New refrigeration system configurations and other innovating technologies in retail supermarkets need to beconsidered to reduce energy use and greenhouse gas emissions. In supermarkets, there is a strong interactionbetween the refrigerated display cases, supermarket structure, internal machinery, customers, and the store’sHVAC system. The impact of these interactions on the energy and carbon emissions of a medium sized supermarket in Paris was modelled using EnergyPlus™. The results were calibrated against a typical UK store and validated against the Paris store. The effects of applying the technologies identified to have the greatest potential to reduce carbon emissions (changing the refrigerant to R-744, switching from gas to electrical heating and adding doors to chilled cabinets) were modelled. The impact of climate change on ambient temperature and the impact of changes to the grid conversion factor were predicted for the store in Paris from 2020 to 2050.