Abstract: An example method includes measuring a plurality of metrics of performance of a refrigeration device, analyzing the plurality of metrics for changes in efficiency of operation of the refrigeration device, and based on the changes in efficiency of operation of the refrigeration device being reductions in efficiency, outputting an indicator of a refrigerant leak of the refrigeration device. In one instance, an example system includes a temperature sensor externally mounted to a line, of a refrigerant loop, that couples components of a refrigeration device, and a monitoring device, in communication with the temperature sensor, for (i) sampling the temperature sensor and generating temperature readings of the line, (ii) analyzing the temperature readings over time; and (iii) outputting an indicator of a refrigerant leak of the refrigeration device based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device.