### Question
How is the "energy efficiency" defined?


### Answer
The term **energy efficiency** is defined in *42 U.S.C. § 6291* as follows -

> the ratio of the useful output of services from a consumer product to the energy use of such product, determined in accordance with test procedures under section 6293 of this title

#### Citation:
  - *42 U.S.C. § 6291*
  - Heading: **CHAPTER 77-ENERGY CONSERVATION > SUBCHAPTER III-IMPROVING ENERGY EFFICIENCY > Part A-Energy Conservation Program for Consumer Products Other Than Automobiles**

