The thermal performance of walls under actual service conditions: Evaluating the results of climatic chamber tests

• An experimental campaign tested four wall solutions in climatic chamber.
• The heat flows through different walls having the same U-value is evaluated and compared.
• Lightweight and heavyweight walls have very different behaviour under transient regime.
• Effects of thermal capacity should be considered in building energy optimization.
• Possible simplified parameters representing the dynamic behaviour of construction elements are evaluated.

The dynamic aspects of building envelope behaviour, which are usually evaluated using computer simulation tools that require substantial expertise for proper use, are receiving increasing amounts of attention. However, the U-value, which neglects the significance of heat capacity, continues to be the primary reference parameter for describing the thermal performance of walls in the building sector.The aim of this study is to highlight the importance of overcoming this widespread simplification by analysing, through climatic chamber tests, the actual performance of a set of walls that have equivalent U-values but are characterized by different heat capacities.