PALLADIO screw compressors are successfully applied in retrofit operations too, for substituting compressors of other brands in existing plants. This may happen either for substituting a broken compressor or increasing the energy efficiency of the cooling unit. Such improved efficiency is particularly high when a traditional compressor is substituted by a compressor of the PALLADIO KI series, with integrated inverter. The use of the inverter leads, in fact, to a sensitive improvement of the compressor efficiency at partial loads and, consequently, the average seasonal efficiency of the entire cooling unit. The eventual additional use of the option “authomatic Vi control” further improves the result, especially in those applications where the cooling unit operates under highly variable operating conditions. RefPower offers all the necessary support for the retrofit operation, also supplying specific conversion kits where necessary.