Mobile data centre unit (2, 3, 4) comprising: (i) at least one container, (ii) the at least one container comprising at least one rack for housing electronic equipment, (iii) the at least one rack comprising at least one heat exchanging means (7, 8) being adapted to transfer heat contained in an internal airflow, where the internal airflow has been heated up by the electronic equipment to be contained inside the rack to a fluid coolant, said heat exchanging means (7, 8) being located at at least one wall or element of the at least one rack, (iv) at least one coolant conduit (10, 11, 17, 18) comprising a piping system and being adapted to supply the heat exchanging means (7, 8) of the at least one rack with a fluid coolant and is further adapted to convey the heated coolant away through a reflux section of the coolant conduit, (v) wherein said at least one rack is an open rack and is designed and arranged in a way that the internal airflow within the rack is effectuated by active airflow generating means of at least a part of the electronic equipment to be contained in the rack, (vi) the at least one rack itself does not have additional fans for creating an airflow in the rack towards the heat exchanging means (7, 8), characterised in that (vii) the fluid coolant being supplied to the heat exchanging means (7,8) is a liquid coolant, and (viii) the heat exchanging means (7, 8) is designed as an air flow penetrable heat exchanging means (7, 8) wherein an airflow of 3000 m 3 /h creates a back pressure of less than 20 Pa, and (ix) the heat exchanging means (7, 8) is attached to a hinged door that can be reversibly swung open or closed and fluid connection lines forming a link between the piping system and the heat exchanging means (7, 8) are designed flexible, and (x) at least one external heat exchanging device (14, 15, 16) for cooling the liquid coolant heated during operation of the mobile data centre unit (2, 3, 4), and (xi) connecting means for connecting the at least one coolant conduit (10, 11, 17, 18) to the at least one external heat exchanging device (14, 15, 16) for conveying the heated liquid coolant to the at least one external heat exchanging device (14, 15, 16) and such that for transportation of the mobile data centre unit (2, 3, 4) the container and the at least one external heat exchanging device (14, 15, 16) are disconnectable from each other, hence forming two separately transportable subunits, (xii) wherein said at least one external heat exchanging device (14, 15, 16) is designed as a chiller device (14, 15) and/or as a hybrid cooler device, and (xiii) comprising a regulating control means providing control by varying the speed of at least one pump for circulating the liquid coolant so as to influence the liquid coolant flow rate. (i) at least one container, (ii) the at least one container comprising at least one rack for housing electronic equipment, (iii) the at least one rack comprising at least one heat exchanging means (7, 8) being adapted to transfer heat contained in an internal airflow, where the internal airflow has been heated up by the electronic equipment to be contained inside the rack to a fluid coolant, said heat exchanging means (7, 8) being located at at least one wall or element of the at least one rack, (iv) at least one coolant conduit (10, 11, 17, 18) comprising a piping system and being adapted to supply the heat exchanging means (7, 8) of the at least one rack with a fluid coolant and is further adapted to convey the heated coolant away through a reflux section of the coolant conduit, (v) wherein said at least one rack is an open rack and is designed and arranged in a way that the internal airflow within the rack is effectuated by active airflow generating means of at least a part of the electronic equipment to be contained in the rack, (vi) the at least one rack itself does not have additional fans for creating an airflow in the rack towards the heat exchanging means (7, 8), characterised in that (vii) the fluid coolant being supplied to the heat exchanging means (7,8) is a liquid coolant, and (viii) the heat exchanging means (7, 8) is designed as an air flow penetrable heat exchanging means (7, 8) wherein an airflow of 3000 m 3 /h creates a back pressure of less than 20 Pa, and (ix) the heat exchanging means (7, 8) is attached to a hinged door that can be reversibly swung open or closed and fluid connection lines forming a link between the piping system and the heat exchanging means (7, 8) are designed flexible, and (x) at least one external heat exchanging device (14, 15, 16) for cooling the liquid coolant heated during operation of the mobile data centre unit (2, 3, 4), and (xi) connecting means for connecting the at least one coolant conduit (10, 11, 17, 18) to the at least one external heat exchanging device (14, 15, 16) for conveying the heated liquid coolant to the at least one external heat exchanging device (14, 15, 16) and such that for transportation of the mobile data centre unit (2, 3, 4) the container and the at least one external heat exchanging device (14, 15, 16) are disconnectable from each other, hence forming two separately transportable subunits, (xii) wherein said at least one external heat exchanging device (14, 15, 16) is designed as a chiller device (14, 15) and/or as a hybrid cooler device, and (xiii) comprising a regulating control means providing control by varying the speed of at least one pump for circulating the liquid coolant so as to influence the liquid coolant flow rate.