31, 2019, or (B) $250 for each exterior door. (5) Limitation on residential energy property expenditures The amount of the credit allowed under this section by reason of subsection (a)(2) shall not exceed— (A) in the case of any energy-efficient building property— (i) for any item of property described in subparagraph (A), (B), or (C) of subsection (d)(3), $600, and (ii) for any item of property described in subparagraph (D) or (E) of such subsection, $400, and (B) in the case of any qualified natural gas, propane, or oil furnace or hot water boiler (as defined in subsection (d)(4)), an amount equal to— (i) $600 for a hot water boiler, and (ii) in the case of a furnace, an amount equal to the sum of— (I) $300, plus (II) if the taxpayer is converting from a non-condensing furnace to a condensing furnace, $300. , (3) in subsection (c)— (A) in paragraph (2)— (i) by striking subparagraphs (A) and (B) and inserting the following: (A) applicable Energy Star program requirements, in the case of an exterior window, a skylight, or an exterior door, and , (ii) by redesignating subparagraph (C) as subparagraph (B), and (iii) in subparagraph (B), as so redesignated, by striking 2009 International and all that follows through Act of 2009 and inserting 2015 IECC (as defined in section 45L(b)(5)) , (B) in paragraph (3)— (i) in subparagraph (B), by adding and at the end, (ii) in subparagraph (C), by striking , and and inserting a period, and (iii) by striking subparagraph (D), and (C) by adding at the end the following new paragraph: (5) Labor costs The term qualified energy efficiency improvements includes expenditures for labor costs properly allocable to the onsite preparation, assembly, or original installation of any energy efficient building envelope component. , (4) in subsection (d)— (A) in paragraph (2)(A)— (i) in clause (i), by adding or at the end, (ii) in clause (ii), by striking , or and inserting a period, and (iii) by striking clause (iii), (B) in paragraph (3)— (i) by striking subparagraph (A) and inserting the