Mass. Gen. Laws ch. 164 § 107
To establish a calorific standard for gas, the department may from time to time, after notice and a public hearing, determine how many British thermal units shall thereafter be required of gas supplied to their consumers by gas companies or municipal lighting plants.
Upon application of a gas company, or the mayor or selectmen of a municipality in which a municipal lighting plant is established, the department may exempt such gas company or municipal lighting plant from furnishing gas of the calorific standard established as aforesaid and, if in its judgment the public welfare and local conditions warrant, may determine how many British thermal units ought thereafter to be required of gas supplied to its consumers by such company or plant, and on what terms or conditions, which requirement shall thereafter be observed by such company or plant while such exemption continues or until some other standard is established in the same manner.
Mass. Gen. Laws ch. 164, § 107