The main method in the design practice of kitchen ventilation has been the calculation of the airflow rate, which is sufficient to extract the convective heat and contaminants. Undersized airflow rates could lead into indoor air problems and oversized ventilation system increases unnecessary energy consumption and the life-cycle costs of the system. In the most accurate design method, the design of a kitchen ventilation system is based on the airflow rate of the thermal plume. When the convection flow is calculated, the influence of the cooking process is ignored. In this paper, the actual measured plume characteristics of typical kitchen appliances are presented during cooking mode. The conducted measurements show that the generic plume equation gives a suitable platform for practical applications during the cooking mode as well. The critical factors affecting the accuracy are the estimation of the actual convection load and the proper adjustment of the virtual origin. (C) 2006 Elsevier B.V. All rights reserved.