A porous complex includes a base material that is a porous sintered body having air permeability, and a collection layer that is a sintered body provided on the base material and having air permeability, the collection layer exhibiting a dense foam network structure in a longitudinal section. The collection layer is formed by depositing and firing porous particles on the base material. This suppresses the penetration of the collection layer into pores of the base material and allows the porous complex to achieve high collection efficiency and low pressure loss.

A method to clean at least one secondary filter located inside an air filtration chamber of a ventilation system of a commercial kitchen is provided. The air filtration chamber is in gas communication with an exhaust conduit of the ventilation system. The method comprises: spraying a first liquid mixture including water and a cleaning agent towards an inlet surface of the at least one secondary filter; and spraying a second liquid mixture including water and a cleaning agent towards an outlet surface of the at least one secondary filter, wherein spraying the first liquid mixture and spraying the second liquid mixture is carried out sequentially. There is also provided a commercial cooking assembly comprising: at least one cooking appliance; and a ventilation system.