This paper focuses on evaluating the performance of a wall displacement ventilation system and a new impinging jet ventilation system. Ventilation efficiency, local mean age of air and other characteristic parameters were experimentally and numerically obtained for a mock-up classroom. The internal heat load of 25 person-simulators were set to represent a crowded classroom in order to investigate any indoor climate problems caused by increased cooling loads. Four ventilation strategies were compared in a previous paper [1] but here we have chosen only the two systems mentioned. In addition to a large number of costly experiments we used CFD simulations to study certain parameters in more detail and explore the results for other situations such as industrial ventilation. The results presented here are part of a larger search programme to develop alternative and efficient systems for new challenging situations of room airflow distribution.