### Question
How does the law define heat input?


### Answer
Under *40 CFR § 52.01*, **heat input** is defined as:

> the total gross calorific value (where gross calorific value is measured by ASTM Method D2015-66, D240-64, or D1826-64) of all fuels burned.

#### Citation:
  - *40 CFR § 52.01*
  - Heading: **Title 40—Protection of Environment > PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS > Subpart A—General Provisions > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)**

