In time, ventilation ducts and accessories get dirty and this may lead to malfunction of ventilationequipment, fire hazard and especially a decrease in supply air quality. Repeated cleaningof the components can prevent these adverse effects. The frequency of cleaning dependson how easily different components get dirty. Although reduced dirtiness in ventilation ductsurfaces also reduces cleaning demands, there is still no accepted test method to determine thepropensity of the components to accumulate dirt.VTT Technical Research Centre of Finland has developed a fast component-related testmethod called KOLITEST. With this method, HVAC-components can be arranged into orderof superiority by their propensity to accumulate dirt.The aim of this study was to establish the KOLITEST -method's needs for further developmentand carry out a development plan. The development plan included examination of thefunction and quality of old KOLITEST -equipment, the creation of new KOLITEST -equipment and testing their suitability for testing ventilation ducts and accessories for theirpropensity to accumulate dirt.Several tests were made with the new KOLITEST -equipment. The test results showed thatthe reproducibility of the new KOLITEST -method is good and different kind of dust accumulationrates can be produced into the test section of the KOLITEST -equipment. The renewedKOLITEST -method can be used as a test method to determine the propensity of the componentsto accumulate dirt. In the future this method will be used in a study of soil repellent materials.Producers of ventilation ducts and accessories will benefit most from this test method.Component manufacturers can receive information about their products and their tendency toget dirty. These results can be used in their product development.