Energy efficiency grade: it is a grading method to express the energy efficiency difference of household appliances. According to the relevant provisions of national standards, energy efficiency is divided into five grades in China's energy efficiency labeling at present. Grade 1 indicates that the energy saving of the product has reached the international advanced level and the energy consumption is the lowest; Grade 2 indicates that the product is more energy-efficient; Level 3 means that the product energy efficiency is the average level of China market; Level 4 means that the product energy efficiency is lower than the market average; Level 5 is the market access index of products, and products below this level are not allowed to be produced and sold.