Method for evaluating the cleaning state of an aeration and/or conditioning plant of a room

A computer implemented method for evaluating cleaning status of an aeration and/or conditioning plant of a room, the plant having ducts and at least an air vent inside said room, comprising at least the steps of:

• performing a first powder concentration measurement (S), obtained as an average of a plurality of powder concentration measurements performed during a first predetermined time period (ΔT1) of plant inactivity, inside said room at said air vent;
• performing measurements of a first temperature (Ti) inside the room and a second temperature (Te) in outer environment to determine said first predetermined time period (ΔT1) to be set in a period where Te<Ti;
• performing a series of powder concentration measurements during a second predetermined time period (ΔT2) at starting of the plant, inside said room at said air vent;
• extracting a value of maximum concentration (P) from said series of measurements;
• calculating a duct cleaning index (DCI) as difference between said value of maximum concentration (P) and said first concentration measurement (S);
• indicating a dirty state of the ducts if said DCI is greater than or equal to a first predetermined threshold value (TOLL1);
• and
• establishing an intervention time for performing maintenance based on a value of the DCI.