### Question
What is the definition of energy efficiency?


### Answer
The definition of **energy efficiency** is as follows in *42 U.S.C. § 6311*:

> the ratio of the useful output of services from an article of industrial equipment to the energy use by such article, determined in accordance with test procedures under section 6314 of this title

#### Citation:
  - *42 U.S.C. § 6311*
  - Heading: **CHAPTER 77-ENERGY CONSERVATION > SUBCHAPTER III-IMPROVING ENERGY EFFICIENCY > Part A&ndash;1-Certain Industrial Equipment**

