In this dataset, the field data from an integrated CO2 refrigeration system installed in a supermarket located north of the capital of Lisbon was shared. The scheme of the refrigerating system is provided in Figure 1-2, while the installed capacities and main components characteristics are listed in Table 1 and Table 2, respectively.The system can meet AC demand by direct evaporation in the air handling units (AHUs) units. Due to the summer season and warm ambient temperatures, AC is applied to meet the temperature set-point inside the shop (Figure 2). Moreover, compressor racks and AHU units are shown only with a single symbol. The system consists of the LT compressor rack (three semi-hermetic compressors), the MT compressor rack (four semi-hermetic compressors), and the parallel compressor (PC) rack (four semi-hermetic compressors) for AC; a gas cooler (GC); MEs; liquid receiver, MT suction line accumulator; LT and MT evaporators, expansion valves (EVs), oil recovery system, and two rooftop AHUs. For each compressor rack, one compressor is equipped with an inverter to allow smoother capacity modulation. The PCs are organized in such a way that they can manage different suction pressures according to heat pump functionality and/or PC. The ME blocks were sized for vapor pre-compression (HPE) according to the climate profile of the region and liquid return (LE) in the case of liquid leaving the MT evaporators. The AHU comprises two identical rooftop units. These units deliver the entire heating and cooling capacity of the supermarket. CO2 is directly applied inside the heating and cooling coils of the AHUs. SH demand can be covered seamlessly by means of a 3-way valve allowing high pressure CO2 gas supply to the heating coils in the AHU. An increasing high pressure and separate heat pump functionality can be utilized to cover high heating demands. In summertime, the AHU’s cooling coils can be operated in two different ways: the first alternative is the DX downstream of the GC, i.e., the refrigerant expands from the high-pressure side directly into the coils where it is evaporated and enters the liquid receiver. The second alternative is using a low-pressure lift high entrainment ratio ejector (AC ejector). The AC ejector sucks the whole vapor of the AC evaporators to compress it to the receiver pressure level. The first alternative was in operation during the time period analyzed in this study; thus, the effect of AC ejectors will not be mentioned in the following sections. High-pressure lift and liquid ejectors are applied to return both vapor and liquid from the suction line accumulator to the liquid receiver.