Abstract
When an air cleaner is applied to a room with ventilated facilities to improve its indoor air quality, predicting the effect of selected air cleaner prior to installation is desired. This paper presents a diagram that roughly predicts the effect of installing an air cleaner at different ventilation rates based on the relationship between its single-pass efficiency and the rate of indoor air passage through it using a simple model that assumes instantaneous uniform diffusion of the contaminants of interest. In the results, the diagram was found to readily provide information about the required performance of air cleaners such as the clean air delivery rate（ CADR） and equivalent air change rate at the planning stage.
