This paper presents an experimental and numerical study on the energy performance of a water / soil heat exchanger coupled to a cooling floor. The system shows two galvanized steel water tanks embedded at a shallow depth of 2 m from the ground and each with a volume of 2 m(3). The experimental set up has enabled us to study these two cases: The first case considers the two tanks connected in parallel and coupled to the room, whereas the second case considers only one tank coupled to the cooling floor. An experimental device has been setup to measure the temperatures at different points as follow: indoor air temperature; surface temperature of the cooling floor; inlet and outlet tank temperatures. Experimental results were compared with those obtained from the simulation using Trnsys tools and a fair similarity was obtained. The numerical model made it possible to run a parametric study which revealed the most influential parameters on the energy efficiency of this system. A control strategy has been proposed to improve the energy efficiency of the water / soil heat exchanger. The control strategy used allows a lowering of the cooling floor surface temperature at the order of 2.5 degrees C, the indoor air temperature at the order of 6 degrees C and the water outlet temperature of the tank at 2 degrees C. The supply of night ventilation was introduced into the system with a regulation relative to the outside temperature. The control strategy of the underground tank systems and night ventilation gives an indoor air temperature reduction of 9 degrees C compared to the case without heat source, which gives a coverage rate of 65%. Results obtained on the feasibility of this technique in the Mediterranean climate are promising.