This part of ISO 13579 specifies a general methodology for measuring energy balance and calculating the efficiency of the process involving reheating furnaces for steel as designed by furnace manufacturers. This general methodology includes:  measurement methods;  calculations (general calculation);  energy balance and efficiency calculation evaluation report. This part of ISO 13579 is not applicable to any efficiencies related to the process itself outside of reheating furnaces for steel (e.g. in a rolling mill process, the reheating furnace is the only part covered by this part of ISO 13579).