Which rating indicates the highest energy efficiency?

A rating indicates the highest energy efficiency because energy efficiency ratings are typically defined on a scale where the highest letter grade represents the best performance in terms of energy use. In most systems for assessing energy efficiency, such as those used for appliances or buildings, an 'A' signifies that the item uses less energy compared to others rated below it. This classification helps consumers identify products that reduce energy consumption, thereby lowering utility costs and minimizing environmental impact. The gradation from A to D illustrates a decline in efficiency, with B being less efficient than A, and so on. Thus, selecting an item with an A rating is an optimal choice for those prioritizing energy savings.