standards . (2) Applicable standards Section 45L of such Code, as amended by subsection (a), is amended by adding at the end the following new subsection: (g) Applicable standards For purposes of this section, the term applicable standards means, with respect to any dwelling unit, the standards in effect for residential building energy efficiency under the International Energy Conservation Code on the first day of the taxable year in which construction for the dwelling unit commenced. . (c) Effective date The amendments made by this section shall apply to homes acquired after December 31, 2016. 328. Permanent extension and refundability of credit for nonbusiness energy property (a) Permanent extension Section 25C of the Internal Revenue Code of 1986 is amended by striking subsection (g). (b) Update of standards (1) Qualified energy efficiency improvements (A) In general Section 25C(c)(2)(C) of the Internal Revenue Code of 1986 is amended by striking the prescriptive criteria for such component established by the 2009 International Energy Conservation Code, as such Code (including supplements) is in effect on the date of the enactment of the American Recovery and Reinvestment Tax Act of 2009 and inserting the applicable IECC standards . (B) Applicable IECC standards Section 25C(c) of such Code is amended by adding at the end the following new paragraph: (5) Applicable IECC standards For purposes of this section, the term applicable IECC standards means, with respect to any building envelope component, the prescriptive criteria for such component in effect under the International Energy Conservation Code on the first day of the taxable year for which the credit is allowed. . (2) Energy efficient property (A) Heat pumps and air conditioners (i) In general Section 25C(d)(3) of the Internal Revenue Code of 1986 is amended by striking the Consortium for Energy Efficiency, as in effect on January 1, 2009 each place it appears and inserting the applicable CEE standards . (ii) Applicable CEE standards Section 25C(d) of