The effectiveness of indoor air quality in buildings heavily relies on the efficiency of HVAC air filtration systems. Originally designed to combat dust and dirt accumulation, these systems have adapted to address evolving concerns such as gaseous, chemical, biological, and radiological contaminants. This adaptability has become even more significant in light of the COVID-19 pandemic’s emphasis on clean, conditioned air.
Manufacturers have upgraded existing filtration systems to enhance their performance, introducing new technologies capable of effectively reducing various types of contaminants. This provides facility managers with a range of options to choose from. To make informed decisions, managers must grasp the kinds of airborne pollutants present in their facilities and identify the most suitable systems for their elimination.
Three main categories of contaminants exist within building HVAC systems: particulate, gaseous, and biological. Each category necessitates a tailored system design to effectively reduce its concentration within the HVAC system.
- Mechanical Air Filters:
Mechanical air filters are the most commonly used filtration systems in HVAC systems. They employ materials like spun glass or non-woven substances to strain and capture particles. Filter efficiency, measured through the Minimum Efficiency Reporting Value (MERV), determines their performance. Higher MERV ratings indicate better filtration. For instance, MERV ratings between 5 and 8 remove 80 to 95 percent of particles sized three microns or larger. High Efficiency Particulate Air (HEPA) filters offer even greater filtration efficiency, capturing up to 99.7 percent of contaminants sized 0.3 microns or larger. However, higher MERV ratings can increase airflow resistance, demanding higher fan energy usage. - Gas-Phase Systems:
Mechanical filters fall short in removing gaseous contaminants, necessitating gas-phase air cleaners that operate through adsorption. These systems use activated charcoal to capture chemical vapors, volatile organic compounds, and other gases. They’re suitable for areas with routine gas emissions or pollution sources near fresh air intakes. - UV Light Systems:
UV-C light, within specific wavelengths and intensities, can kill or deactivate biological contaminants. UV light systems are positioned within HVAC ducts, emitting UV-C light to target bacteria, viruses, and fungi. While proven effective for coil disinfection, their use against airborne pathogens is still under research. Safety precautions are essential due to potential harm to skin and eyes. - Outside the Box Solutions:
Beyond HVAC-centric solutions, standalone options like portable air cleaners and upper-room disinfection systems offer flexibility. Portable air cleaners have their own filtration systems and can function independently of the HVAC system, while upper-room disinfection systems use UV-C light fixtures installed in room ceilings to target airborne contaminants, reducing transmission rates.
In conclusion, no single solution suits all facilities. Assessing contamination levels and cleanliness requirements is pivotal in selecting the appropriate air filtration strategy. With a variety of options available, facility managers can tailor systems or even combine multiple solutions for optimal air quality improvement.