When evaluating multiple filters against each other, it is very common to focus on the initial DP as the primary indicator of Total Cost of Ownership (TCO) of a given product. However, that is only one part of the story. As it turns out, the Dust Holding Capacity (DHC), or more generically, the amount of dirt and other particulates a filter can hold until it reaches its maximum recommended operating pressure is just as important.
In the chart below, we show 3 products with 3 different performance levels – the first is a pleat with an initial DP of 0.4” w.c. and a DHC of 75g. The second pleat has ½ the initial DP but the same DHC, and the third product has double the DHC but the same initial DP as the first pleat. In this scenario, we find that products 2 and 3 have essentially the exact same TCO, both saving 19% compared to the first product when changed out on the same interval.
Energy provider PG&E recommends regular filter maintenance as the #1 way to save energy on commercial and industrial buildings. Despite that, there are products out there that advertise a longer life than standard products, which is driven by a higher than average DHC. The best way to take advantage of that performance is not to change it out at its final life, but instead to change it out early. While you could save around 45% on your filters annually by using the better filter longer, it actually drives up the TCO by around 5% in this example because of increased energy usage. Changing the same filter out at 4 months instead allows for TCO savings of 17%
Always to remember the filters are a part of a system and each filter should not be looked at individually. Just because you have a spot for a prefilter does not mean you need one. Products with high amounts of media like 4-V bank mini pleats in low dust applications are probably better without a prefilter to reduce the overall system pressure drop. On the other hand, high dust applications should have a higher MERV (11-13) pre or secondary filter to protect the more expensive efficiency filter to make it last. Naturally, there are many “in-between” installations that require a MERV 8-10 prefilter.