IEA-SHC Task 34/ECBCS Annex 43

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Testing and Validation of Building Energy Simulation Tools

Contact: V.Lemort, P.André


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.

The recently issued Energy Performance Directive (EPD) of the European Union emphasizes performance-based standards and requires certification of software used to show compliance with energy performance standards (normes). This is a very positive development because with true performance-based normes, renewable energy technologies and innovative energy efficiency measures in buildings are encouraged and not constrained by prescriptive requirements. However, the modeling of innovative low energy buildings is challenging, and existing methods for testing such software are not yet comprehensive enough. In this context the work proposed for this task may be thought of as “pre-normative” research. For example, at the April 2003 Task Definition Workshop in Delft, Netherlands, participants established that the reference calculation methods under development by CEN will work for the vast majority of conventional buildings, but will not be adequate for innovative low energy buildings. Therefore, the work proposed under this Task is meant to ensure that the software for modeling innovative low energy buildings can be tested, validated, and certified in accordance with the needs of those organizations responsible for promulgating and enforcing building codes and standards.

Experimental set-up for water cooling coil and air cooled chiller (Energy Resource Station, Iowa, USA)


The goal of this Task is to undertake pre-normative research to develop a comprehensive and integrated suite of building energy analysis tool tests involving analytical, comparative, and empirical methods. These methods will provide for quality assurance of software, and some of the methods will be enacted by codes and standards bodies to certify software used for showing compliance to building energy standards. This goal will be pursued by accomplishing the following objectives:

  • Create and make widely available a comprehensive and integrated suite of IEA Building Energy Simulation Test (BESTEST) cases for evaluating, diagnosing, and correcting building energy simulation software. Tests will address modeling of the building thermal fabric and building mechanical equipment systems in the context of solar and low energy buildings.
  • Maintain and expand as appropriate analytical solutions for building energy analysis tool evaluation.
  • Create and make widely available high quality empirical validation data sets, including detailed and unambiguous documentation of the input data required for validating software, for a selected number of representative design conditions.


Comparative and empirical validation of a water cooling coil model by means of experimental measurements


 IEA website

ECBCS Program website

IEA SHC Task 34 / ECBCS Annex43 website

Activities in Belgium

L’objectif prioritaire de ce projet est de finaliser la mise au point des outils de simulation énergétique des bâtiments et de leurs équipements actuellement utilisés à l’ULg (EES et TRNSYS) ainsi que la fourniture de solutions de référence, validées grâce aux procédures et aux données issues du projet IEA 34/43.

Ce projet porte bien en effet sur le développement de telles procédures (dans la continuation de travaux qui ont débuté il y a une bonne quinzaine d’années et qui ont déjà débouché sur des procédures standardisées acceptées tant au niveau de l’ASHRAE que du CEN) en s’appuyant sur des données expérimentales de haute qualité et sur des comparaisons entre modèles et sur des solutions analytiques de référence.

L’effort porte encore actuellement sur une série de problèmes spécifiques (correspondant à autant de sous-tâches), dont trois sont particulièrement pertinents par rapport aux besoins de la Région Wallonne :

-         La vérification  des modèles de bâtiments multi-zones, y compris le problèmes des couplages par mouvements d’air ;

-         La validation des calculs d’interactions entre vitrages, éclairages et charges thermiques ;

-         La vérification des modèles des composants et systèmes HVAC.

Les travaux réalisés précédemment par l’ULg portaient effectivement sur ces trois sous-tâches et sur leur valorisation au travers des outils de calculs pratiques. Les programmes de simulation et les modèles sous-jacents qui ont été mis au point permettent déjà d’établir des solutions de référence, pouvant servir à différents usages, notamment :

-         La validation des méthodes simplifiées de calculs  de la performance énergétique des bâtiments ;

-    La vérification, a priori ou in situ, de la performance énergétique de bâtiments (dans le cadre de son commissionnement), en conformité avec la Directive Européenne.

Model Data Bank

A model data bank was set up with models developed under IEA annex 43.  The model web page is accessible on this link.



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