Applied Mechanics and Materials Vol. 824

Abstract: This paper defines the hygrothermal material properties (thermal conductivity, density, specific heat capacity, vapor diffusion coefficient and resistance, moisture storage function, water absorption coefficient and liquid transport coefficient) of steel fiber reinforced concretes that are widely used for industrial floors, based on laboratory measurements. The measured and calculated material properties are necessary to carry out a dynamic heat and moisture simulation of a component or a building containing steel fiber reinforced concrete layers.

Abstract: This paper highlights wetting measurements and results carried out on four different generally used construction and some insulating materials, executed in our Building Physics laboratory in University of Debrecen, Faculty of Engineering, Debrecen, Hungary. The measurements focused on the initial state of the water up-takin procedure (240 min wetting) only, waiting for the equilibrium moisture content was not a goal of this paper. Currently, Aereated concrete, small solid brick, Porotherm and ceramsite-concrete structural members are usually applied in building structures. The measurements of water sorption investigations are so significant from the point of view of thermal sizing of the buildings. To put it simply this article can be imagined as a short time wetting sorption database comparing with our previous results, besides this article can be very useful for everyone in building physics and in building engineering. In addition building materials, insulating materials were tested and will be put forward, as well, eg.: expanded polystyrene, extruded polystyrene, poly-urethane, and some fibrous materials. Totally, 11 materials were investigated, after drying in a Venticell 111 type desiccator apparatus at 343 K to changeless weight and then wetting in a Climacell 111 type climatic chamber, where the relative humidity was varied from 25% to 95% at 293K for 240 min. As result, new isotherm curves for this short time wetting will be presented and will be compared to the literature data, MSZ-04-140-2-1991.

Abstract: Recently, there has been increased interest in the rehabilitation of existing buildings especially in order to improve their energy performance. Thermal insulation brings not only savings in the cost of heating or cooling but also contributes to the reduction of harmful emissions such as carbon dioxide, sulphur dioxide or nitrogen dioxide. However, the thermal insulation of historical buildings or buildings listed as cultural heritage brings some problems due to architectural features. It is therefore necessary to choose an alternative whether it is the use of an internal thermal insulation system or to repair and rehabilitate the existing plaster with materials compatible with the original ones. The newly developed thermal insulation plasters based on silicate and using lightweight aggregate and natural fibres are optimum materials for the thermal insulation of both existing and newly constructed buildings. The paper describes the results of research focused on the examination of the behaviour of thermal insulation plaster mainly in terms of heat and moisture transport. Using a computational programme, this behaviour was simulated for a chosen detail of a real building in the vicinity of a window jamb.

Abstract: The article presents results of oriented strand boards moisture testing series. These boards are often used as important vapor retarders and as a part of load bearing structures for timber housing. Changes in the original values of structural physical properties were tested and monitored in laboratory. Performed experiments proved significant differences in physical properties of structures based on organic materials after exposure to for instance water flooding accident.

Abstract: Determination of the surface temperature in order to evaluate the risk of mould growth is currently already a common task. Good knowledge of boundary conditions is necessary for precise evaluation of this risk. Standardized requirements are suitable for a preliminary design and a general comparison of various assembly details, as they help us understand how these details will work (in defined boundary conditions). But the real user behaviour varies greatly and is not always in agreement with the standardized requirements. Air humidity is one of the parameters which significantly influence the mould growth. It varies depending on the use of the building and especially on the number of moisture (humidity) sources. To determine the production of moisture by different sources we built an vaporization climatic chamber, where we monitor the production of moisture in dependence on relative air humidity and air temperature.

Abstract: The paper is oriented on the analysis of the ventilation systems in schoolrooms. Correct and sufficient ventilation of schoolrooms is very important because students and pupils spend in the schoolrooms the majority of their time in school. In our schools the ventilation is incorrect and insufficient. The biggest problem is winter period when the ventilation is provided only by opening the doors to corridor. This way, there is insufficient intake of oxygen, which causes distractibility and feeling of tiredness of pupils. In current schoolrooms we can use only natural ventilation and thus the schoolrooms have to be ventilated using windows. Therefore this research was focused on the comparison and the analysis of different systems of natural ventilation in schoolrooms. The experimental measurements were carried out in schoolroom, where the parameters of thermal comfort were measured in the different systems of natural ventilation with device Testo 480 which was connected to computer. Gained values of air temperature, air velocity and index PMV are presented in graphs. On the base of analysis of measured values were evaluated the systems of natural ventilation for schoolrooms. In the future, the mechanical ventilation in schoolrooms can be assumed, therefore the recommendation on modern energy saving system of mechanical ventilation is in the end of this paper.

Abstract: The paper describes the importance of monitoring the dust in the atmosphere of human life. It deals with the issue of dust in air ducts, approaching the methods that can be used to detect the amount of dust. For conditions for buildings in the Czech Republic there is created the methodology of quantitative and qualitative evaluation of dust sediment for the needs of HVAC and other building surfaces. The scale for visual evaluation was created and it has been elaborated the assessment of kind of particles contained in dust.

Abstract: Ventilated façades help to protect buildings against overheating during the summer seasons. The efficiency of this function depends on many factors. The geometry of inlet and outlet openings may be the significant factor of the ventilated façade function. This study presents the experimental assessment of the outlet geometry influence on the temperatures and airflow in the open joint ventilated façade. Two sections with different outlet geometry are compared in the same time. Different types of outlet geometry are based on various window sill dimensions and various cross section dimensions between cladding and window sill. The cavity temperature and airflow differences are assessed during the direct insolation of façade sections. Results show that the effect of outlet opening area is much more significant than the assessed outlet geometry types.

Abstract: The article deals with optimization of thermal and moisture conditions in the indoor climate of ventilated buildings. Case study is aimed at examination of thermal and velocity fields and thus optimization of air distribution in the social hall. The issue was solved by computational fluid dynamics simulation. The mathematical-physical model was created for characteristic part of the social hall. The obtained results implicate that usage of jet nozzles is more suitable than usage of air registers for large hall due to air registers’ short-range of the air flow.

Abstract: The paper deals with risk analysis of insufficient airtightness of the envelope construction. The risk analysis is a systematic and structured data processing to identify potential hazards. The main aim of paper is to qualified risks which arise from the danger, i.e. insufficiently airtight of the building envelope. The quality of airtight building envelope except for low energy consumption also minimizes the risk of damage to the structure associated with the spread of the heat, water vapor in the structure and fungal growth. The qualification of risks consists of choice of method and determinative indicators, input data and simulation of model with drawing results.