Energy Cost Index

With all of the sales hype relating to air filters and indoor air quality how can you be sure that you have selected the proper air filter for your specific application?


There are industry test reports and the data published in manufactures literature or packaging — but will they provide a true indicator of a filter’s value over its life in your system?

Unfortunately the testing method prescribed today is an accelerated test — the test is performed in a matter of hours, hardly consistent with how the filter may perform over a matter of months or even years. Some manufactures use filter enhancements to fool the test into exhibiting an efficiency that in actual application can degrade in a time period of weeks or less. Their literature may even portray the filters performance based only upon the accelerated test data, misleading at best.


Enter the Energy Cost Index or ECI — a filter rating system that looks at the filters efficiency over its lifetime and the energy required to move air through that filter. ECI compares filters of similar construction, under the same conditions of operation and provides an indicator or TRUE performance. Specifically the formula is dollars per percent of filter efficiency. The lower the value, the better the filter.  The icons on the chart to the right note star values ranging from one star to five stars.



A filter with an ECI of five stars is a stellar performer — maintains its efficiency over its life and uses less energy to move air through the filter. It is in the top 20% of all filters evaluated. A four star filter has a lower ECI value, and the pattern continues down to one star, the poorest performers.  Your local Camfil Farr sales outlet can provide additional explanation on the Energy Cost Index. Through Camfil Farr’s R&D department they can provide ECI values on all Camfil Farr products and ECI values for products offered by other manufacturers.