; and (G) not include improvements to swimming pools or hot tubs or any other expenditure specifically excluded by the Secretary. (2) Approved modeling software The contractor shall use modeling software certified by RESNET as following the software verification test suites in section 4.2.1 of RESNET Publication No. 13–001, or under equivalent standards approved by the Secretary for this purpose, and shall have the ability at a minimum to assess the savings associated with all the measures for Home Energy Savings Retrofit Rebate Program. (3) Exception For purposes of paragraph (1)(D)(ii), installation of gas-fired appliances shall comply with requirements of the National Fuel Gas Code (ANSI Z223.1/NFPA 54) and applicable installation requirements in lieu of performance of combustion tests outside those required by the National Fuel Gas Code (2012 Edition) and the International Fuel Gas Code (2012 Edition). (e) Energy use reduction (1) Determination of energy use reduction (A) In general The reduction in energy use for any residence shall be determined by modeling the annual predicted percentage reduction in total energy consumption or costs for heating, cooling, hot water, and permanent lighting. It shall be modeled using computer modeling software approved under subsection (d)(2) and calibrated according to subparagraph (C) of this paragraph. (B) Energy costs For the purposes of subparagraph (A), the energy cost per unit of fuel for each fuel type shall be determined by dividing the total actual energy bill (subtracting taxes and fees) for the residence for that fuel type for the most recent available 12-month period by the total energy units of that fuel type used over the same period. (C) Baseline energy use For the purposes of subparagraph (A), the software model that establishes the baseline energy use and predicted energy savings shall be calibrated according to the procedures set forth in sections 3 and 4 of ANSI/BPI Standard BPI–2400–S–2012: Standard Practice for Standardized Qualification of Whole-House