How do energy efficiency ratings work?

Like many ideas like this, it comes down to ratios. In the United States, a car's efficiency is expressed in miles per gallon; a higher number indicates that the car can travel farther on a given amount of fuel. This idea can be translated to energy: since gasoline must be burned in order to move a car, an automobile's fuel efficiency is essentially its energy efficiency.

The US uses the Energy Star rating to rate efficiency; the more stars it has, the more efficient it is. Energy efficiency ratings function similarly to miles per gallon; the higher the number, the more efficient it is, or the more work it gets done per unit of energy. From what I understand, they are frequently used in heating and cooling systems to measure how efficient an AC is working.

Regarding units, I'm sure it depends on the appliance being tested. For example, air conditioners use their cooling capacity in relation to the volts or watts that they require, while lightbulbs use BTUs (British Thermal Units) per hour, watts, or volts, depending on the location.

Energy efficiency ratings work by providing consumers with information about the energy consumption of a particular product, typically appliances or electronics. These ratings are standardized and often displayed as labels or tags on products. The ratings are based on various factors such as the energy consumption of the product during use, its efficiency in converting energy into useful work, and its environmental impact. Higher ratings indicate greater energy efficiency, meaning that the product consumes less energy to perform the same task compared to lower-rated products. This allows consumers to make informed decisions when purchasing products, helping them save energy, reduce utility bills, and minimize their environmental footprint.