Abstract:In the design of high-energy performance buildings with ventilated facade systems, the evaluation of point thermal bridges is complicated and is often ignored in practice. This paper analyzes the relationship between the point thermal bridges resulting from aluminum fasteners, which are used for installation facades cladding, and the thermal properties of materials that are used in external walls layers and dimension of layers. Research has shown that the influence of the point thermal bridges on the U-value of the entire wall may achieve an average of up to 30% regarding thermal properties of materials of the external wall layers and the dimension of layers. With the increase in thermal conductivity of the bearing layer material and the thickness of the thermal insulation layer, the point thermal transmittance χ-value increased. For this reason, the U-value of the entire wall may increase by up to 35%. With the increase of the thickness of the bearing layer and thermal conductivity value of thermal insulation layer, the point thermal transmittance χ-value decreased by up to 28%. A simplified methodology is presented for the evaluation of point thermal bridges based on the thermal and geometrical properties of external wall layers.

This paper provides initial results from experimental work on the durability of external thermal insulation composite system (ETICS). In order to predict service life of ETICS, the accelerated climatic cycle was composed on the basis of earlier scientific research and the statistic data of the Lithuanian climate. The research aims to assess the durability and service life of finishing coat by calculating the amount of moisture while measuring the 24 h water absorption of the samples during water absorption and drying testing either by measuring the changes of bond strength. The offered accelerated weathering cycle could be useful for ETICS manufacturers and it could be used for testing and proof of highly frost-resistant products.

DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3834

The aim of the research was to evaluate an influence of floating floor construction specimen size on weighted reduction in impact sound pressure level ΔL_W. The large size (area ≥ 10 m²) specimens should be used according to LST EN ISO 10140 series standards. The problem is that produce large specimens is expensive and time-consuming process. So more rapid and cheaper way is to use smaller size (area < 10 m²) specimens and perform measurements in real buildings with similar test conditions as in laboratory. For evaluation of the specimen size influence on reduction in impact sound pressure level ΔL_W value sand/cement screed area discreetly was reduced from 13.4 m² down to 0.5 m². The test results showed strong dependence of reduction in weighted impact sound pressure level from specimen size. Relying on the test data it was derived relationship which could be applied for the correction of the determined ΔL_W values when smaller size specimens (area < 10 m²) of floating floor constructions are used.

DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1350

Original scientific paper https://doi.org/10.2298/TSCI180719299SDuring the design of energy-efficient buildings with a ventilated façade systems, the evaluation of point thermal transmittance is complicated. It requires additional theoretical knowledge, special software and skills to use it. Because of that, point thermal transmittance is often ignored in practice. The dependence of point thermal transmittance, which is appearing because of aluminum fixing elements used in the insulated wall with ventilated façade system, from the thermal and geometrical properties of construction layers are analyzed in this paper. Research has shown, that thermal properties of the supporting wall, where fixing element is located, had the biggest influence on the point thermal transmittance. When thermal conductivity of the supporting wall was increasing, as well as a thickness of the insulation layer, a value of thermal bridge was increasing in a non-linear way. For this reason, the thermal transmittance coefficient of all construction could increase up to 35%. When the thickness of the supporting wall and thermal conductivity of the insulation layer was increased, the value of point thermal bridge was decreasing. The tests revealed strong dependency of the point thermal bridge on the thermal conductivity of bearing layer material and the thickness of the bearing layer of wall. For this reason, thermal bridges should receive greater consideration. It is not enough to use the diagrams of typical fasteners that very often do not take into account the exact thickness and thermal characteristics of materials

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