Appendix NG (RG) 2024 IECC Stretch Code

Compliance based on simulated building performance requires that a building comply with the following:

1. 1.

   The requirements of the sections indicated within Table N1105.2.

2. 2.

   The proposed total building thermal envelope thermal conductance, TC, shall be less than or equal to the building thermal envelope TC using the prescriptive U-factors and F-factors from Table N1102.1.2 multiplied by 1.08 in Climate Zones 0, 1 and 2, and 1.15 in Climate Zones 3 through 8 in accordance with Equation 11-1 and Section N1102.1.5. The area-weighted maximum fenestration SHGC permitted in Climate Zones 0 through 3 shall be 0.30.

3. 3.

   For each dwelling unit with one or more fuel-burning appliances for space heating, water heating, or both, the annual energy cost of the dwelling unit shall be less than or equal to 70 percent of the annual energy cost of the standard reference design. For all other dwelling units, the annual energy cost of the dwelling unit shall be less than or equal to 75 percent of the annual energy cost of the standard reference design. For each dwelling unit with greater than 5,000 square feet (465 m²) of living space located above grade plane, the annual energy cost of the dwelling unit shall be reduced by an additional 5 percent of annual energy cost of the standard reference design. Energy prices shall be taken from an approved source, such as the US Energy Information Administration’s state energy data system prices and expenditures reports. Code officials shall be permitted to require time-of-use pricing in energy cost calculations.

   Exceptions:

   1. 1.

      The energy use based on source energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost. The source energy multiplier for electricity shall be 2.51. The source energy multiplier for fuels other than electricity shall be 1.09.

   2. 2.

      The energy use based on site energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost.

Compliance based on an Energy Rating Index (ERI) analysis requires that the rated design and each confirmed as-built dwelling unit be shown to have an ERI less than or equal to the applicable value indicated in Table NG101.2 where compared to the ERI reference design as follows:

1. 1.

   Where on-site renewables are not installed, the maximum ENERGY RATING INDEX NOT INCLUDING OPP applies.

2. 2.

   Where on-site renewables are installed, the maximum ENERGY RATING INDEX INCLUDING OPP applies.

Residential buildings shall earn not less than 20 credits from not less than two measures specified in Table N1108.2. Five additional credits shall be earned for dwelling units with more than 5,000 square feet (465 m²) of living space located above grade plane. To earn credit as specified in Table N1108.2 for the applicable Climate Zone, each measure selected for compliance shall comply with the applicable subsections of Section N1108. Each dwelling unit or sleeping unit shall comply with the selected measure to earn credit. Interpolation of credits between measures shall not be permitted.