PART 435—ENERGY EFFICIENCY STANDARDS FOR THE DESIGN AND CONSTRUCTION OF NEW FEDERAL LOW-RISE RESIDENTIAL BUILDINGS Authority: 42 U.S.C. 6831-6832; 6834-6836; 42 U.S.C. 8253-54; 42 U.S.C. 7101 et seq. Source: 53 FR 32545, Aug. 25, 1988, unless otherwise noted. Subpart A—Mandatory Energy Efficiency Standards for Federal Low-Rise Residential Buildings. Source: 71 FR 70283, Dec. 4, 2006, unless otherwise noted. § 435.1 Purpose and scope. (a) This part establishes energy efficiency performance standard for the construction of new Federal low-rise residential buildings as required by section 305(a) of the Energy Conservation and Production Act, as amended (42 U.S.C. 6834(a)). (b) This part also establishes a maximum allowable fossil fuel-generated energy consumption standard for new Federal buildings that are low-rise residential buildings and major renovations to Federal buildings that are low-rise residential buildings, for which design for construction began on or after May 1, 2025 (c) This part also establishes green building certification requirements for new Federal buildings that are low-rise residential buildings and major renovations to Federal buildings that are low-rise residential buildings, for which design for construction began on or after October 14, 2015. [71 FR 70283, Dec. 4, 2006, as amended at 79 FR 61571, Oct. 14, 2014; 89 FR 35433, May 1, 2024] § 435.2 Definitions. For purposes of this part, the following terms, phrases and words shall be defined as follows: Construction cost Design for construction Design for renovation DOE EISA-subject building or project https://www.gsa.gov/real-estate/design-and-construction/annual-prospectus-thresholds. 1/2 Federal agency Federal building Fiscal Year (FY) Fossil fuel-generated energy consumption e.g., ICC IECC IECC Baseline Building 2004 IECC Baseline Building 2009 IECC Baseline Building 2015 IECC Baseline Building 2021 Life-cycle cost Life-cycle cost-effective Low-rise residential building Major renovation Major renovation cost Major renovation of all Scope 1 fossil fuel-using systems in a building Major renovation of a Scope 1 fossil fuel-using building system or Scope 1 fossil fuel-using component New Federal building Proposed building Shift adjustment multiplier Technical impracticability (1) Not be feasible from an engineering design or execution standpoint due to existing physical or site constraints that prohibit modification or addition of elements or spaces; (2) Significantly obstruct building operations and the functional needs of a building, specifically for industrial process loads, critical national security functions, mission critical information systems as defined in NIST SP 800-60 Vol. 2 Rev. 1, and research operations, or (3) Significantly degrade energy resiliency and energy security of building operations as defined in 10 U.S.C. 101(e)(6) and 10 U.S.C. 101(e)(7) respectively. [71 FR 70283, Dec. 4, 2006, as amended at 72 FR 72571, Dec. 21, 2007; 76 FR 49285, Aug. 10, 2011; 82 FR 2867, Jan. 10, 2017; 87 FR 19613, Apr. 5, 2022; 89 FR 35433, May 1, 2024] § 435.3 Materials incorporated by reference. (a) Certain material is incorporated by reference into this subpart with the approval of the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that specified in this section, DOE must publish a document in the Federal Register [email protected], https://www.energy.gov/eere/buildings/building-technologies-office. [email protected], www.archives.gov/federal-register/cfr/ibr-locations.html. (b) ICC. http://www.iccsafe.org/. (1) ICC International Energy Conservation Code (IECC), 2004 Supplement Edition (“IECC 2004”), January 2005, IBR approved for §§ 435.2, 435.4, 435.5; (2) ICC International Energy Conservation Code (IECC), 2009 Edition (“IECC 2009”), January 2009, IBR approved for §§ 435.2, 435.4, 435.5. (3) ICC International Energy Conservation Code (IECC), 2015 Edition (“IECC 2015”), published May 30, 2014, IBR approved for §§ 435.2, 435.4, 435.5. (4) ICC 2021 International Energy Conservation Code (IECC), Redline Version, Copyright 2021, (“IECC 2021”), IBR approved for §§ 435.2, 435.4, and 435.5. [76 FR 49285, Aug. 10, 2011, as amended at 82 FR 2867, Jan. 10, 2017; 87 FR 19613, Apr. 5, 2022] § 435.4 Energy efficiency performance standard. (a)(1) All Federal agencies shall design new Federal buildings that are low-rise residential buildings, for which design for construction began on or after January 3, 2007, but before August 10, 2012, to: (i) Meet the IECC 2004 (incorporated by reference, see § 435.3), and (ii) If life-cycle cost-effective, achieve energy consumption levels, calculated consistent with paragraph (b) of this section, that are at least 30 percent below the levels of the IECC Baseline Building 2004. (2) All Federal agencies shall design new Federal buildings that are low-rise residential buildings, for which design for construction began on or after August 10, 2012, but before January 10, 2018 to: (i) Meet the IECC 2009 (incorporated by reference, see § 435.3), and (ii) If life-cycle cost-effective, achieve energy consumption levels, calculated consistent with paragraph (b) of this section, that are at least 30 percent below the levels of the IECC Baseline Building 2009. (3) All Federal agencies shall design new Federal buildings that are low-rise residential buildings, for which design for construction began on or after January 10, 2018, but before April 5, 2023 to: (i) Meet the IECC 2015, (incorporated by reference, see § 435.3), including the mandatory mechanical ventilation requirements in Section R403.6 of the IECC 2015; and (ii) If life-cycle cost-effective, achieve energy consumption levels, calculated consistent with paragraph (b) of this section, that are at least 30 percent below the levels of the IECC Baseline Building 2015. (4) All Federal agencies shall design new Federal buildings that are low-rise residential buildings, for which design for construction began on or after April 5, 2023 to: (i) Meet the IECC 2021, (incorporated by reference, see § 435.3); and (ii) If life-cycle cost-effective, achieve energy consumption levels, calculated consistent with paragraph (b) of this section, that are at least 30 percent below the levels of the IECC Baseline Building 2021. (b)(1) For new Federal low-rise residential buildings whose design for construction began before January 10, 2018, energy consumption for the purposes of calculating the 30 percent savings shall include space heating, space cooling, and domestic water heating. (2) For new Federal low-rise residential buildings whose design for construction began on or after before January 10, 2018, energy consumption for the purposes of calculating the 30 percent savings shall include space heating, space cooling, lighting, mechanical ventilation, and domestic water heating. (c) If a 30 percent reduction is not life-cycle cost-effective, the design of the proposed building shall be modified so as to achieve an energy consumption level at or better than the maximum level of energy efficiency that is life-cycle cost-effective, but at a minimum complies with paragraph (a) of this section. [71 FR 70283, Dec. 4, 2006, as amended at 72 FR 72571, Dec. 21, 2007; 76 FR 49285, Aug. 10, 2011; 82 FR 2867, Jan. 10, 2017; 87 FR 19613, Apr. 5, 2022] § 435.5 Performance level determination. (a) For new Federal buildings for which design for construction began on or after January 3, 2007, but before August 10, 2012, each Federal agency shall determine energy consumption levels for both the IECC Baseline Building 2004 and proposed building by using the Simulated Performance Alternative found in section 404 of the IECC 2004 (incorporated by reference, see § 435.3). (b) For new Federal buildings for which design for construction began on or after August 10, 2012, but before January 10, 2018, each Federal agency shall determine energy consumption levels for both the IECC Baseline Building 2009 and proposed building by using the Simulated Performance Alternative found in section 405 of the IECC 2009 (incorporated by reference, see § 435.3). (c) For new Federal buildings for which design for construction began on or after January 10, 2018 but before April 5, 2023 each Federal agency shall determine energy consumption levels for both the IECC Baseline Building 2015 and proposed building by using the Simulated Performance Alternative found in section R405 of the IECC 2015 (incorporated by reference, see § 435.3). (d) For new Federal buildings for which design for construction began on or after April 5, 2023 each Federal agency shall determine energy consumption levels for both the IECC Baseline Building 2021 and proposed building by using the Simulated Performance Alternative found in section R405 of the IECC 2021 (incorporated by reference, see [82 FR 2867, Jan. 10, 2017, as amended at 87 FR 19613, Apr. 5, 2022] § 435.6 Life-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures set out in subpart A of 10 CFR part 436. A Federal agency may choose to use any of four methods, including lower life-cycle costs, positive net savings, savings-to-investment ratio that is estimated to be greater than one, and an adjusted internal rate of return that is estimated to be greater than the discount rate as listed in OMB Circular Number A-94 “Guidelines and Discount Rates for Benefit-Cost Analysis of Federal Programs.” [71 FR 70283, Dec. 4, 2006, redesignated at 79 FR 61571, Oct. 14, 2014] Subpart B—Reduction in Scope 1 Fossil Fuel-Generated Energy Consumption Source: 89 FR 35434, May 1, 2024, unless otherwise noted. § 435.200 Scope 1 Fossil fuel-generated energy consumption requirement. (a) New EISA-Subject buildings. (i) For all leased buildings, the construction cost of the new building exceeds GSA's Annual Prospectus Thresholds that are found at www.gsa.gov/real-estate/design-construction/gsa-annual-prospectus-thresholds. (ii) For all Federally owned non-public buildings, the cost of the building is at least $2,500,000 (in 2007 dollars, adjusted for inflation). For the purposes of calculating this threshold, agencies must set the Bureau of Labor and Statistics CPI Inflation calculator to $2,500,000 in October of 2006 (to represent the value of the original cost threshold) and then set for October of the FY during which the design for construction of the project began or is set to begin. (b) Major renovations of EISA-Subject buildings. (2) This subpart applies only to the portions of the proposed building or proposed building systems that are being renovated and to the extent that the scope of the renovation permits compliance with the applicable requirements in this subpart. Unaltered portions of the proposed building or proposed building systems are not required to comply with this subpart. (3) For leased buildings, this subpart applies to major renovations only if the proposed building was originally built for the use of any Federal agency, including for the purpose of being leased by a Federal agency. (c) Federal buildings that are of the type included in Appendix A of this subpart New Construction and Major Renovations of all Scope 1 Fossil Fuel-Using Systems in an EISA-Subject Building. (i) Design for construction began during FY 2024 through FY 2029. For new construction or major renovations of all fossil fuel-using systems in an EISA-subject building, for which design for construction or renovation, as applicable, began during FY 2024 through 2029, the Scope 1 fossil fuel-generated energy consumption of the proposed building, based on the building design and calculated according to § 435.201(a), must not exceed the value identified in Tables A-1a to A-2a (if targets based on Scope 1 emissions are used) or Tables A-1b to A-2b (if targets based on kBtu of fossil fuel usage are used) of Appendix A of this subpart for the associated building type, climate zone, and fiscal year in which design for construction began. (A) Federal agencies may apply a shift adjustment multiplier to the values in Tables A-1a to A-2a or Tables A-1b to A-2b based on the following baseline hours of operation assumed in Tables A-1a to A-2a or Tables A-1b to A-2b. (B) To calculate the shift adjustment multiplier, agencies shall estimate the number of shifts for their new building and multiply by the appropriate factor shown below in Table 1 for their building type. The Scope 1 fossil fuel-generated energy consumption target for the building would be the value in either Tables A-1a to A-2a or Tables A-1b to A-2b multiplied by the multiplier calculated in the previous sentence. Table 1—Shift Adjustment Multiplier by Hours of Operation and Building Type Building activity/type Weekly hours of operation 50 or less 51 to 167 168 Admin/professional office 1 1 1.4 Bank/other financial 1 1 1.4 Government office 1 1 1.4 Medical office(non-diagnostic) 1 1 1.4 Mixed-use office 1 1 1.4 Other office 1 1 1.4 Laboratory 1 1 1.4 Distribution/shipping center 0.7 1.4 2.1 Nonrefrigerated warehouse 0.7 1.4 2.1 Convenience store 1 1 1.4 Convenience store with gas 1 1 1.4 Grocery store/food market 1 1 1.4 Other food sales 1 1 1.4 Fire station/police station 0.8 0.8 1.1 Other public order and safety 0.8 0.8 1.1 Medical office (diagnostic) 1 1 1.5 Clinic/other outpatient health 1 1 1.5 Refrigerated warehouse 1 1 1 Religious worship 0.9 1.7 1.7 Entertainment/culture 0.8 1.5 1.5 Library 0.8 1.5 1.5 Recreation 0.8 1.5 1.5 Social/meeting 0.8 1.5 1.5 Other public assembly 0.8 1.5 1.5 College/university 0.8 1.3 1.3 Elementary/middle school 0.8 1.3 1.3 High school 0.8 1.3 1.3 Preschool/daycare 0.8 1.3 1.3 Other classroom education 0.8 1.3 1.3 Fast food 0.4 1.1 2.1 Restaurant/cafeteria 0.4 1.1 2.1 Other food service 0.4 1.1 2.1 Hospital/inpatient health 1 1 1 Nursing home/assisted living 1 1 1 Dormitory/fraternity/sorority 1 1 1 Hotel 1 1 1 Motel or inn 1 1 1 Other lodging 1 1 1 Vehicle dealership/showroom 0.8 1.2 1.8 Retail store 0.8 1.2 1.8 Other retail 0.8 1.2 1.8 Post office/postal center 0.7 1.5 1.5 Repair shop 0.7 1.5 1.5 Vehicle service/repair shop 0.7 1.5 1.5 Vehicle storage/maintenance 0.7 1.5 1.5 Other service 0.7 1.5 1.5 Strip shopping mall 1 1 1 Enclosed mall 1 1 1 Bar/Pub/Lounge 1 1 1.4 Courthouse/Probation Office 1 1 1.4 (ii) Design for construction began during or after FY 2030. For new construction and major renovations of all Scope 1 fossil fuel-using systems in an EISA-subject building, the Scope 1 fossil fuel-generated energy consumption of the proposed building, based on building design and calculated according to § 435.201(a), must be zero. (2) Major Renovations of a Scope 1 Fossil Fuel-Using Building System or Component within an EISA-Subject Building shall follow the renovation requirements in section 4.2.1.3 of the applicable building baseline energy efficiency standards listed in § 435.4 substituting the term “design for construction” with “design for renovation” for the relevant date, and shall replace all equipment that is included in the renovation with all electric or non-fossil fuel-using ENERGY STAR or FEMP designated products as defined in § 436.42. For component level renovations, Agencies shall replace all equipment that is part of the renovation with all electric or non-fossil fuel-using ENERGY STAR or FEMP designated products as defined in § 436.42. (d) EISA-Subject buildings that are of the type not included in Appendix A of this subpart Process load buildings. (2) Mixed-use buildings. Equation 1: Scope 1 Fossil fuel generated energy consumption for a mixed-use building = the sum across all building uses of (the fraction of total floor building floor area for building use i times the allowable fossil fuel-generated energy consumption for building use i) Equation 1 may be rewritten as: § 435.201 Scope 1 Fossil fuel-generated energy consumption determination. (a) The Scope 1 fossil fuel-generated energy consumption of a proposed design is calculated as follows: Equation: Scope 1 Fossil Fuel-Generated Energy Consumption = Direct Fossil Fuel Consumption of Proposed Building/Floor Area Where: Direct Scope 1 Fossil Fuel-Generated Energy Consumption of Proposed Building Floor Area § 435.202 Petition for downward adjustment. (a) New Federal buildings major renovations of all Scope 1 fossil fuel-using systems, and major renovations of a Scope 1 fossil fuel-using building system or component in an EISA-subject building. (i) A statement from the Head of the Agency or their designee requesting the petition for downward adjustment for the building or renovation, that the building or renovation reduces consumption of Scope 1 fossil fuel energy consumption in accordance with the applicable energy performance standard to the maximum extent practicable and that each fossil fuel using product included in the proposed building that is of a product category covered by the ENERGY STAR program or FEMP for designated products is an ENERGY STAR product or a product meeting the FEMP designation criteria, as applicable; (ii) A description of the systems, technologies, and practices that were evaluated and unable to meet the required fossil fuel reduction including a justification of why achieving the Scope 1 fossil fuel-based energy consumption targets would be technically impracticable; and (iii) Any other information the agency determines would help explain its request. (2) The head of the agency designing the building, or their designee, must also include the following information in the petition: (i) A general description of the building or major renovation, including but not limited to location, use type, floor area, stories, expected number of occupants and occupant schedule, project type, project cost, and functional needs, mission critical activity, research, and national security operations as applicable; (ii) The maximum allowable Scope 1 fossil fuel energy consumption for the building from paragraphs (c) or (d) of this section; (iii) The estimated Scope 1 fossil fuel energy consumption of the proposed building; and (iv) A description of the proposed building's energy-related features, such as: (A) HVAC system or component type and configuration; (B) HVAC equipment sizes and efficiencies; (C) Ventilation systems or components (including outdoor air volume, controls technique, heat recovery systems, and economizers, if applicable); (D) Service water heating system or component configuration and equipment (including solar hot water, wastewater heat recovery, and controls for circulating hot water systems, if applicable); (E) Estimated industrial process loads; and (F) Any other on-site fossil fuel using equipment. (3) (i) Agencies may file one petition for a project with multiple buildings if the buildings are (A) Of the same building, building system, or component type and of similar size and location; (B) Are being designed and constructed to the same set of targets for fossil fuel-generated energy consumption reduction; and (C) Would require similar measures to reduce fossil fuel-generated energy consumption and similar adjustment to the numeric reduction requirement. (ii) The bundled petition must include the information in section (a) that pertains to all buildings, building systems or components included in the petition and an additional description of the differences between each of the buildings, building systems or components. The agency is only required to show work for adjustment once. (4) Petitions for downward adjustment should be submitted to [email protected], U.S. Department of Energy, FEMP, Director, Clean Energy Reduction Petitions, EE-5F, 1000 Independence Ave. SW, Washington, DC 20585-0121. (5) The Director will make a best effort to notify the requesting agency in writing whether the petition for downward adjustment to the numeric reduction requirement is approved or rejected, in 30 calendar days of submittal of a complete petition. If the Director rejects the petition or establishes a value other than that presented in the petition, the Director will forward the reasons for rejection to the petitioning agency. (b) Exclusions. Appendix A to Subpart B of Part 435 Maximum Allowable Fossil Fuel Generated Energy Consumption (a) For purposes of the tables in this appendix, the climate zones are listed in the performance standards required by § 435.4(a)(4)(i). (b) For purpose of appendix A, the following definitions apply: (1) Mobile Home (2) Multi-Family in 2-4 Unit Buildings (3) Multi-Family in 5 or More Unit Buildings (4) Single-Family Attached (5) Single-Family Detached Subpart C—Green Building Certification for Federal Buildings § 435.300 Green building certification. (a) If a Federal agency chooses to use a green building certification system to certify a new Federal building or a Federal building undergoing a major renovation and construction costs for such new building or major renovation are at least $2,500,000 (in 2007 dollars, adjusted for inflation), and design for construction began on or after October 14, 2015: (b) The system under which the building is certified must: (1) Allow assessors and auditors to independently verify the criteria and measurement metrics of the system; (2) Be developed by a certification organization that (i) Provides an opportunity for public comment on the system; and (ii) Provides an opportunity for development and revision of the system through a consensus-based process; (3) Be nationally recognized within the building industry; (4) Be subject to periodic evaluation and assessment of the environmental and energy benefits that result under the rating system; and (5) Include a verification system for post occupancy assessment of the rated buildings to demonstrate continued energy and water savings at least every four years after initial occupancy. (c) Certification level. [79 FR 61571, Oct. 14, 2014] Subpart D—Voluntary Performance Standards for New Non-Federal Residential Buildings [Reserved] Subpart E—Mandatory Energy Efficiency Standards for Federal Residential Buildings § 435.500 Purpose. (a) This subpart establishes voluntary energy conservation performance standards for new residential buildings. The voluntary energy conservation performance standards are designed to achieve the maximum practicable improvements in energy efficiency and increases in the use of non-depletable sources of energy. (b) Voluntary energy conservation performance standards prescribed under this subpart shall be developed solely as guidelines for the purpose of providing technical assistance for the design of energy conserving buildings, and shall be mandatory only for the Federal buildings for which design for construction began before January 3, 2007. (c) The energy conservation performance standards will direct Federal policies and practices to ensure that cost-effective energy conservation features will be incorporated into the designs of all new Federal residential buildings for which design for construction began January 3, 2007. [53 FR 32545, Aug. 25, 1988, as amended at 71 FR 70284, Dec. 4, 2006. Redesignated at 79 FR 61571, Oct. 14, 2014] § 435.501 Scope. (a) The energy conservation performance standards in this subpart will apply to all Federal residential buildings for which design of construction began before January 3, 2007 except multifamily buildings more than three stories above grade. (b) The primary types of buildings built by or for the Federal agencies, to which the energy conservation performance standards will apply, are: (1) Single-story single-family residences; (2) Split-level single-family residences; (3) Two-story single-family residences; (4) End-unit townhouses; (5) Middle-unit townhouses; (6) End-units in multifamily buildings (of three stories above grade or less); (7) Middle-units in multifamily buildings (of three stories above grade or less); (8) Single-section mobile homes; and (9) Multi-section mobile homes. [53 FR 32545, Aug. 25, 1988, as amended at 71 FR 70284, Dec. 4, 2006. Redesignated at 79 FR 61571, Oct. 14, 2014] § 435.502 Definitions. (a) ANSI (b) ASHRAE Handbook (c) ASTM (d) British thermal unit (Btu) (e) Building (1) That includes or will include a heating or cooling system, or both, or a domestic hot water system, and (2) For which a building design is created after the effective date of this rule. (f) Building design (g) Conservation Optimization Standard for Savings in Federal Residences (h) COSTSAFR (i) DOE (j) Domestic hot water (DHW) (k) Energy conservation measure (ECM) (l) Energy performance standard (m) Federal agency (n) Federal residential building (o) Life cycle cost (p) Point system (q) Practicable optimum life cycle energy cost (r) Project (s) Prototype (t) Residential building (u) Set of conservation options (v) Shading coefficient 1/8 (w) Total annual coil load [56 FR 3772, Jan. 31, 1991, redesignated at 79 FR 61571, Oct. 14, 2014] § 435.503 Requirements for the design of a Federal residential building. (a) The head of each Federal agency responsible for the construction of Federal residential buildings shall establish an energy consumption goal for each residential building to be designed or constructed by or for the agency, for which design for construction began before January 3, 2007. (b) The energy consumption goal for a Federal residential building for which design for construction began before January 3, 2007, shall be a total point score derived by using the micro-computer program and user manual entitled “Conservation Optimization Standard for Savings in Federal Residences (COSTSAFR),” unless the head of the Federal agency shall establish more stringent requirements for that agency. (c) The head of each Federal agency shall adopt such procedures as may be necessary to ensure that the design of a Federal residential building is not less energy conserving than the energy consumption goal established for the building. [53 FR 32545, Aug. 25, 1988, as amended at 71 FR 70284, Dec. 4, 2006. Redesignated at 79 FR 61571, Oct. 14, 2014] § 435.504 The COSTSAFR Program. (a) The COSTSAFR Program (Version 3.0) provides a computerized calculation procedure to determine the most effective set of energy conservation measures, selected from among the measures included within the Program that will produce the practicable optimum life cycle cost for a type of residential building in a specific geographic location. The most effective set of energy conservation measures is expressed as a total point score that serves as the energy consumption goal. (b) The COSTSAFR Program (Version 3.0) also prints out a point system that identifies a wide array of different energy conservation measures indicating how many points various levels of each measure would contribute to reaching the total point score of the energy consumption goal. This enables a Federal agency to use the energy consumption goal and the point system in the design and procurement procedures so that designers and builders can pick and choose among different combinations of energy conservation measures to meet or exceed the total point score required to meet the energy consumption goal. (c) The COSTSAFR Program (Version 3.0) operates on a micro-computer system that uses the MS DOS operating system and is equipped with an 8087 co-processor. (d) The COSTSAFR Program (Version 3.0) may be obtained from: National Technical Information Service; Department of Commerce; Springfield, Virginia 22161; (202) 487-4600 [53 FR 32545, Aug. 25, 1988, as amended at 56 FR 3772, Jan. 31, 1991. Redesignated at 79 FR 61571, Oct. 14, 2014] § 435.505 Alternative compliance procedure. (a) If a proposed building design includes unusual or innovative energy conservation measures which are not covered by the COSTSAFR program, the Federal agency shall determine whether that design meets or exceeds the applicable energy consumption goal in compliance with the procedures set forth in this section. (b) The Federal agency shall determine the estimated discounted energy cost for the COSTSAFR prototype building design, which is the most similar of the COSTSAFR prototypes to the proposed building design, by— (1) Printing out the COSTSAFR compliance forms for the prototype showing the points attributable to levels of various energy conservation measures; (2) Calculating the estimated unit energy cost on the compliance forms, on the basis of selecting the optimum levels on the compliance forms or otherwise in the User's Manual for each energy conservation measure; and (3) Multiplying the estimated unit energy cost by 100. (c) The Federal agency shall determine the estimated discounted energy cost for the proposed building design by— (1) Estimating the heating and cooling total annual coil loads of the proposed building design with the DOE 2.1C computer program on the basis of input assumptions including— (i) Shading coefficients of 0.6 for summer and 0.8 for winter; (ii) Thermostat setpoints of 78 degrees Fahrenheit for cooling, 70 degrees Fahrenheit for heating (6 am to 12 midnight), and 60 degrees Fahrenheit for Night Setback (12 midnight to 6 am, except for houses with heat pumps); (iii) The infiltration rate measured in air changes per hour as calculated using appendix B of the COSTSAFR User's Manual; (iv) Natural venting with a constant air change rate of 10 air changes per hour— (A) When the outdoor temperature is lower than the indoor temperature, but not above 78 degrees Fahrenheit; and (B) When the enthalpy of the outdoor air is lower than the indoor air. (v) Internal gains in accordance with the following table for a house with 1540 square feet of floor area, adjusted by 0.35 Btu/ft 2 Table 1—Internal Gain Schedule (Btu) Hour of day Sensible Latent 1 1139 247 2 1139 247 3 1139 247 4 1139 247 5 1139 247 6 1903 412 7 2391 518 8 4782 1036 9 2790 604 10 1707 370 11 1707 370 12 2277 493 13 1707 370 14 1424 308 15 1480 321 16 1480 321 17 2164 469 18 2334 506 19 2505 543 20 3928 851 21 3928 851 22 4101 888 23 4101 888 24 3701 802 (vi) Thermal transmittances for building envelope materials measured in accordance with applicable ASTM procedures or from the ASHRAE Handbook; (vii) Proposed heating and cooling equipment types included in COSTSAFR or having a certified seasonal efficiency rating; (viii) Weather Year for Energy Calculations (WYEC) weather year data (WYEC data are on tapes available from ASHRAE, 1791 Tullie Circle, N.E., Atlanta, Georgia 30329), or if unavailable, Test Reference Year (TRY) weather data (obtainable from National Climatic Data Center, 1983 Test Reference Year, (2) Estimating the discounted energy cost for the heating and cooling energy loads, respectively, according to the following equation— Where: Total Annual Coil Load = the total heating or cooling annual coil load calculated under paragraph (c)(1); Fuel Cost = the heating or cooling fuel cost calculated in accordance with sections 3.3.D and 3.3.E of the User's Manual; UPW* = the uniform present worth discount factor; selected from the last page of the compliance forms. Equipment Efficiency = the test seasonal efficiency rating of the heating and cooling equipment only (i.e., not including duct or distribution system losses). (3) Estimating the discounted energy cost for water heating and refrigerator/freezer energy consumption— (i) For equipment types covered by the COSTSAFR compliance forms, by multiplying the estimated unit energy cost by 100; or (ii) For equipment types not covered by COSTSAFR— Where: Fuel Cost and UPW* are as defined in paragraph (c)(2) of this section; Annual Energy Consumption is as calculated in 10 CFR 430.22; and Energy Factor is the measure of energy efficiency as calculated under 10 CFR 430.22 (iii) [Reserved] (4) Adding together the discounted energy costs calculated under paragraphs (c)(2) and (c)(3) of this section; (d) If the discounted energy cost of the proposed building design calculated under paragraph (c)(4) of this section is equal to or less than the discounted energy cost of the COSTSAFR prototype building design calculated under paragraph (b) of this section, then the proposed building design is in compliance with the applicable energy consumption goal under this part. [56 FR 3772, Jan. 31, 1991, redesignated at 79 FR 61571, Oct. 14, 2014] § 435.506 Selecting a life cycle effective proposed building design. In selecting between or among proposed building designs which comply with the applicable energy consumption goal under this part, each Federal agency shall select the design which, in comparison to the applicable COSTSAFR prototype, has the highest Net Savings or lowest total life cycle costs calculated in compliance with subpart A of 10 CFR part 436. [56 FR 3773, Jan. 31, 1991, redesignated at 79 FR 61571, Oct. 14, 2014]