When used in this Part, the term utility includes any such gas corporation, electric corporation, gas and electric corporation, steam corporation, municipality, or any entity that, in any manner, sells or facilitates the sale, furnishing or provision of gas or electric commodity to residential customers, including energy services companies and owners of submetered residential buildings; provided, however, that the term does not include any municipality that is exempt from commission regulation by virtue of section 1005(5)(g) of the Public Authorities Law.