the Secretary shall promulgate a regulation to allow the allocation of the deduction to the person primarily responsible for designing the property in lieu of the owner of such property. Such person shall be treated as the taxpayer for purposes of this section. . (6) Alternative deduction for energy efficient building retrofit property repealed (A) In general Section 179D is amended by striking subsection (f). (B) Restoration of text relating to interim rules for lighting systems Section 179D is amended by inserting after subsection (e) the following: (f) Interim rules for lighting systems Until such time as the Secretary issues final regulations under subsection (d)(1)(B) with respect to property which is part of a lighting system— (1) In general The lighting system target under subsection (d)(1)(A)(ii) shall be a reduction in lighting power density of 25 percent (50 percent in the case of a warehouse) of the minimum requirements in Table 9.5.1 or Table 9.6.1 (not including additional interior lighting power allowances) of Standard 90.1–2007. (2) Reduction in deduction if reduction less than 40 percent (A) In general If, with respect to the lighting system of any building other than a warehouse, the reduction in lighting power density of the lighting system is not at least 40 percent, only the applicable percentage of the amount of deduction otherwise allowable under this section with respect to such property shall be allowed. (B) Applicable percentage For purposes of subparagraph (A), the applicable percentage is the number of percentage points (not greater than 100) equal to the sum of— (i) 50, and (ii) the amount which bears the same ratio to 50 as the excess of the reduction of lighting power density of the lighting system over 25 percentage points bears to 15. (C) Exceptions This subsection shall not apply to any system— (i) the controls and circuiting of which do not comply fully with the mandatory and prescriptive requirements of Standard 90.1–2007 and which do not include provision for bilevel switching