; (B) the structure complies with the applicable provisions of the 2018 International Energy Conservation Code, as such standard or successor standard is in effect for purposes of this section pursuant to subsection (c); (C) in the case only of an existing structure, where determined cost effective, the structure has undergone rehabilitation or improvements, completed after the date of the enactment of this Act, and the energy consumption for the structure has been reduced by at least 20 percent from the previous level of consumption, as determined in accordance with energy audits performed both before and after any rehabilitation or improvements undertaken to reduce such consumption