BESTEST (Building Energy Simulation TEST) is a method for testing, diagnosing, and validating the capabilities of building energy simulation programs. BESTEST test suites consist of analytical solutions and tests that allow a given building energy simulation program or design tool to be compared with the current state-of-the-art building energy modeling. The tests are sequenced with diagnostic logic so that the reasons for discrepancies can be quickly determined. Test suites include:

  • Basic building physics, including the building envelope and the building fabric
  • Tests emphasizing residential energy modeling issues, such as for software used with Home Energy Rating Systems (HERS)
  • Tests based on analytical solutions for a basic split system air conditioner
  • Comparative, realistic tests for a basic split system air conditioner
  • Tests for determining the multizone modeling capabilities of building energy simulation programs
  • Analytical, quasi-analytical, and comparative tests for determining the capabilities of building energy simulation programs to model the thermal coupling between the ground and a slab-on-grade floor.

View a listing of available test suites.

A number of the BESTEST test suites have been incorporated into ANSI/ASHRAE Standard 140-2011, "Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs," and are referenced by:

  • Internal Revenue Service 2008- 40: for evaluating commercial building energy efficiency tax credits;
  • ASHRAE Standard 90.1 (Energy Efficient Commercial and Non-Low Rise Resl Bldgs.)
  • ASHRAE Standard 189 (High Performance Green Building Design) Appendix D
  • IECC (International Energy Conservation Code)
  • IGCC (International Green Construction Code)
  • The newly developing COMNet User's Manual, which may also provide the basis for ASHRAE's proposed "Building Energy Quotient" building rating system
  • Numerous international citations (Europe, Japan, Australia/New Zealand, Canada, China etc.)
  • 2011 Florida Building Code.

BESTEST has also been adopted by RESNET for accrediting Home Energy Rating Systems (HERS) software.


exterior envelope simulation program capability tests, HVAC modeling tests, multizone modeling tests, ground coupling modeling tests, BESTEST, Standard 140


The overall method contains three validation processes:, comparative, analytical, and empirical. Empirical validation test suites are under development.

Expertise Required

Understanding of the underlying physics and the programs to be tested.


3000 (Standard 140 which is based on BESTEST, is the seventh most popular document out of 130 ASHRAE Standards and Guidelines)


Program developers and testers, software users.


Building thermal and physical characteristics as specified in the test case descriptions; weather data provided for download with download of User Manuals.


The program undergoing the test procedure must be at least capable of outputting annual heating and cooling loads.

Computer Platform

Any platform.

Programming Language



Reveals the strengths and weaknesses of a given software package in a methodical way.


Users may have to modify their code to perform BESTEST cases. This tends to occur for simplified software with many fixed assumptions.



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Available from NREL publications database