Final answer:
The rating system for appliance efficiency is called the Energy Efficiency Rating (EER) or the Energy Star Rating, with higher EER values indicating more energy-efficient appliances.
Step-by-step explanation:
The rating system used to measure the efficiency of appliances is known as the Energy Efficiency Rating (EER) or the Energy Star Rating. The EER gives an indication of how well an appliance converts energy into work and is especially relevant for air conditioners and refrigerators. This rating is expressed in mixed units of British Thermal Units (Btu) per hour divided by the power input in watts. The higher the EER, the more energy efficient the appliance is considered to be. For example, room air conditioners might have EERs ranging from 6 to 12, with higher EERs indicating better efficiency and lower operating costs.
However, these appliances may have a higher purchase price. The Energy Star Rating is a simplified system used in countries like Australia, Canada, New Zealand, and the U.S., where appliances are rated on a scale of 1 to 5 stars, with more stars indicating greater energy efficiency.