The IEA has created a number of procedures for testing and validating building energy simulation programs. This work was the product of IEA Solar Heating and Cooling (SHC) Programme Task 22, and an earlier collaboration of IEA SHC Task 12 and Energy Conservation in Buildings and Community Systems (ECBCS) Annex 21.

These procedures are now being used by software developers to diagnose and correct errors in building energy simulation computer programs throughout the world. Some of these procedures have been, or are in the process of being, adopted by international codes and standards organizations for certification of software. ANSI/ASHRAE Standard 140 codified the original IEA Building Energy Simulation Test (BESTEST) as a standard method of test for software, and the European Committee for Standardization (CEN) used BESTEST to check their reference cooling load and cooling energy calculation methods based on the requirements of prEN 13791 and 13792.