Applied Mechanics and Materials Vol. 824

Abstract: The energy efficiency minimum requirements determined at the Decree 2006/7 by the Minister without Portfolio, has been amended in 2015, only prescribes cost optimisation levels corresponding in strictness to those by the European Union as set out in the Directive 2010/631 EU for state or EU founded renovations. With the artificial decrease in energy prices in Hungary in 2012, requirements originally considered as optimal has changed and tightening is not needed any more. By maintaining the old requirements, the energy consumption and CO2 emission of renovated and newly constructed buildings will stay below optimum levels. Ignoring actual energy prices results in an apparently low return on constructing energy efficient buildings while energy awareness is also decreasing as a result of these measures. One may wonder about the energy efficiency measures that could have been financed from the savings coming from the enforced utility cost reduction, ones that would have resulted in real energy savings, thus benefitting both the users of buildings and the implementation of Hungarian commitments with the deadline of 2020.

Abstract: This paper exams the dependence of soil temperature fields of basement structures of buildings on the type of the surrounding soil. The 3D simulation model is based on data from real measurements of soil temperatures during the winter over a period of two years. The measured data were incorporated into the model on the basis of statistical evaluation. The basic aim of this paper is to approach, as closely as possible, the individual effects of basement structure construction on the soil temperature field on the basis of real measured values.

Abstract: This article describes some microclimate parameters in chosen production building and their influence on the whole energy consumption for heating in winter period. The article presents the monitoring of physical aspects of chosen hall object, which is in poor technical condition. The content of this contribution is the comparison of energy saving according to indoor conditions in selected industrial object in the present state. The article deals with hygrothermal parameter analysis in industrial production building, considering the effects on energy consumption for heating.

Abstract: Temperature stability of a room is of a high relevance to achieve an optimal level of built environment. Standardized calculation models of temperature stability are determined by international standard ISO 13792 based on recently developed empirical models whose approximations can finally be applied. It basically describes two models, however both demonstrate approaches that may not have the best conformity when confronted with the reality. Thus the research objective is to point out an applicability of given calculating models. The paper presents a validation proposal with aim to find an applicable correlation related to current methodology. Finally as result of this study, proposed approximations could demonstrate better consequence to the reality.

Abstract: Computational numeric thermal bridge simulation can be considered a state-of-the-art technology for evaluating the thermal behavior of building component intersections. Conductive processes (and with some restrictions convective and radiative processes as well) inside of building details can be evaluated; Such analyses can help improve and optimize constructions. This can be necessary to ensure the durability of constructions and to avoid increased heat flow, low surface temperatures, and condensation problems. Numeric simulation tools regularly use finite differences methods, which approximate reality to a high degree. This requires the geometrical representation of such a thermal bridge to be discretized as a uniform grid. This – as a consequence – requires models that are reduced to strictly orthogonal structures, which has a large impact on the modelling of building joints with sloped or rounded surfaces and elements. Such elements need to be simplified to orthogonal elements, resulting in step-by-step representations of slopes and curvatures. While the accuracy of thermal bridge simulations is considered sufficient, the modelling efforts of such details and their simplification often represent a time-consuming and error-prone activity.In this context, the contribution presents recent efforts in the development of the state-of-the-art tool AnTherm (www.antherm.eu) that allow the automated generation of slope and curvature representations within the modelling canvas of the tool. As a consequence, the modelling and simplification of sloped and rounded elements can be done fast and with a high degree of accuracy. This contribution describes the general method, its implementation, an analysis of the overall usability of the approach, modelling examples and an outlook to future developments.

Abstract: Thermal stability of the indoor environment in summer period is influenced by the local characteristics of the building site, building geometry, orientation of glazing, heat storage capacity of structures, method and intensity of ventilation, but also the size and characteristics of transparent surfaces and associated heat gains from sunlight. The intensity of solar radiation is a very important parameter that affects the temperature in the room. As a boundary condition in computer simulations is used “Reference climatic year”, but the values are more or less different from the actual measured data. This article presents a comparison of the dynamic calculation of the temperature in the room with the real measured values. In addition, the calculation is modified by substitution of actually measured climate data.

Abstract: The article describes the summer thermal stability of a semidetached passive house in Moravany - Czech Republic. Long-term measurement was carried out on the uninhabited house. The house is divided into two symmetrically identical residential units. Indoor air temperature differences of these symmetrically identical rooms are compared. Comparative numerical simulation was also carried out.

Abstract: The temperature and relative humidity measurement in building physics needs special equipment which is often expensive and not available for young researchers. Several programmable platforms are available. This article describes the low-cost solution of temperature and relative humidity measurement using combined Digital Humidity/Temperature sensors and Raspberry Pi as the datalogger. Five lightweight timber frame wall fragments with various thermal insulations and outdoor coating colors were exposed to the real outdoor boundary climate conditions. The indoor boundary conditions were secured as constant. The results of measurement using low cost sensors were compared to values obtained by commercially available thermocouples for scientific use and non-steady HAM simulation in WUFI software.

Abstract: This article focuses on hygrothermal problems in massive wooden sandwich structures. Wood in sandwich structures is already artificially dried before processing, and therefore does not further shrink, as it does in the case of log cabins. Analysed sandwich structure is composed from three layers, and is formed of wooden beam in interior side, thermal insulation and wooden beam in the exterior side. The composition of analysed structure is considered in different thickness with respect to the required heat transfer coefficient. Massive wooden beam on the exterior side causes troubles which exhibits in the reducing capacity of diffusion of water vapor. It is therefore possible that water vapor condenses on the interface of wood and the thermal insulation under certain boundary conditions. Therefore, it is appropriate to place massive wooden beam closest to the interior side. This solution would improve the balance of the diffusion permeability to water vapor permeating from the interior side to the exterior side.

Abstract: The article is focused on the study of the water vapour diffusion through the vapour retarder at its varying percentages of damage. Two different kinds of foils are used as a vapour retarder. This experiment points to the actual value of the diffusion values of building materials contrary to the values obtained from the tests according to ČSN EN ISO 12572. In these tests the building material is exposed to various boundary conditions and its parameters are monitored. The final value is the result of approximation of different values, which in the real installation may not correspond to the boundary conditions in a building.