IECC Code Level Insulation

Scope

High Performance Insulation

 

Ceiling, wall, floor, and slab insulation levels shall comply with one of the following options:

1. Meet or exceed 2009 IECC levels OR
2. Achieve ≤ 133% of the total UA resulting from the U-factors in 2009 IECC Table 402.1.3, excluding fenestration and per guidance in note “d” below, AND home shall achieve ≤ 50% of the infiltration rate in Exhibit 1 of the National Program Requirements.

 

See the 2009 IECC insulation levels by climate zone interactive map

 

Read more about the ENERGY STAR National Program Requirements

 

 

Notes:

 

Insulation levels in a home shall meet or exceed the component insulation requirements in the 2009 IECC - Table 402.1.1. The following exceptions apply:

1. Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2009 IECC Table 402.2.5. In CZ 1 and 2, the continuous insulation requirements in this table shall be permitted to be reduced to R-3 for steel-frame wall assemblies with studs spaced at 24 inch on center. This exception shall not apply if the alternative calculations in "d" below are used;
2. For ceilings with attic spaces, R-30 shall satisfy the requirement for R-38 and R-38 shall satisfy the requirement for R-49 wherever the full height of uncompressed insulation at the lower R-value extends over the wall top plate at the eaves. This exemption shall not apply if the alternative calculations in "d" are used;
3. For ceilings without attic spaces, R-30 shall satisfy the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption shall be limited to 500 square feet or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in "d" are used;
4. An alternative equivalent U-factor or total UA calculation may also be used to demonstrate compliance, as follows:
   d.1.   An assembly with a U-factor equal or less than specified in 2009 IECC Table 402.1.3 complies.
   d.2    A total building thermal envelope UA that is less than or equal to the total UA resulting from the U-factors in Table 402.1.3 also complies. The insulation levels of all non-fenestration components (i.e., ceilings, walls, floors, and slabs) can be traded off using the UA approach under both the Prescriptive and the Performance Path. Note that fenestration products (i.e., windows, skylights, doors) shall not be included in this calculation. Also, note that while ceiling and slab insulation can be included in trade-off calculations, the R-value must meet or exceed the minimum values listed in Items 4.1 through 4.3 of the ENERGY STAR Checklist to provide an effective thermal break, regardless of the UA tradeoffs calculated. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The calculation for a steel-frame envelope assembly shall use the ASHRAE zone method or a method providing equivalent results, and not a series-parallel path calculation method.

 

Consistent with the 2009 IECC, slab edge insulation is only required for slab-on-grade floors with a floor surface less than 12 inches below grade. Slab insulation shall extend to the top of the slab to provide a complete thermal break. If the top edge of the insulation is installed between the exterior wall and the edge of the interior slab, it shall be permitted to be cut at a 45-degree angle away from the exterior wall.

 

Where an insulated wall separates a garage, patio, porch, or other unconditioned space from the conditioned space of the house, slab insulation shall also be installed at this interface to provide a thermal break between the conditioned and unconditioned slab. Where specific details cannot meet this requirement, partners shall provide the detail to ENERGY STAR to request an exemption prior to the home’s qualification. ENERGY STAR will compile exempted details and work with industry to develop feasible details for use in future revisions to the program. See a list of currently exempted details.

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Description

ENERGY STAR requires that ceiling, wall, floor, and slab insulation levels shall comply with one of the following options:

 

1. Meet or exceed 2009 IECC levels OR
2. Achieve ≤133% of the total UA resulting from the U-factors in 2009 IECC Table 402.1.3, excluding fenestration and per guidance in note “d” below, AND home shall achieve ≤ 50% of the infiltration rate in Exhibit 1 of the National Program Requirements.

 

This guide desctibes complying with both of these options.

 

Option A 

Option A is considered the prescriptive approach. Following Option A, insulation R-Values installed in the home must meet or exceed the values in the table below, which has been adapted from the 2009 IECC.

 

Table 1. Minimum Insulation Levels^a for New Homes as Required by the 2009 International Energy Conservation Code (IECC)

Click here for additional information about building energy codes. 

 

Exceptions to Option A

ENERGY STAR includes some exceptions to these requirements, as outlined below.  The exception for ceilings with attic spaces (from note b below) is included because the 2009 IECC assumes standard truss systems. The code allows a “credit” in the form of a reduced R-value requirement if insulation is allowed to be installed full height over the exterior wall plate line (e.g., raised heel truss). In ceilings without attic spaces (from note c below), the design of the roof/ceiling assembly does not allow sufficient space for the required insulation, so the code sets the requirements for those spaces at R-30 but limits the area to which this reduced R-value can apply to 500 ft² or 20% of the total insulated ceiling area, whichever is less. Specifically, the exceptions are as follows and match footnote 3 in the ENERGY STAR Qualified Homes Thermal Enclosure System Rater Checklist:

 

Additional Information Related to Option A

Slab edge insulation is allowed to be cut at a 45-degree bevel cut to avoid bringing the insulation to the top of the slab edge so a carpet tack strip can be attached. 

 

 

Option B

Option B is similar to Option A, but it uses U-factors instead of R-values and allows some tradeoffs among the envelope components. 

 

Calculating the Total Building Thermal Envelope UA (for Option B)

To use Option B for quality-installed insulation, the U-factor of each entire assembly (e.g., framed wall) must be equal to or less than the U-factor specified in Table 402.1.3 of the 2009 IECC (see Table 2 below). The entire assembly refers to framing, air films, insulation, etc., not just the insulation installed in the component as in Option A. Option B might be chosen instead of Option A if the home is using an innovative or less common construction technique such as log walls.

 

Table 2. Equivalent U-Factors^a Adapted from 2009 IECC Table 402.1.3

 

 

Option B requires the total building thermal envelope UA (U-factor x area) excluding the fenestration components (windows and doors) to be calculated, and that total UA must be less than or equal to 133% of the total UA resulting from the U-factors in Table 2 (also excluding fenestration). This option allows you to trade off some of the insulation for ceilings, walls, and foundation assemblies as long as you achieve 50% better infiltration than required per Exhibit 1 of the National Program Requirements.

 

The UA calculation must be done using a method consistent with the ASHRAE Handbook of Fundamentals and include the thermal bridging effects of framing materials (see below for different requirements for steel-frame assemblies). DOE’s REScheck software, meets these requirements and can be used to determine whether the home will achieve ≤ 133% of the total UA. To use REScheck for this purpose, follow these steps:

1. Select 2009 IECC from the Code menu.
2. Select the home’s location and enter the conditioned floor area on the Project screen.
3. Enter only ceiling, wall, and foundation components on the Envelope screen.  Do NOT enter windows or doors.
4. Review the REScheck compliance results.  As long as you are no more than 33% worse than code, you have met the first part of the requirement.

 

Steel-Frame Assemblies for Option B

The calculation for steel-frame envelope assemblies must use the ASHRAE zone method or a method providing equivalent results, and not a series-parallel path calculation method. There are online calculators to help with these methods.

 

 

Infiltration Rate Requirements for Option B

In order to use Option B, your envelope, exclusive of fenestration, must have a UA ≤ 133% of the total UA as described above AND meet the infiltration rates of the last column in Table 3.

 

Table 3. Infiltration Rates as Adapted from the ENERGY STAR National Program Requirements

 

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Ensuring Success

 

For Option A, it is important to consult the insulation requirements of the 2009 International Energy Conservation Code (IECC) to ensure the R-value requirements are met or exceeded. A table of these R-value requirements is provided in the description tab.  Be sure to review the exceptions that ENERGY STAR provides for ceilings (see the scope tab) as these can affect the required insulation levels.

 

Option B allows lower insulation values in the ceiling, walls, and foundation components if you improve infiltration rates. When calculating the total UA of the home, do NOT include doors and windows. Be sure to confirm that the home meets the improved infiltration rates provided in the table within the description tab.

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Climate

ENERGY STAR Version 3, (Rev. 6)

Thermal Enclosure Checklist, Quality-Installed Insulation. Meet or exceed 2009 IECC levels or Item 2.1.2. Insulation levels in a home shall meet or exceed the component insulation requirements in the 2009 IECC – Table 402.1.1. The following exceptions apply: a) Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2009 IECC – Table 402.2.5. In CZ 1 and 2, the continuous insulation requirements in this table shall be permitted to be reduced to R-3 for steel-frame wall assemblies with studs spaced at 24 in. on center. This exception shall not apply if the alternative calculations in d) are used; b) For ceilings with attic spaces, R-30 shall satisfy the requirement for R-38 and R-38 shall satisfy the requirement for R-49 wherever the full height of uncompressed insulation at the lower R-value extends over the wall top plate at the eaves. This exemption shall not apply if the alternative calculations in d) are used; c) For ceilings without attic spaces, R-30 shall satisfy the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption shall be limited to 500 sq. ft. or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in d) are used; d) An alternative equivalent U-factor or total UA calculation may also be used to demonstrate compliance, as follows: An assembly with a U-factor equal or less than specified in 2009 IECC Table 402.1.3 complies.

 

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Compliance

ENERGY STAR Version 3, (Rev. 6)

Thermal Enclosure Checklist, Quality-Installed Insulation. Meet or exceed 2009 IECC levels or Item 2.1.2. Insulation levels in a home shall meet or exceed the component insulation requirements in the 2009 IECC – Table 402.1.1. The following exceptions apply: a) Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2009 IECC – Table 402.2.5. In CZ 1 and 2, the continuous insulation requirements in this table shall be permitted to be reduced to R-3 for steel-frame wall assemblies with studs spaced at 24 in. on center. This exception shall not apply if the alternative calculations in d) are used; b) For ceilings with attic spaces, R-30 shall satisfy the requirement for R-38 and R-38 shall satisfy the requirement for R-49 wherever the full height of uncompressed insulation at the lower R-value extends over the wall top plate at the eaves. This exemption shall not apply if the alternative calculations in d) are used; c) For ceilings without attic spaces, R-30 shall satisfy the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption shall be limited to 500 sq. ft. or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in d) are used; d) An alternative equivalent U-factor or total UA calculation may also be used to demonstrate compliance, as follows: An assembly with a U-factor equal or less than specified in 2009 IECC Table 402.1.3 complies. A total building thermal envelope UA that is less than or equal to the total UA resulting from the U-factors in Table 402.1.3 also complies. The insulation levels of all non-fenestration components (i.e., ceilings, walls, floors, and slabs) can be traded off using the UA approach under both the Prescriptive and the Performance Path. Note that fenestration products (i.e., windows, skylights, doors) shall not be included in this calculation. Also, note that while ceiling and slab insulation can be included in trade-off calculations, Items 4.1 through 4.3 of the Checklist shall be met regardless of the UA tradeoffs calculated. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The calculation for a steel-frame envelope assembly shall use the ASHRAE zone method or a method providing equivalent results, and not a series-parallel path calculation method.

 

Consistent with the 2009 IECC, slab edge insulation is only required for slab-on-grade floors with a floor surface less than 12 inches below grade. Slab insulation shall extend to the top of the slab to provide a complete thermal break. If the top edge of the insulation is installed between the exterior wall and the edge of the interior slab, it shall be permitted to be cut at a 45-degree angle away from the exterior wall.

 

Where an insulated wall separates a garage, patio, porch, or other unconditioned space from the conditioned space of the house, slab insulation shall also be installed at this interface to provide a thermal break between the conditioned and unconditioned slab. Where specific details cannot meet this requirement, partners shall provide the detail to EPA to request an exception prior to the home’s qualification. EPA will compile exempted details and work with industry to develop feasible details for use in future revisions to the program. A list of currently exempted details is available through ENERGY STAR.

 

DOE Challenge Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3. Ceiling, wall, floor, and slab insulation shall meet or exceed 2012 IECC levels and achieve Grade 1 installation, per RESNET standards.

 

2009 IECC

Building thermal envelope components to meet or exceed the values in Table 402.1.1Insulation and Fenestration Requirements By Component. Section 402.2.1 Ceilings with attic spaces, R-30 satisfies the requirement for R-38 in the ceiling wherever insulation achieves its full height over the wall top plate at the eaves and is uncompressed. Similarly, R-38 can satisfy an R-49 wherever insulation achieves its full height over the wall top plate at the eaves and is uncompressed. Section 402.2.2 Ceilings without attic spaces, R-30 satisfies the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption is limited to 500 sq. ft. or 20% of the total insulated ceiling area, whichever is less. Section 402.2.8 Slab-on-grade floors, slabs less than 12 inches below grade to be insulated per Table 402.1.1 with insulation extending downward from top of the slab on inside or outside of the foundation wall. Below-grade insulation to extend the distance in Table 402.1.1. Insulation extending away from the building to be protected by pavement or at least 10 inches of soil. The top insulation edge may be cut at a 45-degree angle away from the exterior wall. Slab insulation isn’t required in areas of very heavy termite infestation, with approval of code official.*

 

2012 IECC

Building thermal envelope components to meet or exceed the values in Table R402.1.1Insulation and Fenestration Requirements By Component. Section R402.2.1 Ceilings with attic spaces, R-30 satisfies the requirement for R-38 in the ceiling wherever insulation achieves its full height over the wall top plate at the eaves and is uncompressed. Similarly, R-38 can satisfy an R-49 wherever insulation achieves its full height over the wall top plate at the eaves and is uncompressed. Section R402.2.2 Ceilings without attic spaces, R-30 satisfies the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption is limited to 500 sq. ft. or 20% of the total insulated ceiling area, whichever is less. Section R402.2.9 Slab-on-grade floors, slabs less than 12 inches below grade to be insulated per Table 402.1.1 with insulation extending downward from top of the slab on inside or outside of the foundation wall. Below-grade insulation to extend the distance in Table 402.1.1. Insulation extending away from the building to be protected by pavement or at least 10 inches of soil. The top insulation edge may be cut at a 45-degree angle away from the exterior wall. Slab insulation isn’t required in areas of very heavy termite infestation, with approval of code official.*

 

*Due to copyright restrictions, exact code text is not provided. For specific code text, refer to the applicable code.

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