Standard 140 specifies a method of test for evaluating the technical capabilities and applicability of software used in calculating the thermal performance of buildings and their HVAC systems. These test procedures can be used to identify and diagnose predictive differences from building performance simulation software that may be caused by algorithmic differences, modeling limitations, faulty coding, inadequate documentation, or input errors; the procedures can also be used to evaluate the acceptability of software.

The current set of tests focuses on building thermal envelope and fabric loads and HVAC equipment performance, and includes:
* Comparative tests, in which a program's results may be compared to a different version of itself or to the results of other programs;
* Analytical verification tests, in which a program's results may be compared to analytical, quasi-analytical, or verified numerical model solutions.

This procedure tests software over a broad range of parametric interactions and for a number of different output types, thus minimizing the concealment of algorithmic differences by compensating errors. Different building performance simulation programs, representing different degrees of modeling complexity, can be tested. However, some of the tests may be incompatible with some building performance simulation programs.

The revised 2023 edition of Standard 140 includes all the test cases of Standard 140-2020 and adds a new test suite that evaluates a software's ability to read and interpret standard format weather data. The 2023 edition also introduces acceptance criteria consisting of quantified acceptable results ranges for selected test cases; these criteria enhance previous qualitative guidance for comparing tested software results with other software and analytical verification results. In addition, the standard was reorganized to facilitate citing current test suites and adding future test suites. The 2023 edition includes online access to electronic supporting files. The following software may be required to view some files: Microsoft Windows; Microsoft Word; Microsoft Excel; Microsoft Notepad; and Adobe Reader or Adobe Acrobat.