The topics of thermal buildings, energy consumption and indoor air quality in cooling or ventilation systems is increasing in popularity as it is becoming more and more urgent to balance such needs. This paper reports on a study of different conditions and combinations of the cooling ability inside an open domain. The model is designed as a cavity cooled by three vertical panels that divide the space into four sub-domains. Three tendencies were studied: pure natural convection, forced convection and different mixing styles for the two cases. Complex flow structures are obtained in two cases: the injection or “assisting” case, in which dynamic and buoyancy forces are reinforced on the active wall, and the extraction or “opposing” case where the imposed flow is in the opposite direction of the buoyancy-induced flow. Results show mixing ability, which is the key parameter controlling the thermal field homogeneity for the cooling necessity. The possible 3-D flow shows that a simple analysis of the assisting and opposing effects is limited to predict the flow and thermal fields. Thanks to a wide-range variation of Rayleigh (Ra) and Reynolds (Re) numbers, the flow structures and thermal fields make it possible to categorise the different convection phenomena. The intensity of mixing ability is quantified in terms of Ra and Re results. Meanwhile, the conditions and threshold of the different domains are also developed. Different thermal discomfort conditions are highlighted, depending on the injection or extraction strategies. For some moderate injection intensity, a lower Nusselt (Nu) number appears to give a worse situation than in the case of pure natural convection.