### Question
Can you define what annual fuel utilization efficiency means?


### Answer
**Annual fuel utilization efficiency** is defined as the following in *42 U.S.C. § 6291*:

> the efficiency descriptor for furnaces and boilers, determined using test procedures prescribed under section 6293 of this title and based on the assumption that all—


(A) weatherized warm air furnaces or boilers are located out-of-doors

#### 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**

