The International Energy Conservation Code 2009

Three groundbreaking changes to the residential requirements of the 2009 IECC include introducing specific performance criteria for envelope leakage, duct leakage, and lighting requirements into the residential code.

March 01, 2010
March/April 2010
A version of this article appears in the March/April 2010 issue of Home Energy Magazine.
Click here to read more articles about Codes and Standards

National energy codes got their start in 1975, when, in response to the oil embargo three years previous to that, Congress passed the Energy Policy and Conservation Act (EPCA). EPCA was amended most significantly in 1992 with the passage of the better-known Energy Policy Act (EPACT), which empowered the Department of Energy (DOE) to establish and regularly update a national requirement for energy-efficient residential and commercial buildings. The basis for the residential standard was the Model Energy Code (MEC), which at that time was jointly overseen by the three regional code development associations. (In 1994 the International Conference of Building Officials (ICBO), the Building Officials and Code Administrators (BOCA), and the Southern Building Code Congress International (SBCCI) merged to become a single national organization, the International Code Council (ICC). EPACT also charged DOE with determining if subsequent editions of the MEC would save energy, and if so establishing them as the new national code requirements. In 1998 the MEC was renamed the International Energy Conservation Code (IECC), and there have been subsequent editions in 2000, 2003, 2006, and 2009.

Highlights of 2009 IECC

There were three groundbreaking changes to the residential requirements of the 2009 IECC. Two of them are similarly structured; they introduce specific performance criteria for envelope leakage and duct leakage respectively. The third change introduces lighting requirements into the residential code.

Envelope leakage. Section 402.4.2 of 2009 IECC lists requirements for envelope leakage that include specifications for blower door testing. It sets a limit of 7 ACH50 for testing performed after rough-in and installation of all penetrations. This includes a list of test conditions that specifies that the duct system shall be included in the test (that is, supply and return registers shall not be sealed during the test). As an alternative to blower door testing, Section 402.4.2 lists 17 infiltration and insulation elements that must be visually inspected, together with the criteria for acceptance (see Table 402.4.2). Unfortunately, the code does not specify who may conduct blower door testing, so the door is left open for builders to perform their own tests. (This oversight is likely to be corrected in the 2012 edition.) The code does, however, specify that the building official may require that an independent third party, specifically not the insulation installer, conduct the visual inspection. Despite the visual inspection alternative, this change to the code’s air sealing requirements is significant in that it introduces a performance requirement for infiltration, instead of relying solely on a description of what must be sealed. The importance of this shift will not be lost on industry professionals whose careers depend on understanding the value of verified system performance. It should also be clear that this is likely to increase the demand for blower door testing in new construction, as at least some builders will opt for the blower door method of compliance.

Duct leakage. Section 403.2.2 of 2009 IECC introduces requirements for the performance testing of duct systems, but it too allows for a nonperformance alternative. After satisfying the basic prescriptive requirement to seal all ducts, there are three ways that builders may choose to comply with the performance testing requirement. They may pressure-test the system for leakiness, either at rough-in or on completion. Or they may design the system so that the ducts and air handlers are physically within conditioned space. If the system is tested on completion, the limit is 8 CFM25 leakage to the outdoors or 12 CFM25 total leakage per 100 square feet of conditioned floor area. In either case, the test must include the air handler. If the system is tested during rough-in, the limit is 6 CFM25 total leakage if the air handler has been installed, or 4 CFM25 if the air handler has not been installed. Once again, the code does not specify who may perform the leakage tests, so there is a potential for system installers to verify their own work. The third alternative—designing so that the ducts are within conditioned space—will perhaps be the most attractive choice for some builders since it avoids the potential difficulty of failing the performance tests. While this alternative does not guarantee leak-free systems (we know that interior spaces can communicate with outdoors), it is certainly a move in the right direction. And if the envelope air sealing requirements are met, then conditioned spaces should truly be indoors. This change in the code is likely to increase the demand for duct leakage testing by independent third parties, despite the weakness of the specific code language.

Lighting. The final major departure in 2009 IECC is a first-time requirement for efficient lighting in new homes. Section 404 specifies that at least 50% of the lamps in permanent fixtures must be “high-efficacy,” which is defined in ranges of light output (lumens) per energy input (watts). Lamps over 40 watts must provide at least 60 lumens per watt; lamps between 15 and 40 watts must provide at least 50 lumens per watt; and lamps under 15 watts must provide at least 40 lumens per watt. Generally speaking, this prohibits the use of traditional incandescent lamps in half of all fixtures but, unlike some state codes, it does not specify the locations of the permanent fixtures. As federal manufacturing requirements for lamp efficiency are set to take effect in 2012, it is likely that the percentage requirement for high-efficacy lamps will ratchet up to 75% or higher in the 2012 code.

There are several other important differences in the residential requirements between the 2006 and 2009 editions of the IECC. The most significant among them are:

  • Table 402.1.1 – Some increases in stringency to prescriptive envelope elements found in various locations (see Table 402.1.1):
  • decreased U-factor for glazing in Climate Zones 2, 3, and 4
  • decreased SHGC for glazing in Climate Zones 1, 2, and 3
  • increased wood framed wall R-value in Climate Zones 5 and 6
  • increased floor R-value in Climate Zone 8; and
  • increased basement wall R-value in Climate Zone 3, 6, 7, and 8.
  • 402.2.3 – Access hatches and doors. A new requirement has been added to this section, specifying that access doors and hatches from conditioned to unconditioned space must be insulated to the same R-value as their surrounding areas. The code had previously been silent on this detail, and therefore vague. This “change” simply clarifies what many understood to be the code’s intent all along. Also, since this section of the code is “Prescriptive” rather than “Mandatory,” lower R-value on these access openings can be overcome using the trade off methods specified in sections 402.1.3 and 402.1.4.
  • 403.1.1 – Programmable thermostat. Strangely, this new requirement applies only to primary heating systems of a “forced-air furnace,” and not to heat pumps, hydronic, or other systems. It requires at least one setback thermostats per dwelling unit, but does not call for independently controlled zones in multi-floor or larger homes. Criteria for set back ranges and scheduling are specified in detail.
  • 403.8 – Snowmelt system controls. This is another new requirement that introduces controls on snow- and ice-
  • melting systems. It requires automatic controls that can shut off operation when pavement reaches 50°F with no precipitation, plus automatic or manual control to shut off the system when outdoor air temperature exceeds 40°F.
  • 403.9.3 – Pool covers. Vapor retarder pool covers will be required on all heated pools (including whirlpools and spas), and if the water exceeds 90°F, then the cover must also have R-12 insulation.

2009 Coming to You

Many states are on a regular code update cycle, and it is almost inevitable that the 2009 IECC will take effect in these states. But this trend is likely to increase starting in 2010 because of federal policy. The American Recovery and Reinvestment Act of 2009 (ARRA, more commonly know as the Stimulus Bill) requires that states taking its stimulus funding adopt the 2009 IECC (or its efficiency equivalent) for residential buildings, and also develop a plan that will result in 90% compliance within eight years. DOE indicates that all 50 states, the District of Columbia, Puerto Rico, Guam, and other territories have accepted ARRA funds, so they should be committed to the 2009 IECC as their new energy code. The current status of energy code adoptions is depicted in a map, developed by the Building Codes Assistance Project (see p. 22). Many of these locales will be using a portion of their funding to provide code training and technical support beginning in 2010, so be on the look out for those opportunities.

Looking Ahead to the 2012 IECC

Although the final content of the 2012 IECC will not be determined until late in 2010, readers might be interested in some of the possible changes that are currently under consideration. There were many proposals in the most recent code change cycle, and of the 250 submissions, 153 deal with the administrative and technical requirements for low-rise residential buildings. The majority of these proposals focus on specific sections of the code, but a handful offer comprehensive overhauls of the 2009 IECC. Among these, proposal EC13, submitted by the DOE, was approved by the Code Committee as submitted, and characterizes what might be included in the 2012 code. Covering this proposal in detail would be an article on its own, but some of the major changes can be highlighted.

The DOE proposal seeks a 30% increase in stringency in the 2012 IECC compared to the 2006 IECC. In order to achieve this, DOE recommends a mix of increased stringencies and proposes whole new areas that have not been addressed in the codes before, such as recognizing the relationship between hot water pipe length and efficiency. The proposal also seeks to clarify administrative elements that have been confusing for users, like the distinctions between “Mandatory” and “Prescriptive” requirements.

The prescriptive envelope requirements are contained in Table 402.1.1 with proposed deletions shown in strikethrough and additions in underline (see “For more information:” below for the complete monograph of the proposed changes). Window/door and skylight U-factors would be reduced generally with the exception of the very warmest Climate Zone where the modest 1.20 requirement has been removed. Ceiling R-values would be increased in Climate Zones 3 and 5, and 4 Marine, and wall R-values would be increased in Climate Zones 4, 6, 7, and 8. (The “Equivalent U-Factor” Table 402.1.3 would be changed to match the prescriptive table, and the steel framing conversion table, 402.2.5, would be modified to include the new prescriptive elements.)

David Weitz is director of the Applied Building Science Division of Conservation Services Group, headquartered in Westborough, Massachusetts. The Division develops standards, protocols, and quality assurance procedures for CSG, which over the past 25 years has performed energy evaluations and improvements in over one million homes throughout the United States. Before coming to CSG, David was executive director of the Building Codes Assistance Project; Energy Code Coordinator for the Commonwealth of Massachusetts; and he has served three terms as a member of the IECC development committee.

For more information:

Details on the code development process, including all forms and procedures for submitting proposed changes, can be found on the ICC Web site at

A comprehensive comparison of changes between the 2006 and 2009 IECC was developed by the Britt/Makela Group, and is available at

The complete monograph of proposed changes for the IECC is available on the ICC Web site at EC 13 begins on page 67 of that document.

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