owners and managers, and operations specialists can take the following steps to create a safe and healthy workplace for workers and clients.
One of the most important things that you can do is to consider taking steps to improve ventilation in the building, in consultation with an HVAC professional, based on local environmental conditions (temperature/humidity) and ongoing community transmission in the area.
A licensed HVAC contractor can help you:
- Increase the percentage of outdoor air, (e.g., using economizer modes of HVAC operations) potentially as high as 100% (first verify compatibility with HVAC system capabilities for both temperature and humidity control as well as compatibility with outdoor/indoor air quality considerations).
- Increase total airflow supply to occupied spaces, if possible.
- Disable demand-control ventilation (DCV) controls that reduce air supply based on temperature or occupancy.
- Choose a mechanical air filter to improve air quality.
Mechanical Air Filters
Filters consist of media with porous structures of fibers or stretched membrane material to remove particles from airstreams.
Some filters have a static electrical charge applied to the media to increase particle removal. Since the efficiency of these filters often drops off over months of initial use, a MERV-A value, if available, will reflect the actual minimum efficiency better than a standard MERV value.
The fraction of particles removed from the air passing through a filter is termed “filter efficiency” and is provided by the Minimum Efficiency Reporting Value (MERV) under standard conditions.
MERV ranges from 1 to 16; higher MERV = higher efficiency
MERV ≥13 (or ISO equivalent) are efficient at capturing airborne viruses
MERV 14 (or ISO equivalent) filters are preferred
High-efficiency particulate air (HEPA) filters are more efficient than MERV 16 filters
Some filters have a static electrical charge applied to the media to increase particle removal. Since the efficiency of these filters often drops off over months of initial use, a MERV A value, if available, will reflect the actual minimum efficiency better than a standard MERV value.
Increased filter efficiency generally results in increased pressure drop through the filter. Ensure HVAC systems can handle filter upgrades without negative impacts to pressure differentials and/or airflow rates before changing filters.
Generally, particles with an aerodynamic diameter of around 0.3 μm are most penetrating; efficiency increases above and below this particle size.
The overall effectiveness of reducing particle concentrations depends on several factors:
Air flow rate through the filter
Size of the particles
Location of the filter in the HVAC system or room air cleaner
- By definition, true HEPA filters are at least 99.97% efficient at filtering 0.3 μm mass median diameter (MMD) particles in standard tests.
- Most penetrating particle sizes may be smaller than 0.3 μm, so the filtration efficiency of most penetrating particles can be slightly lower.
- HEPA filter efficiency is better than MERV 16.
- HEPA filters may not be an appropriate option for some into HVAC systems due to high-pressure drops and the likelihood that systems will need new filter racks to allow sufficient sealing to prevent filter bypass.
- To function properly, HEPA filters must be sealed properly in filter racks. Filters are often delicate and require careful handling to prevent damage and preserve performance.
- HEPA filters can be located in HVAC systems or in:
In-Room or Portable HEPA Machines
Ad Hoc Assemblies
Electronic Air Filters
- Include a wide variety of electrically-connected air-cleaning devices designed to remove particles from airstreams.
- Removal typically occurs by electrically charging the particles using corona wires or by generating ions (e.g., pin ionizers), and:
- Collecting particles on oppositely charged plates (precipitators, ESP),or
- Charged particles’ enhanced removal by a mechanical air filter, or
- Charged particles’ deposition on room surfaces.
- The fraction of particles removed from the air by an electronic filter is termed “removal efficiency.”
- The overall effectiveness of reducing particle concentrations depends on:
- Removal efficiency
- Air flow rate through the filter
- Size and number of particles
- Location of the filter in the HVAC system
- Maintenance and cleanliness of electronic filter components
- It is critical to wipe the wires in electrostatic precipitators as silicone buildup reduces efficiency.
- Always follow the manufacturer's instructions when using electronic air filters.
Ultraviolet Energy (UV-C)
- Ultraviolet energy inactivates viral, bacterial, and fungal organisms so they are unable to replicate and potentially cause disease.
- The entire UV spectrum is capable of inactivating microorganisms, but UV-C energy (wavelengths of 100 – 280 nm) provides the most germicidal effect, with 265 nm being the optimum wavelength.
- The majority of modern UVGI lamps create UV-C energy with an electrical discharge through a low-pressure gas (including mercury vapor) enclosed in a quartz tube, similar to fluorescent lamps.
- Roughly 95% of the energy produced by these lamps is radiated at a near-optimal wavelength of 253.7 nm.
- UV-C light-emitting diodes (LEDs) are emerging for use.
- Types of disinfection systems using UV-C energy:
- In-duct air disinfection
- Upper-air disinfection
- In-duct surface disinfection
- Portable room decontamination
- Requires special PPE to prevent damage to eyes and/or skin from overexposure.
Bipolar Ionization/Corona Discharge / Needlepoint Ionization and Other Ion or Reactive Oxygen Air Cleaners
- Air cleaners using reactive ions and/or reactive oxygen species (ROS) have become prevalent during the COVID-19 pandemic. New devices that are not mentioned elsewhere in this guidance likely fall into this category.
- Technologies utilize various methods to create reactive ions in the air that react with airborne contaminants, including viruses. The design of the systems can be modified to create mixtures of reactive oxygen species (ROS), ozone, hydroxyl radicals, and superoxide anions.
If you’re looking for air filtration systems for any environment, whether industrial, commercial, restaurant, or healthcare, Ohio Heating & Air Conditioning has an air cleaning solution for you.
We provide professional air filtration services individually tailored to meet the requirements of our clients. We offer a broad line of equipment to satisfy your air quality and air compliance requirements. Call 614-863-6666 to learn more.