Electrets and filtration : lab testing and field performance head to head

Ashrae 52.1 and 52.2 test standards have been of great value in providing classification methods to compare and contrast filter performances. But they were criticized too, becauset the exposure of electrostatic filtration media to "real world" air results in a performance below the efficiency determined by the Ashrae 52.2. Test.
So a field study has been carried out : the filtration properties of several types of commercially available HVAC bag or stiff-pocket filters were studied over a six-month period, then compared wtih the behaviour of the same types of filters when tested in lab according to the Ashrae 52.2. Test standard. Results are presented.