Diagnosing Total UA Code Compliance differences

Note: This article focuses on code compliance differences between Ekotrope CodeCheck and other Software Tools available for Total UA (IECC Prescriptive Path) calculations. For tips on diagnosing code compliance differences between Ekotrope RATER (HERS, ENERGY STAR, DOE Efficient New Homes, or IECC Performance/ERI Paths), check out this article. Both the Ekotrope RATER and CodeCheck use the same algorithm for Total UA calculation.

When transitioning to Ekotrope CodeCheck, users might encounter differences between the compliance results generated by other software tools (e.g., RESCheck).  They may also find building designs that meet the Total UA path in other software tools but do not meet it in Ekotrope CodeCheck.

These differences can be caused by any of the following three items:

1. Differences in input parameters between Ekotrope CodeCheck and the other software due to the user error.

2. Differences in the Total UA calculations of Ekotrope CodeCheck and the other software.

3. Differences between software interpretations of the code language, or bugs in the implementation.

Here are some steps and guidance for diagnosing the issue and minimizing the differences:

1. Compare the UA compliance report to see where the major differences are (e.g., Ceiling, Above-Grade Walls, Fenestration, Slabs, Basement, etc.). This report is called "IECC UA Compliance".  This report provides the breakdown of the UA calculation for each component of the building. Compare a similar report from the other software, noting down the differences between the two. Often there will be an extra envelope/fenestration area, incorrect R-values, etc. in one of the input files.

2. Compare the full input reports. In Ekotrope, print the "Building Summary". These reports contain most of the user inputs with effective R-values for each modeled component. The "Building Summary" report in the "Miscellaneous" category will show the as-modeled user inputs. The "Reference Home Summary" report in the "IECC" or "State Amended Codes" category will show the respective reference R-values and area inputs as per the code compliance. Compare these reports between the as-modeled and reference home to double-check on the R-value and area inputs. Compare the differences with the other software, which will help diagnose the issue.

In any case, if you notice any major differences in the reference home implementation, please reach out to us at support@ekotrope.com for further help.