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Building components in terms of thermal protection are being addressed with standard requirements to related thermal performance design. In this relation, thermal conductivity parameters play a highly relevant role that may affect heat transfer greatly. This represents a key factor in building performance assessments for steady-state conditions and corresponding calculation models on thermal effectiveness as well as temperature distribution of building components. Generally, these parameters are known from declared values given by their producers. For this purpose, standard tests are performed to provide data under steady-state conditions. However, limitations may occur in real cases due to not constant and changing thermal conductivity that is temperature, moisture, and time-depending variables. Therefore, in the design process, several governing factors should be carefully considered in thermal calculations. Accordingly, a standard methodology using the transformation of declared values to design values is adopted in practice. In this paper, the usefulness of transformation formulas based on standard methods is demonstrated and discussed as compared with real subjections obtained in the laboratory. One of the representatives of thermal insulation based on mineral fibrous material was used and studied experimentally to obtain transformation factors on both moisture and temperature relations. Based on the data measured, coefficients of transformation formulas were derived from experimental measurements. Results identify a certain discrepancy between experimental data and theoretically calculated values used by available standard methods. [ABSTRACT FROM AUTHOR]

Paper presents theoretical and real hygrothermal behaviour of the south-east timber wall component. The analysed wall component represents current trends in wooden house design and it is a part of experimental timber building in campus of Mendel University in Brno – woodenHAT experimental module. Long-term exposure of the experimental module to real weather conditions brings information about real of hygrothermal behaviour. The component contains several temperature and moisture sensors which together with the weather station permanently monitor temperature and moisture content in the wall component and conditions in front of the façade during the whole year. Experimental data are compared with results of dynamic simulation earned by well-established software for prediction of heat and moisture transport Delphin which has been developed by Institute of Bauklimatik at TU Dresden. Boundary conditions of the numerical model are based on local weather data as well as reference year for closest places near to Brno. The analysis shows and discusses differences between results of experimental measurement and selected boundary conditions. It represents the validation of HAM-modelling for cases neglecting air flows and insufficient airtightness. [ABSTRACT FROM AUTHOR]

There are still requirements in the building energy research and thermal engineering field to increase the thermal performance of a building and its structural elements. Building envelope made of hollow ceramic bricks are widely used in building engineering for their thermal, acoustic, and structural properties. This type of building element can be considered as one of the most used technologies for the present walls of building envelopes in European region. Various aspects that affect the resulting geometry of brick hollows, changes in the configuration of cavities and currently also the application of filling material with low thermal conductivity may contribute to the increase of thermal properties of these bricks. Another potential approach and further improvements can be based on the reduction of heat loss during heat transfer through the brick cavities aimed at reducing heat transfer by thermal radiation. Therefore, the effect of low emissivity on the thermal performance of ceramic hollow brick is the key subject of this paper. For his reason, inner surfaces of brick cavities were modified with low emissivity coating, experimentally tested using a heat flow meter method and to provide a consequent numerical analysis. Results presented in this study reveals, that depending on the emissivity, the decrease of the thermal conductivity of up to 20% can be theoretically achieved when particular hollow bricks are modelled however this effectivity is not followed by experimental measurement. [ABSTRACT FROM AUTHOR]

The current development of modern building envelope systems predestines the relevance of the application of specific test methods for it to adequately characterize thermo-optical properties of novel transparent building components and systems. Therefore, the intention of this study concerns the investigation of the spectral test method for its potential implementation in analyzing thermo-optical changes in a phase change material based on building components. As solar simulators are considered to be the key methodologies for conducting solar-based research under a well-controlled environment, this study presents a simple design of a low and high flux solar simulator to provide optical testing of specific glass components. The optical system was designed as a lamp of one unit and a parabolic reflector used to irradiate test samples implemented in a squared box with an optical detector. Second, the experimental setup was equipped with a spectrophotometer, and the validity of transmittance data obtained with a reference building's transparent systems, like a simple glass pane and Plexiglas, was tested by measurements comparison with results obtained using a UV/VIS/NIR spectrophotometer in the light transmittance spectra. The results of the experiment revealed light transmittance data obtained from spectrophotometers and compared with reference simple glass systems. [ABSTRACT FROM AUTHOR]