In this article, researchers Matthew Ward and Jeffrey Siegel studied the effects of bypass air on filter performance. Their findings suggest that most HVAC filters with sizeable bypass gaps actually perform worse with age, which goes against conventional knowledge. Additionally, they found that high-efficiency filters may not justify their expense if they have sizable gaps.

As the researchers note, “any economic analysis seeking to optimize the cost effectiveness of filtration must either include costs for minimizing bypass or account for reduced efficiency caused by bypass.”

The results also show that respirable particles are not appreciably removed in the gap, which means that bypass is significantly detrimental to indoor air quality. An HVAC design that employs high efficiency filters to prevent health problems associated with indoor fine particles may fail to perform as intended due to bypass. The results presented in this paper can provide a basis to quantify the effect of bypass on indoor air quality.

For more information on the effects of gaps and bypass on filter performance, contact Arthur Dwight, Carolina IAQ’s principal and engineering director.

Read the full text of the research article here.