Monday, February 2, 2015

What’s Changed in the IECC for 2015 – Part One

By Ryan VanArsdale

The International Energy Conservation Code (IECC) was established by the International Code Council to set the
minimum requirements for energy efficiency in design and construction. Each component of the building envelope (ceiling and wall insulation, window U-factor, solar heat gain coefficient (SHGC) and air infiltration) has minimum performance levels that must be met. Revised every three years, the IECC has kept pace with new technologies to increase energy efficiency in residential and commercial structures.  In the latest version, for 2015, the IECC has not only been updated as before, but has had a new section (R406 - The Energy Rating Index Compliance Alternative) added.


In order to help our clients stay up – to – date on current codes and regulations, NTA has compiled a list of some of the important differences between the 2012 and 2015 versions of the IECC. The most notable change to the new IECC is a new performance path that was approved, and is now Section R406, Energy Rating Index Compliance Alternative. This new option is based on an Energy Rating Index. This section lays out required ERI scores, building envelope levels and approved third party participation. 


  1. A significant change was made to the mechanical requirements by adding a provision for a combustion closet for structures in zones 3 – 8.
  2. Revised or added definitions:
    1. Continuous Insulation (ci)
    2. ERI Reference Design
    3. Fenestration
    4. Historic Building
    5. Insulated Siding
    6. Skylight
    7. Vertical Fenestration
  3. Two new sections have been added to Chapter 3, Section 301.4, Tropical Climate Zone, which defines what regions of the world are in a tropical climate, and the section for insulated siding, which must comply with ASTM C1363 to determine thermal resistance.
  4. In Chapter 4, a new exception was added to R402.2.4 for ‘Access Hatches and Doors’, dealing with vertical doors that provide access from conditioned to unconditioned spaces. Another exception was added to Section 402.2.7 regarding the amount of contact between the floor framing cavity insulation and the underside of the subfloor.
  5. A new section, R402.2.7, for ‘Walls with Partial Structural Sheathing’ was also added to Chapter 4.
  6. Other, existing parts of Chapter 4 were revised and updated:
    1. R402.3.2 'Glazed Fenestration SHGC'
    2. Table 402.4.1.1 'Air Barrier and Insulation Installation'
    3. Section 402.4.1.2 contains updated requirements for building envelope air leakage testing.
  7. Duct insulation provisions were revised to require both supply and return ducts in attics must be insulated to a minimum of R-8, where 3” or greater in diameter, and R-6 where less than 3” in diameter.  Supply and return ducts located elsewhere in the structure have also been revised.
  8. Service Hot Water Systems was updated in regards to gravity and thermos-syphon circulation systems, as well as re-circulation systems.
While this is not a complete listing of the changes that have been made to the 2015 IECC, or the requirements included, it gives you an idea of the level of changes that have been made. In our next blog, we will focus on Section R406, to help you prepare for the new ERI requirements.

For more help understanding and complying with the 2015 IECC, contact NTA. Our knowledgeable account managers and engineers can help you ensure your project is ready for the new 2015 IECC.

Read part two of this article here.

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