Standards are used as a measurement reference for the definition of the rating systems, used in different countries worldwide, to indicate energy efficiency classes of household electrical appliances, e.g. A to G classes used in the European Union Energy Label and compliance with the European Union Energy Labelling Directives. The standards and their consequent recognition at country level in specific laws and regulations, e.g. the above Energy Labelling Directives in the EU, have made energy efficiency an important factor in market competition as consumers look at energy performance when choosing an appliance. The EN standards for the purpose of energy labelling are based on IEC standards (ISO standards for refrigerators and freezers) and help international comparison as countries like China are also using the same international standards for Chinese energy labelling laws