Every day we take more than 3,000 gallons of air into our lungs. We do this with 12 to 15 breaths every minute which translates to roughly six million breaths per year. For this reason alone, we should care about the quality of the air we breathe. Building managers should know this and the recent pandemic only stresses this point. That said, we need to take an evidence-based approach to air purification devices. Unless action is taken, it leads to unhealthy building conditions resulting in, lower worker morale, absenteeism, high energy costs, discomfort and even worse death.
Evidence-Based Approaches to Air Purification
Many different types of contaminants, pollutants, and allergens – compromise the quality of indoor air. The SARS CoV-2 – increases these concerns. Facilities managers and building owners need effective technologies and services to create & manage healthy working and occupiable spaces. The use of air purification devices can be part of an effective way in purifying and managing or controlling the air quality as well as the quality of the air purification product.
Several factors determine the effectiveness of air purification units (APU’s). For example, building pressurization, flow & exchange rates, the volume of air within the serviced areas affect outcomes, the cleanliness of the building and HVAC system impacts how successful APU’s are.
HVAC systems also play an important role. For example, HVAC factors affecting air quality include system design, air change rates, degree of coil fouling – Delta P, type, the placement of air purification devices relative to the system, the AHU and ductwork system hygiene cleanliness needs to be kept up and maintained regularly.
5 Basic Technologies for Air Purification:
Several technologies have been discovered and utilized in APU’s that can influence their functionality and performance. However, the overall effectiveness of APU can be optimized using a combination of technologies. Some of the more important technologies of controlling good IAQ is described below:
One of the more widely used air cleaning methods in both air purification devices as well as AHUs is filter media. Filter fibers trap and collect particulates. Depending on the size of the filter and the particulate a MERV rating of between 1 and 16 is expected. HEPA filtration is best at 99.97% at 0.03 microns though has application limitations due to high static pressure outcomes.
Electrostatic Precipitation, or ESP, charges particles so they get deposited onto oppositely charged metal plates. ESP is one of the most commonly used devices to control air pollution.
Air ionizers can be cost effective and easy to maintain technology that can enhance indoor air purification. These devices release both positively and negatively charged ions which target contaminants and cluster around them. This destroys or neutralizes the pathogen and indoor contaminants while making it easier to trap in filters.
Needlepoint Bipolar Ionization (NPBI) is one such device that mounts onto existing HVAC equipment. NPBI is effective in reducing indoor microbial contaminants like bacteria and fungi though can be limited effectiveness in removing volatile organic compounds (VOCs). Be careful with some NPBI emitting ozone a powerful oxidizing properties which can be harmful to building occupants.
Ultraviolet germicidal irradiation, or UVGI, releases ultraviolet energy into an enclosed space to destroy pathogens including bacteria, viruses, and mold.
Adsorption uses a charged compound to remove particles from the air. A highly porous surface charged with a bounding compound absorbs pollutants from flowing air thereby improving IAQ.
Advantages & Limitations to APU’s
The above APU’s have their advantages and limitations, of course, and no single technology is the “silver bullet” solution. However, a combination of these technologies provides the most effective path to cleaner air.
For example, HEPA filtration, charcoal filtration, UVC/G technologies, NPBI, HVAC system cleanliness, and IAQ monitoring devices when used together creates the best overall reduction of indoor contaminants for better building health.