The refrigeration activity represents between 35% and 60% of the electrical consumption in a supermarket and the energy needs for positive temperature application are mainly due to the open vertical cabinets. The Standard ISO23953 defines precisely a way to measure the refrigeration duty (HER) of the refrigerated cabinets in laboratory conditions. Unfortunately, the laboratory cannot reproduce the thermal stratification of the store, so the HER has to be corrected by a coefficient of reduction. Tests on in 2 stores showed that the class 3 was representative to size the cooling pack but a coefficient of reduction between 0.8 and 0.9 could be applied for open vertical cabinets. To calculate the average energy consumption, a new coefficient was introduced to take into account the climatic variation inside the supermarket. This coefficient was determined as the ratio between the enthalpy of the humid air in store and the enthalpy of the reference value.