87 FR 32818, May 31, 2022, unless otherwise noted.
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 July 1, 2025.
[88 FR 34419, May 30, 2023]
Adapted from section R202 of the 2021 IECC and as used in this part—
2021 IECC means the 2021 version of the International Energy Conservation Code, issued by the International Code Council.
Access (to) means that which enables a device, appliance or equipment to be reached by ready access or by a means that first requires the removal or movement of a panel or similar obstruction.
Air barrier means one or more materials joined together in a continuous manner to restrict or prevent the passage of air through the building thermal envelope and its assemblies.
Automatic means self-acting or operating by its own mechanism when actuated by some impersonal influence.
Building thermal envelope means exterior walls, exterior floors, exterior ceiling, or roofs, and any other building element assemblies that enclose conditioned space or provide a boundary between conditioned space and unconditioned space.
Ceiling means an assembly that supports and forms the overhead interior surface of a building or room that covers its upper limit and is horizontal or tilted at an angle less than 60 degrees (1.05 rad) from horizontal.
Climate zone means a geographical region identified in § 460.101.
Conditioned space means an area, room, or space that is enclosed within the building thermal envelope and that is directly or indirectly heated or cooled. Spaces are indirectly heated or cooled where they communicate through openings with conditioned space, where they are separated from conditioned spaces by uninsulated walls, floors or ceilings, or where they contain uninsulated ducts, piping, or other sources of heating or cooling.
Continuous air barrier means a combination of materials and assemblies that restrict or prevent the passage of air from conditioned space to unconditioned space.
Door means an operable barrier used to block or allow access to an entrance of a manufactured home.
Dropped ceiling means a secondary nonstructural ceiling, hung below the exterior ceiling.
Dropped soffit means a secondary nonstructural ceiling that is hung below the exterior ceiling and that covers only a portion of the ceiling.
Duct means a tube or conduit, except an air passage within a self-contained system, utilized for conveying air to or from heating, cooling, or ventilating equipment.
Duct system means a continuous passageway for the transmission of air that, in addition to ducts, includes duct fittings, dampers, plenums, fans, and accessory air-handling equipment and appliances.
Eave means the edge of the roof that overhangs the face of an exterior wall and normally projects beyond the side of the manufactured home.
Equipment includes material, devices, fixtures, fittings, or accessories both in the construction of, and in the plumbing, heating, cooling, and electrical systems of a manufactured home.
Exterior ceiling means a ceiling that separates conditioned space from unconditioned space.
Exterior floor means a floor that separates conditioned space from unconditioned space.
Exterior wall means a wall, including a skylight well, that separates conditioned space from unconditioned space.
Fenestration means vertical fenestration and skylights.
Floor means a horizontal assembly that supports and forms the lower interior surface of a building or room upon which occupants can walk.
Glazed or glazing means an infill material, including glass, plastic, or other transparent or translucent material used in fenestration.
Heated water circulation system means a water distribution system in which one or more pumps are operated in the service hot water piping to circulate heated water from the water heating equipment to fixtures and back to the water heating equipment.
Insulation means material deemed to be insulation under 16 CFR 460.2.
Manual means capable of being operated by personal intervention.
Manufactured home means a structure, transportable in one or more sections, which in the traveling mode is 8 body feet or more in width or 40 body feet or more in length or which when erected onsite is 320 or more square feet, and which is built on a permanent chassis and designed to be used as a dwelling with or without a permanent foundation when connected to the required utilities, and includes the plumbing, heating, air conditioning, and electrical systems contained in the structure. This term includes all structures that meet the above requirements except the size requirements and with respect to which the manufacturer voluntarily files a certification pursuant to 24 CFR 3282.13 and complies with the construction and safety standards set forth in 24 CFR part 3280. The term does not include any self-propelled recreational vehicle. Calculations used to determine the number of square feet in a structure will be based on the structure's exterior dimensions, measured at the largest horizontal projections when erected on site. These dimensions will include all expandable rooms, cabinets, and other projections containing interior space, but do not include bay windows. Nothing in this definition should be interpreted to mean that a manufactured home necessarily meets the requirements of the U.S. Department of Housing and Urban Development Minimum Property Standards (HUD Handbook 4900.1) or that it is automatically eligible for financing under 12 U.S.C. 1709(b).
Manufacturer means any person engaged in the factory construction or assembly of a manufactured home, including any person engaged in importing manufactured homes for resale.
Opaque door means a door that is not less than 50 percent opaque in surface area.
R-value (thermal resistance) means the inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other surface for a unit temperature difference between the two surfaces, under steady state conditions, per unit area (h × ft2 × °F/Btu).
Rough opening means an opening in the exterior wall or roof, sized for installation of fenestration.
Service hot water means supply of hot water for purposes other than comfort heating.
Skylight means glass or other transparent or translucent glazing material, including framing materials, installed at an angle less than 60 degrees (1.05 rad) from horizontal, including unit skylights, tubular daylighting devices, and glazing materials in solariums, sunrooms, roofs and sloped walls.
Skylight well means the exterior walls underneath a skylight that extend from the interior finished surface of the exterior ceiling to the exterior surface of the location to which the skylight is attached.
Solar heat gain coefficient (SHGC) means the ratio of the solar heat gain entering a space through a fenestration assembly to the incident solar radiation. Solar heat gain includes directly transmitted solar heat and absorbed solar radiation that is then reradiated, conducted, or convected into the space.
State means each of the 50 states, the District of Columbia, the Commonwealth of Puerto Rico, Guam, the U.S. Virgin Islands, and American Samoa.
Thermostat means an automatic control device used to maintain temperature at a fixed or adjustable set point.
U-factor (thermal transmittance) means the coefficient of heat transmission (air to air) through a building component or assembly, equal to the time rate of heat flow per unit area and unit temperature difference between the warm side and cold side air films (Btu/h × ft2 × °F).
Uo (overall thermal transmittance) means the coefficient of heat transmission (air to air) through the building thermal envelope, equal to the time rate of heat flow per unit area and unit temperature difference between the warm side and cold side air films (Btu/h × ft2 × °F).
Ventilation means the natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, any space.
Vertical fenestration means windows (fixed or moveable), opaque doors, glazed doors, glazed block and combination opaque and glazed doors composed of glass or other transparent or translucent glazing materials and installed at a slope of greater than or equal to 60 degrees (1.05 rad) from horizontal.
Wall means an assembly that is vertical or tilted at an angle equal to greater than 60 degrees (1.05 rad) from horizontal that encloses or divides an area of a building or room.
Whole-house mechanical ventilation system means an exhaust system, supply system, or combination thereof that is designed to mechanically exchange indoor air with outdoor air when operating continuously or through a programmed intermittent schedule to satisfy the whole house ventilation rates.
Window means glass or other transparent or translucent glazing material, including framing materials, installed at an angle greater than 60 degrees (1.05 rad) from horizontal.
Zone means a space or group of spaces within a manufactured home with heating or cooling requirements that are sufficiently similar so that desired conditions can be maintained using a single controlling device.
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 and the material must be available to the public. All approved material is available for inspection at DOE and at the National Archives and Records Administration (NARA). Contact DOE at: The U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Program, Sixth Floor, 950 L'Enfant Plaza SW, Washington, DC 20024, (202) 586-9127, Buildings@ee.doe.gov, https://www.energy.gov/eere/buildings/building-technologies-office. For information on the availability of this material at NARA, email: fr.inspection@nara.gov, or go to: www.archives.gov/federal-register/cfr/ibr-locations.html. The material may be obtained from the following sources:
(a) ACCA. Air Conditioning Contractors of America, Inc., 2800 S. Shirlington Road, Suite 300, Arlington, VA 22206, 703-575-4477; 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, 11491 Sunset Hills Road, Reston, VA 20190-5254; 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); IBR approved for § 460.102(e).
(2) [Reserved].
(a) General. A manufactured home must comply with the energy conservation standards specified for the applicable tier as presented in paragraphs (b) and (c) of this section.
(b) Tier 1. A single-section manufactured home (i.e., a Tier 1 manufactured home) must comply with all applicable requirements in subparts B and C of this part.
(c) Tier 2. A multi-section manufactured home (i.e., a Tier 2 manufactured home) must comply with all applicable requirements in subparts B and C of this part.
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.
| 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 |
(a) Compliance options. The building thermal envelope must meet either the prescriptive requirements of paragraph (b) of this section or the performance requirements of paragraph (c) of this section.
(b) Prescriptive requirements.
(1) The building thermal envelope must meet the applicable minimum R-value (nominal value of insulation), and the glazing maximum U-factor and SHGC, requirements set forth in table 1 to § 460.102(b)(1) and table 2 to § 460.102(b)(2) or component U-values set forth in table 3 to § 460.102(b)(5) and table 4 to § 460.102(b)(5).
| Climate zone | Exterior wall insulation R-value |
Exterior ceiling insulation R-value |
Exterior floor insulation R-value |
Window U-factor |
Skylight U-factor |
Door U-factor |
Glazed fenestration SHGC |
|---|---|---|---|---|---|---|---|
| 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. |
| Climate zone | Exterior wall insulation R-value |
Exterior ceiling insulation R-value |
Exterior floor insulation R-value |
Window U-factor |
Skylight U-factor |
Door U-factor |
Glazed fenestration SHGC |
|---|---|---|---|---|---|---|---|
| 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-value requirement of paragraph (b)(1) of this section, the truss heel height must be a minimum of 5.5 inches at the outside face of each exterior wall.
(3) A combination of R-21 batt insulation and R-14 blanket insulation may be used for the purpose of compliance with the floor insulation R-value requirement of table 2 to § 460.102(b)(1), Climate Zone 3.
(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- factor alternatives to R-value requirements. Compliance with the applicable requirements in paragraph (b)(1) of this section may be determined using the applicable maximum U-factor values set forth in table 3 to § 460.102(b)(5) and table 4 to § 460.102(b)(5), which reflect the thermal transmittance of the component, excluding fenestration, and not just the insulation of that component, as an alternative to the minimum nominal R-value requirements set forth in table 1 to § 460.102(b)(1) and table 2 to § 460.102(b)(1), respectively.
| Climate zone | Exterior ceiling U-factor |
Exterior wall U-factor |
Exterior floor U-factor |
|---|---|---|---|
| 1 | 0.061 | 0.094 | 0.049 |
| 2 | 0.061 | 0.094 | 0.056 |
| 3 | 0.061 | 0.068 | 0.049 |
| Climate zone | Exterior ceiling U-factor |
Exterior wall U-factor |
Exterior floor U-factor |
|---|---|---|---|
| 1 | 0.043 | 0.094 | 0.078 |
| 2 | 0.043 | 0.063 | 0.056 |
| 3 | 0.037 | 0.063 | 0.032 |
(c) Performance requirements.
(1) The building thermal envelope must have a Uo that is less than or equal to the applicable value specified in table 5 to § 460.102(c)(1) and table 6 to § 460.102(c)(1).
| Climate zone | Single-section Uo |
|---|---|
| 1 | 0.110 |
| 2 | 0.091 |
| 3 | 0.074 |
| Climate zone | Multi-section Uo |
|---|---|
| 1 | 0.082 |
| 2 | 0.066 |
| 3 | 0.055 |
(2) Area-weighted average vertical fenestration U-factor must not exceed 0.48 in Climate Zone 2 or 0.40 in Climate Zone 3. Adapted from section R402 of the 2021 IECC.
(3) Area-weighted average skylight U-factor must not exceed 0.75 in Climate Zone 2 and Climate Zone 3. Adapted from section R402 of the 2021 IECC.
(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.
(1) Uo must be determined in accordance with Overall U-Values and Heating/Cooling Loads—Manufactured Homes (incorporated by reference; see § 460.3)
(2) [Reserved]
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.
| 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. |
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.
| 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. |
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.
(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.
(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-value of R-3; and
(2) From a service hot water system to a distribution manifold must be insulated to a minimum R-value of R-3.
(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.
| Fan type description | Airflow rate minimum (cfm) |
Minimum efficacy (cfm/watt) |
|---|---|---|
| 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.
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.