Task 34
Task 34
SHC Task 34

Testing of Building Energy Simulation Tools

Project (Task) Scope


This Task will investigate the availability and accuracy of building energy analysis tools and engineering models to evaluate the performance of innovative low-energy buildings. Innovative low-energy buildings attempt to be highly energy efficient through use of innovative energy-efficiency technologies or a combination of innovative energy efficiency and solar energy technologies. To be useful in a practical sense such tools must also be capable of modeling conventional buildings. The scope of the Task is limited to building energy simulation tools, including emerging modular type tools, and to widely used innovative low-energy design concepts. Activities will include development of analytical, comparative and empirical methods for evaluating, diagnosing, and correcting errors in building energy simulation software. (Image: IEA 34/43 Project Planning in Delft, Netherlands)

The audience for the results of the Task is building energy simulation tool developers, and codes and standards (normes) organizations that need methods for certifying software. However, tool users, such as architects, engineers, energy consultants, product manufacturers, and building owners and managers, are the ultimate beneficiaries of the research, and will be informed through targeted reports and articles.


The work for Task 34 is being performed in collaboration with IEA Energy Conservation in Building and Community Systems (ECBCS) Annex 43. For the purpose of defining the projects within SHC Task 34/ECBCS Annex 43 (IEA 34/43), it is useful to define the terms “comparative tests” and “empirical validation”. In comparative testing, an IEA Building Energy Simulation Test (BESTEST)-type comparative/diagnostic evaluation test procedure is written and software programs are compared to each other. Advantages of comparative tests include ease of testing many parameters, and that simple building descriptions may be used; the major disadvantage is lack of any truth standard in comparisons for cases where analytical solutions are not possible. In empirical validation, software is compared with carefully obtained experimental data. The advantage of empirical tests is that true validation of the models may be accomplished within the uncertainty of the experimental data; disadvantages are that gathering high quality experimental data is expensive and time consuming, making it difficult to test the individual effects of many parameters.

Proposed Comparative Tests include

  • BESTEST ground-coupled heat transfer with respect to floor slab constructions
  • BESTEST multi-zone heat transfer and shading
  • BESTEST air flow, including multi-zone air flow

Within the comparative test cases, analytical verification tests for evaluating basic heat transfer and mathematic processes in building energy analysis tools will be included where possible.

Proposed Empirical Validation tests include:

  • Shading/daylighting/load interaction
  • Chilled-water and hot-water mechanical systems and components
  • Buildings with double-skin facades.

When a number of building energy simulation programs are tested against the same empirical data set, comparative tests are also possible. Such comparative tests can help identify deficiencies in the empirical experiment if they exist, or broad-based deficiencies in the current modeling state of the art.

The following administrative support project will facilitate availability and distribution of IEA tool evaluation test procedures:

  • Develop a single web site that consolidates IEA tool evaluation tests from SHC Task 12 / ECBCS Annex 21, SHC Task 22, and SHC Task 34 / ECBCS Annex 43.