The IECC 2009, 2012, & 2015: A Cross-Code Comparison of the Residential Energy Efficiency Sections

Here’s a general analysis of section R403 of the 2009, 2012, and 2015 IECC.

The International Code Council (ICC) continues to develop the International Energy Conservation Code (IECC) on a three-year cycle which has culminated in the latest version, the 2015 IECC. However, not every state is inclined to follow the same cycle when it comes to adoption of the IECC. Reasons for non-adoption vary, from perceived cost implications to lack of enforcement resources to complexity of changes. It is this last item, complexity of changes, upon which we will focus as the purpose of this multipart study.2012_IECC_Codes


The International Code Council (ICC) was founded in 1994 as a nonprofit member focused association with the express purpose of developing a single set of national model construction codes. Founding members came from the Building Officials and Code Administrators International, Inc. (BOCA), the International Conference of Building Officials (IBCO), and the Southern Building Code Congress International, Inc. (SBCCI).[1] The efforts of the three organizations culminated in the International Codes®, or I-Codes® starting in 2000 with a three-year cycle for revisions and updates.


This is a very general overview of the differences between the IECC 2009, 2012 and 2015 Residential Energy Efficiency section R403, along with a diagram that shows where sections have moved or new sections have been added. For further clarification, as well as more specific information as to the differences, please consult the following links:

In the description of the principal differences, we forgo using “IECC” as a prefix and just use the appropriate year to describe the version. Also, not all sections are listed if the text is the same across the board and to save diagram space. Please note that the “R” prefix has been used on some section numbers because that is what the IECC 2012 & 2015 now use and the analysis may be referencing a new section specifically.
Principal Differences in Section 403[2] [3]

403 (2009) — systems — was a section header for systems, became R403 for 2012 and is still R403 for 2015.

403.1 (2009) — mandatory controls — mentioned the requirement of a thermostat for each separate heating/cooling system across the board. Section became R403.1 for 2012 and is still R403.1 for 2015.

403.1.1 (2009) — programmable thermostats — outlined the thermostat programming requirements as well as when a thermostat was necessary. Section became R403.1.1 (2012) and was essentially the same but R403.1.1 (2015) eliminates the term forced air furnace which is replaced with primary heating or cooling system.

403.1.2 (2009) — heat pump supplementary heat — stated that a control must prevent operation of electric-resistance heat when the system can already meet the load. For R403.1.2 (2012), the text was relatively the same except for the addition of an allowance for electric resistance heat to operate during defrost for heat pumps. R403.1.2 (2015) is the same as 2012.

403.2 (2009) — ducts and air handlers — Section was just a header for both 2009 and 2012 with it being re-labeled as R403.2. It merely stated that products must comply with sections R403.2.1 through R

403.2.3. For R403.2 (2015), this section is completely divergent and uses the section number as a continuation of controls. It is now a new section pertaining to mandatory controls for hot-water boilers based on outdoor setback controls. The “old” R403.2 (2012) slips down in its entirety to R403.3 (2015).

403.2.1 (2009) — duct insulation for portions completely outside the thermal envelope — For 2009 & R403.2.1 (2012), the R-values were the same (supplies in the attic were at a minimum of R-8, everywhere else was R-6) and nothing was required for returns. However, for 2015, the section has been moved to R403.3.1 (2015) and now includes insulation for return ducts. Adjustments to the insulation levels are now allowed depending on the duct size. For ducts that are 3 inches in diameter or greater and in the attic, they must be a minimum of R-8, everywhere else is still R-6. For ducts that are smaller than 3 inches in diameter, the minimum insulation levels are R-6 for attics and R-4.2 for everywhere else.

403.2.2 (2009) — mandatory system sealing — This section as well as R403.2.2 (2012) addressed the sealing of ducts, air handlers, filter boxes and their appropriate tightness, which should be in compliance with the IMC. Also, a post-construction test or a rough-in test were not required if the air handler and all ducts are located within conditioned space. As for methods of duct sealing, R403.2.2 (2012) did allow exceptions for the use of air impermeable spray foam on joints, three screw connections, and special types of ducts that perform below a certain static pressure.

These concepts are still in the 2015, but have now been split into R403.3.2 (duct, air handler, and filter box sealing), R403.3.3 (duct pressure testing with report), and R403.3.4 (total duct leakage).

Note that the duct tightness requirement that was in R403.2.2 (2012) has been broken out for 2015 into two new sections with more explicit testing; those two new sections being R403.3.3 (2015) & R403.3.4 (2015).

R403.2.2.1 (2012) — air handler leakage — This section number, that didn’t exist for 2009, was newly introduced and had a restriction on the percentage of air leakage for air handlers. For 2015, the text is the same and shifts to section R403.3.2.1 (2015).

403.2.3 (2009) — building cavities — Building framing cavities were not to be used as supply ducts. R403.2.3 (2012) was changed to include the restriction for all ducts or plenums. For 2015, the text is the same and shifts to section R403.3.5 (2015).

403.3 (2009) — mechanical system piping insulation – Required the insulation of piping that carried fluids between a specific temperature range to a minimum of R-3. Concept was the same for R403.3 (2012). For 2015, the text is the same as for 2012 and shifts to section R403.4 (2015).

R403.3.1 (2012) – new section for mechanical system piping insulation that outlined the protection of piping insulation exposed to weather. For 2015, the text is the same and shifts to section 403.4.1.403.4 (2009) — circulating hot water systems — The basic concept was that piping was to be insulated to at least R-2 and that there was an automatic or readily accessible manual switch that could turn off the hot-water circulating pump when the system was not being used. R403.4 (2012) was given a new heading called “service hot water systems” along with an additional direction that energy conservation measures needed to be in accordance with new sections R403.4.1 (2012) and R403.4.2 (2012).

Note that Section 403.4 (2009) essentially was split for 2012 into section R403.4.1 (the automatic or readily accessible manual switch) and R403.4.2 (an upgrade to R-3 insulation and explicit directives as to its location).

R403.5 (2015) — service hot water systems (section title change) — For 2015, the main changes from R403.4 (2012) consisted of a heading number shift from R403.4 to R403.5 along with the addition of many new sections and refinements of shifted sections. In the context of comparing R403.4 (2012) to R403.5 (2015), they are essentially the same, but just reference different sections of the code.

R403.5.1 (2015) — This is a generic section that references which sections in the code water heated circulation systems and heat trace temperature maintenance systems need to comply. Accessibility to components is also mentioned. R403.5.1.1 (2015) is an expansion of requirements from R403.4.1 (2012) for heated water circulation systems. R403.5.1.2 (2015) is new and covers electric heat trace systems.R403.5.2 (2015) — This is a new section that pertains to water distribution systems that have one or more recirculation pumps and their required associated controls.

R403.5.3 (2015) — Is a change in piping insulation requirements from R403.4.2 (2012). Some items have actually been eliminated; specifically, the insulation of piping from the water heater to kitchen outlets and piping of specific run lengths.

R403.5.4 (2015) — This is a new section that pertains to drain water heat recovery units.

403.5 (2009) — mechanical ventilation — pertained mainly to gravity dampers for outdoor air intakes and exhaust. R403.5 (2012) tacked on ventilation requirements that met the IRC or IMC. For 2015, the only thing that changed was the section number, which is now R403.6.

R403.5.1 (2012) — was a new section that was added pertaining to mechanical ventilation system fans and their efficacy requirements and didn’t exist at all for 2009. For 2015, it now becomes section R403.6.1403.6 (2009) — equipment sizing — Initially, heating and cooling equipment had to be sized in accordance with section M1401.3 of the International Residential Code. For R403.6 (2012), sizing had to be done in accordance with ACCA Manual S and based on building loads calculated in accordance with ACCA Manual J or other approved methodology. For 2015, this section shifts to R403.7 and adds the requirement that new or replacement equipment has an efficiency rating greater or equal to the minimum required by federal law of the region where the project is located.

403.7 (2009) — system serving multiple dwelling units — This section required that the mechanical and water heating systems comply with the commercial sections of the code. R403.7 (2012) contained the same directive and just referenced the new re-numbered commercial energy code. For 2015, the text is exactly the same as for 2012 – only the section number has changed which is now R403.8.

403.8 (2009) & R403.8 (2012) — snowmelt system controls — This section required/requires outdoor temperature sensitive automatic controls. The only difference for 2015 is that the section number is now R403.9.

403.9 (2009) — pools — Directed compliance with specific subsections of the code, but for R403.9 (2012), the terminology of “in ground permanently installed spas” was added. This section title was also changed from “Pools” to “Pools and In ground Permanently Installed Spas”. For 2015, the section number is changed to R303.10 and the title is revised to “Pools and Permanent Spa Energy Consumption”.

403.9.1 (2009) & R403.9.1 (2012) — pool heaters — This section made sure that pool heaters essentially have an on-off switch override without having to adjust the thermostat. The section also prohibited continuously burning pilot lights for fuel fired heaters. For 2015, the section is now R403.10.2 and still maintains the same prohibition. However, the on-off switch must be in one of two specific locations and the operation of it shall not change thermostat settings.403.9.2 (2009) & R403.9.2 (2012) — time switches — The section was essentially the same between 2009 & 2012 (including exceptions) and pertained to the requirement for time switches that could automatically control heaters and pumps according to a preset schedule. For R403.9.2 (2012), there was the added caveat that equipment that had a built-in timer was to be considered in compliance. For 2015, the text remained the same from R403.9.2 (2012), but the section is now R403.10.3.

403.9.3 (2009) — pool covers — The section used to require an insulated vapor-retardant pool cover for pools heated to a specific temperature, except for pools that used over 60% alternative energy for heating. R403.9.3 (2012) ditched the requirement for insulation for the vapor-retardant pool cover and upped the ante for the exception to 70%. For 2015, this section is essentially the same except now it is labeled as R403.10.4.

R403.10.1 (2015) — This is a new section that pertains to a specific standard (APSP-145) with which pools and permanent spas must comply if they are considered an accessory to specific housing types.

R403.10 (2015) – See commentary under 403.9 (2009).

R403.11 (2015) — electric powered portable spas — This is a new section and directive for the energy consumption of electric powered portable spas which must be controlled per the requirements of the specific standard (APSP-14).

R403.12 (2015) — This is a new section that pertains to a specific standard (APSP-15) with which residential swimming pools and permanent spas must comply if they are considered an accessory to specific housing types.

The Market Effect and Relevance

Under the American Recovery and Reinvestment Act of 2009, the US Department of Energy agreed to provide funds to states that adopted the 2009 International Energy Conservation Code (IECC) or an equivalent for residential construction, contingent upon at least 90% compliance by 2017.[4] So far, we continue to see a mixed bag of IECC adoption across the country. Vermont and Maryland have already adopted the 2015, with others moving towards adoption in 2016. 10 states have adopted the 2012 and 24 states are still using the 2009. Believe it or not, there are 14 states that are either using an IECC code older than 2009 or they do not have a statewide energy code.[5]

Next Steps

We will continue to provide our analysis of the IECC 2009, 2012, & 2015 for the next industry report. For volume 3 of 2015, the analysis will continue with sections R 404, R405, & R406 which includes the energy rating index (ERI).





[4] (Reprinted from the CQIR 2013 Q3) 2009 IECC Requirements Of Most Immediate Concern To Manufacturers