PART 460—ENERGY CONSERVATION STANDARDS FOR MANUFACTURED HOMES Authority: 42 U.S.C. 17071; 42 U.S.C. 7101 et seq. Source: 87 FR 32818, May 31, 2022, unless otherwise noted. Subpart A—General § 460.1 Scope. This subpart establishes energy conservation standards for manufactured homes as manufactured at the factory, prior to distribution in commerce for sale or installation in the field. Manufacturers must apply the requirements of this part to a manufactured home subject to § 460.4(b) that is manufactured on or after 60 days after publication of final enforcement procedures for this part. DOE will amend this section to include the specific compliance date, once known. Manufacturers must apply the requirements of this part to a manufactured home subject to § 460.4(c) that is manufactured on or after 180 days after publication of final enforcement procedures for this part. DOE will amend this section to include the specific compliance date, once known. [90 FR 28878, July 2, 2025] § 460.2 Definitions. Adapted from section R202 of the 2021 IECC and as used in this part— 2021 IECC Access (to) Air barrier Automatic Building thermal envelope Ceiling Climate zone Conditioned space Continuous air barrier Door Dropped ceiling Dropped soffit Duct Duct system Eave Equipment Exterior ceiling Exterior floor Exterior wall Fenestration Floor Glazed or glazing Heated water circulation system Insulation Manual Manufactured home Manufacturer Opaque door R-value (thermal resistance) 2 Rough opening Service hot water Skylight Skylight well Solar heat gain coefficient (SHGC) State Thermostat U-factor (thermal transmittance) 2 U o (overall thermal transmittance) 2 Ventilation Vertical fenestration Wall Whole-house mechanical ventilation system Window Zone § 460.3 Materials incorporated by reference. Certain material is incorporated by reference into this part 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, the U.S. Department of Energy (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. (a) ACCA. www.acca.org (1) ANSI/ACCA 2 Manual J-2016 (ver 2.50) (“ACCA Manual J”), Manual J-Residential Load Calculations, Eight Edition, Version 2.50, Copyright 2016; IBR approved for § 460.205. (2) ANSI/ACCA 3 Manual S-2014 (“ACCA Manual S”), Manual S- Residential Equipment Selection, Second Edition, Version 1.00, Copyright 2014; IBR approved for § 460.205. (b) HUD User, www.huduser.gov/portal/publications/pdrpubli.html. (1) HUD User No. 0005945, Overall U-Values and Heating/Cooling Loads—Manufactured Homes, February 1, 1992 (available from www.huduser.org/portal/publications/manufhsg/uvalue.html (2) [Reserved]. § 460.4 Energy conservation standards. (a) General. (b) Tier 1. i.e., (c) Tier 2. i.e., Subpart B—Building Thermal Envelope § 460.101 Climate zones. Manufactured homes subject to the requirements of this subpart must comply with the requirements applicable to one or more of the climate zones set forth in figure 1 to § 460.101 and table 1 to § 460.101. Table 1 to § 460.101—U.S. States and Territories per Climate Zone Zone 1 Zone 2 Zone 3 Alabama Arkansas Alaska American Samoa Arizona Colorado Florida California Connecticut Georgia Kansas Delaware Guam Kentucky District of Columbia Hawaii Missouri Idaho Louisiana New Mexico Illinois Mississippi North Carolina Indiana South Carolina Oklahoma Iowa Texas Tennessee Maine The Commonwealth of Puerto Rico Maryland U.S. Virgin Islands Massachusetts Michigan Minnesota Montana Nebraska Nevada New Hampshire New Jersey New York North Dakota Ohio Oregon Pennsylvania Rhode Island South Dakota Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming § 460.102 Building thermal envelope requirements. (a) Compliance options. (b) Prescriptive requirements. R- U- Table 1 to § 460.102 (b) Climate zone Exterior wall R- Exterior ceiling R- Exterior floor R- Window U- Skylight U- Door U- Glazed 1 13 22 22 1.08 0.75 0.40 0.7 2 13 22 19 0.5 0.55 0.40 0.6 3 19 22 22 0.35 0.55 0.40 Not applicable. Table 2 to § 460.102 (b) Climate zone Exterior wall R- Exterior ceiling R- Exterior floor R- Window U- Skylight U- Door U- Glazed 1 13 30 13 0.32 0.75 0.40 0.33 2 21 30 19 0.30 0.55 0.40 0.25 3 21 38 30 0.30 0.55 0.40 Not applicable. (2) For the purpose of compliance with the exterior ceiling insulation R- (3) A combination of R- R- R- (4) An individual skylight that has an SHGC that is less than or equal to 0.30 is not subject to the glazed fenestration SHGC requirements established in paragraph (b)(1) of this section. Adapted from section R402 of the 2021 IECC. (5) U- R- U- R- Table 3 to § 460.102 (b) U- R- Climate zone Exterior ceiling U- Exterior wall U- Exterior floor U- 1 0.061 0.094 0.049 2 0.061 0.094 0.056 3 0.061 0.068 0.049 Table 4 to § 460.102 (b) U Climate zone Exterior ceiling U- Exterior wall U- Exterior floor U- 1 0.043 0.094 0.078 2 0.043 0.063 0.056 3 0.037 0.063 0.032 (c) Performance requirements. U o Table 5 to § 460.102 (c) Climate zone Single-section U 1 0.110 2 0.091 3 0.074 Table 6 to § 460.102 (c) Climate zone Multi-section U 1 0.082 2 0.066 3 0.055 (2) Area-weighted average vertical fenestration U- (3) Area-weighted average skylight U- (4) Windows, skylights and doors containing more than 50 percent glazing by area must satisfy the SHGC requirements established in paragraph (b)(1) of this section on the basis of an area-weighted average. Adapted from section R402 of the 2021 IECC. (d) [Reserved]. (e) Determination of compliance with paragraph (c) of this section. U o U- (2) [Reserved] § 460.103 Installation of insulation. Insulating materials must be installed according to the insulation manufacturer's installation instructions and the requirements set forth in table 1 to 460.103, which is adapted from section R402 of the 2021 IECC. Table 1 to § 460.103—Installation of Insulation Component Installation requirements General Air-permeable insulation must not be used as a material to establish the air barrier. Access hatches, panels, and doors Access hatches, panels, and doors between conditioned space and unconditioned space, such as attics and crawlspaces, must be insulated to a level equivalent to the insulation of the surrounding surface, must provide access to all equipment that prevents damaging or compressing the insulation, and must provide a wood-framed or equivalent baffle or retainer when loose fill insulation is installed within an exterior ceiling assembly to retain the insulation both on the access hatch, panel, or door and within the building thermal envelope. Baffles For air-permeable insulations in vented attics, a baffle must be installed adjacent to soffit and eave vents. Baffles, when used in conjunction with eave venting, must be constructed using a solid material, maintain an opening equal or greater than the size of the vents, and extend over the top of the attic insulation. Ceiling or attic The insulation in any dropped ceiling or dropped soffit must be aligned with the air barrier. Narrow cavities Batts to be installed in narrow cavities must be cut to fit or narrow cavities must be filled with insulation that upon installation readily conforms to the available cavity space. Rim joists Rim joists must be insulated such that the insulation maintain permanent contact with the exterior rim board. Shower or tub adjacent to exterior wall Exterior walls adjacent to showers and tubs must be insulated. Walls Air permeable exterior building thermal envelope insulation for framed exterior walls must completely fill the cavity, including within stud bays caused by blocking lay flats or headers. § 460.104 Building thermal envelope air leakage. Manufactured homes must be sealed against air leakage at all joints, seams, and penetrations associated with the building thermal envelope in accordance with the component manufacturer's installation instructions and the requirements set forth in table 1 to 460.104. Sealing methods between dissimilar materials must allow for differential expansion, contraction and mechanical vibration, and must establish a continuous air barrier upon installation of all opaque components of the building thermal envelope. All gaps and penetrations in the exterior ceiling, exterior floor, and exterior walls, including ducts, flue shafts, plumbing, piping, electrical wiring, utility penetrations, bathroom and kitchen exhaust fans, recessed lighting fixtures adjacent to unconditioned space, and light tubes adjacent to unconditioned space, must be sealed with caulk, foam, gasket or other suitable material. The air barrier installation criteria are adapted from section R402 of the 2021 IECC. Table 1 to § 460.104—Air Barrier Installation Criteria Component Air barrier criteria Ceiling or attic The air barrier in any dropped ceiling or dropped soffit must be aligned with the insulation and any gaps in the air barrier must be sealed with caulk, foam, gasket, or other suitable material. Access hatches, panels, and doors, drop-down stairs, or knee wall doors to unconditioned attic spaces must be weather-stripped or equipped with a gasket to produce a continuous air barrier. Duct system register boots Duct system register boots that penetrate the building thermal envelope or the air barrier must be sealed to the subfloor, wall covering or ceiling penetrated by the boot, air barrier, or the interior finish materials with caulk, foam, gasket, or other suitable material. Electrical box or phone box on exterior walls The air barrier must be installed behind electrical and communication boxes or the air barrier must be sealed around the box penetration with caulk, foam, gasket, or other suitable material. Floors The air barrier must be installed at any exposed edge of insulation. The bottom board may serve as the air barrier. Mating line surfaces Mating line surfaces must be equipped with a continuous and durable gasket. Recessed lighting Recessed light fixtures installed in the building thermal envelope must be sealed to the drywall with caulk, foam, gasket, or other suitable material. Rim joists The air barrier must enclose the rim joists. The junctions of the rim board and the subfloor must be air sealed. Shower or tub adjacent to exterior wall The air barrier must separate showers and tubs from exterior walls. Walls The junction of the top plate and the exterior ceiling, and the junction of the bottom plate and the exterior floor, along exterior walls must be sealed with caulk, foam, gasket, or other suitable material. Windows, skylights, and exterior doors The rough openings around windows, exterior doors, and skylights must be sealed with caulk or foam. Subpart C—HVAC, Service Hot Water, and Equipment Sizing § 460.201 Duct system. Each manufactured home equipped with a duct system, which may include air handlers and filter boxes, must be sealed to limit total air leakage to less than or equal to four (4) cubic feet per minute per 100 square feet of conditioned floor area at a pressure differential of 0.1 inch w.g. (25 Pascals) across the system. Building framing cavities must not be used as ducts or plenums when directly connected to mechanical systems. The duct total air leakage requirements are adapted from section R403 of the 2021 IECC. § 460.202 Thermostats and controls. (a) At least one thermostat must be provided for each separate heating and cooling system installed by the manufacturer. The thermostat and controls requirements are adapted from section R403 of the 2021 IECC. (b) Any programmable thermostat installed by the manufacturer that controls the heating or cooling system must— (1) Be capable of controlling the heating and cooling system on a daily schedule to maintain different temperature set points at different times of the day and different days of the week; (2) Include the capability to set back or temporarily operate the system to maintain zone temperatures down to 55 °F (13 °C) or up to 85 °F (29 °C); and (3) Initially be programmed with a heating temperature set point no higher than 70 °F (21 °C) and a cooling temperature set point no lower than 78 °F (26 °C). (c) Heat pumps with supplementary electric-resistance heat must be provided with controls that, except during defrost, prevent supplemental heat operation when the heat pump compressor can meet the heating load. § 460.203 Service hot water. (a) Service hot water systems installed by the manufacturer must be installed according to the service hot water manufacturer's installation instructions. Where service hot water systems are installed by the manufacturer, the manufacturer must ensure that any maintenance instructions received from the service hot water system manufacturer are provided with the manufactured home. The service hot water requirements are adapted from section R403 of the 2021 IECC. (b) Any automatic and manual controls, temperature sensors, pumps associated with service hot water systems must provide access. (c) Heated water circulation systems must— (1) Be provided with a circulation pump; (2) Ensure that the system return pipe is a dedicated return pipe or a cold water supply pipe; (3) Not include any gravity or thermosyphon circulation systems; (4) Ensure that controls for circulating heated water circulation pumps start the pump based on the identification of a demand for hot water within the occupancy; and (5) Ensure that the controls automatically turn off the pump when the water in the circulation loop is at the desired temperature and when there is no demand for hot water. (d) All hot water pipes— (1) Outside conditioned space must be insulated to a minimum R- R- (2) From a service hot water system to a distribution manifold must be insulated to a minimum R- R- § 460.204 Mechanical ventilation fan efficacy. (a) Whole-house mechanical ventilation system fans must meet the minimum efficacy requirements set forth in table 1 to 460.204(a), except as provided in paragraph (b) of this section. The mechanical ventilation fan efficacy requirements are adapted from section R403 of the 2021 IECC. Table 1 to § 460.204 (a) Fan type description Airflow rate Minimum Heat recovery ventilator or energy recovery ventilator Any 1.2 In-line supply or exhaust fans Any 3.8 Other exhaust fan <90 2.8 Other exhaust fan ≥90 3.5 (b) Mechanical ventilation fans that are integral to heating, ventilating, and air conditioning equipment, including furnace fans as defined in § 430.2 of this subchapter, are not subject to the efficiency requirements in paragraph (a) of this section. § 460.205 Equipment sizing. Sizing of heating and cooling equipment installed by the manufacturer must be determined in accordance with ACCA Manual S (incorporated by reference; see § 460.3) based on building loads calculated in accordance with ACCA Manual J (incorporated by reference; see § 460.3). The equipment sizing criteria are adapted from section R403 of the 2021 IECC. Subpart D [Reserved]