This part of this European Standard describes the methodologies to be used in a laboratory air tight chamber to test prototype or commercial air cleaner systems with a maximum flow rate of 1,000 m³/h used for the indoor air remediation. It applies to the treatment of atmospheres that are representative of the air inside buildings and workplaces. This protocol applies solely to photocatalytic systems alone or to combined systems that include a photocatalytic function. This photocatalytic function is demonstrated by verifying the mineralisation of model VOCs to form CO2.