When energy conservation codes were first introduced in the late 1970s, encouraging us to build more energy-efficient homes, three methods to meet the requirements were provided, each offering a different approach, but ending in the same destination: effective energy usage and greater energy conservation.

An increasing number of paths

The three original methods, or “compliance paths,” are still available in model codes today, though they have evolved, and additional paths have been added. The 2021 International Energy Conservation Code (IECC) provides a section applicable to residential buildings three stories above grade plane or less in height. These provisions are then reprinted in Chapter 11 of the 2021 International Residential Code (IRC).

There’s a lot to learn about the energy conservation codes, but the starting place is understanding the various paths to compliance and determining which is best for your project. The level of energy conservation required in the latest IRC has not been adopted in all areas of the country, so be sure to review your local codes when planning a project. (Here, I am speaking to the model code recommended to governments before any of their potential changes.)

Prescriptive vs. non-prescriptive paths

There are two significant categories that all code-­compliance paths fall under. The first is “prescriptive” design as outlined in the IRC, where a simple recipe for compliance is provided, such as the details for wood framing or concrete foundations. A structural design can also be provided by a third-party designer, architect, or engineer. This would be a “non-prescriptive path” to ­structural compliance.

These two options—prescriptive and non-prescriptive—are also found in the energy codes. Generally speaking, maximum assembly U-factors, found in section N1102.1.2, or insulation minimum R-values, found in section N1102.1.3, are the prescriptive options; the performance path and the Energy Rating Index (ERI) are the non-prescriptive options.