Keeping the ventilation air clean is critical to achieve good IEQ. ASHRAE provides filtration guidance based on ranges of particle sizes, while green building certification standards like WELL provide requirements related to the concentration of specific particle sizes in occupied zones. Swegon GOLD air handling units are provided with Outside Air filters rated as MERV 13 as a standard feature. MERV 13 filters not only keep the air handler components clean and working at peak performance, they also reduce the concentration of pollutants in the Supply Air used for ventilation. Swegon models GOLD RX and GOLD PX also feature MERV 13 filters in the Return Air. According to ANSI/ASHRAE Standard 52.2-2017 “Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size”, filters rated as MERV 13 meet the following minimum filtration efficiency requirements:

• 50% or greater efficiency filtering particles in the range 0.30 to 1.0 m
• 85% or greater efficiency filtering particles in the range 1.0 to 3.0 m
• 90% or greater efficiency filtering particles in the range 3.0 to 10.0 m

The United States Environmental Protection Agency (EPA) describes particulate matter (particulate pollution) as follows:PM₁₀: inhalable particles, with diameters that are generally 10 micrometers (mm) and smaller. PM_2.5: fine inhalable particles, with diameters that are generally 2.5 micrometers (mm) and smaller. When specifying filters to reduce concentrations of PM_2.5 and PM₁₀, refer to the information in ASHRAE 52 to determine whether the MERV rating specified adequately filters PM₁₀ and PM_2.5.

Properly sealed filters prevent air – and particles in the air – from bypassing the filter media. Swegon GOLD air handling units include engineered filter racks that prevent filter bypass. CSN EN 1886 – “Ventilation for buildings – Air handling units – Mechanical performance” provides for the rating of filter bypass. Swegon GOLD air handling unit filter bypass is rated according to EN 1886 as F9, the highest possible rating, amounting to maximum filter bypass leakage rate of 0.5%, as a fraction of the nominal flow rate.