A frame (1) mounted filter assembly holder (2) in a ventilation arrangement (3) comprising a box shaped filter housing (4) with at least one air inlet opening (5) at a first side of the holder (2) and at least one air outlet opening (6) at a second side thereof. The housing (4) has first and second end walls (4a, 4b) and four side panels (4c, 4d, 4e, 4f), one of which (4f) is openable. The opening adjacent panels (4c, 4e) are traversed by first and second mutually facing inwardly protruding frame support elements (2a, 2b). At least one third frame support element (7) protrudes inwardly from the closed panel (4d) facing the opening in parallel to the first and second elements (2a, 2b) up to 10% of their extension with a frame (1) edge allowing separation. At least one fourth frame support element (8) protrudes inwardly from the openable panel (4f) such that it, when this panel (4f) is closed, extends parallel to the first and second elements (2a, 2b) with a frame (1) edge allowing separation.