A ventilation system's cleanliness affects the quality of the air that it distributes. However, it is difficult for building managers to assess the relevance of having their systems cleaned and to choose among all the proposals from cleaning specialists since no objective method exists for assessing dust accumulation in the systems. The authors worked on developing a method for sampling the dusts in heating, ventilation and air conditioning (HVAC) ducts and for determining a criterion for initiating their cleaning. In the laboratory, they reproduced different dust accumulation levels in a metal duct that simulated HVAC systems, compared a method for sampling surface dust in ducts with those methods mentioned in the literature, compared the digital evaluation method to the visual method, and established application conditions. Each of the methods proved to be practicable by using its corresponding cleaning initiation criterion. However, some criteria need to be validated in future work. All the compared methods are described in the report.
