Concerns over the indoor conditions have increased during recent years as a result of knowledge about indoor environmental quality on health, comfort and productivity of the workforce. The efficiency of the exhaust system is especially emphasised with a ventilated ceiling system where the exhaust is located at ceiling level. The removal efficiency of the total system must be guaranteed and the spread of impurities throughout the kitchen should be prevented. In the normal design practice, empirical knowledge of the existing installations together with rough heat load based calculation has been...