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The influence of "cold bridges" on the reduced heat transfer resistance of wall enclosures, which characterizes their thermal insulation properties and energy efficiency, was studied. A nine-story monolithic frame residential building in the city of Lviv was considered. Wall enclosing structures 250 mm thick made of hollow ceramic blocks on a cement-sand mortar. The thermal insulation of the walls is made by the wet method with plates made of mineral wool 100 mm thick. Windows and transparent facade systems made of PVC profiles filled with double-glazed windows. The following heat-conducting inclusions were considered: mineral wool fastening dowels, window slopes, inter-floor and balcony ceilings, columns, corner joints. To determine the reduced heat transfer resistance, modeling of wall nodes was performed using the finite element method using the Agros2D software complex. As a result of the calculations, the temperature fields and heat flows for the corresponding nodes with "cold bridges" were obtained. Based on calculations of two-dimensional temperature fields of wall fragments, linear heat transfer coefficients for linear heat-conducting inclusions were calculated. The reduced heat transfer resistance for the external walls of the building in question was determined, taking into account the named "cold bridges". The results indicate a significant influence of these heat-conducting inclusions. The influence of each heat-conducting inclusion on the heat transfer coefficient was evaluated. It is concluded that heat transfer inclusions such as ceilings have the greatest impact on heat transfer for the house under study. The results of the research will be useful in the analysis of energy efficiency and the design of multi-story residential buildings with a monolithic frame.
Bodnar et al. (Fri,) studied this question.