Filtration In Chico, Paradise, CA, And Surrounding Areas
HVAC Air Filtration: Best Of Both Worlds
Among the common misconceptions about air filtration technology is that air filters with superior particle capture efficiency do not always have good energy efficiency and vice-versa. Air filters do have an effect on both indoor air quality (IAQ) and the energy consumption of a building’s HVAC system. However, the two do not have to be mutually exclusive, especially if filters with electret-treated media are used.
How Air is Filtered
To understand how different types of air filtration technology affect IAQ and HVAC system energy consumption, it is best to know how air filters work. Air filters capture airborne particles on the filter media, which is the material within the filter that removes impurities and pollutants from the air. For air filters to capture particles on the filter media, the particle must collide with or be removed by the filter media fibers and must continue to adhere to the media fibers. There are four primary methods of mechanical particle capture:
- Impingement: As air flows through a filter, it changes direction to flow around the filter fibers. Because of their inertia, larger particles resist change in direction and attempt to continue in their original direction, thus colliding with and adhering to the fibers.
- Interception: A particle follows the air stream and contacts the fiber as it passes around it. If the forces of attraction between the fiber and the particle are greater than the force of the airflow to dislodge it, the particle will stick to the fiber. Interception is enhanced when the size of the fiber is closest to the size of the particle.
- Diffusion: As air passes through the filter media, minute particles move from areas of higher concentration and take an erratic path called Brownian Motion. This increases the probability that particles will contact the fiber and stay attached to them. Diffusion works best with fine filter fibers and very low air velocities.
- Straining: This occurs when the smallest dimension of a particle is greater than the distance between adjoining filter media fibers.
