Window frame thermal performance simulation. Suitable methods according to climate and technology

Abstract

Within the framework of window labelling system elaboration in Argentina, this article questions the suitability of replicating calculation procedures from other countries with different climatic and technological contexts. This paper analyzes the methodological differences between existing standards for calculating window frame U-factor. It focuses on the impact of the radiation model applied on the frame outside boundary. Simulations were performed on different window frames under three sets of environmental conditions, first using the NFRC blackbody radiation model at the outside boundary, then using the ISO 15099 detailed radiation model. The comparison of the resulting U-factors shows significant differences (up to 12.7%) between both models. The impact of outside boundary radiation model choice increases with the non-planarity of outside frame boundary and decreases at high wind speeds. According to these results, the ISO 15099 detailed radiation model should be used on both sides of the frame, in order to maximise the accuracy of non-planar frames thermal transmittance calculation under any environmental conditions.

Heat Transfer Analysis of Timber Windows with Different Wood Species and Anatomical Direction

“…For instance, changes in window spacers and glazing greatly affect the overall performance of the window [18][19][20]. Besides, when the application ratio of wood is changed in designing windows, the shape of other design elements of the frame is inevitable, which also makes changes in heat flow [21]. Therefore, to prevent the possibility of misinterpretation due to these unintended variables, this study focused on the sensitivity analysis of individual windows according to the change of the set variables-wood species and anatomical direction-rather than the specific performance comparison according to the type of window.…”