All building materials can be affected by microbiological agents during their lifecycle. The presence of microorganisms changes the appearance of the surface, degrading it, and they can even cause health problems to the residents. The biological susceptibility is dependent on the content of nutrient based on organic compounds. Thus one of the most susceptible of those materials are earthen construction materials. The degree of fungal growth is influenced by the chemical composition and plant fibres additives as well as the external conditions such as temperature and relative humidity.
The earth plastering mortar has started to gain more attention recently as it is considered to have a low environmental impact and to increase the indoor air quality. Mechanical and physical characteristics of earth materials were studied by a number of authors but the knowledge about the biological resistance of the material is scarce.
This study intends to look into the issue of the biological colonisation of earth plasters depending on the relative humidity. The samples, made of four types of earth plasters with different plant fibres, were placed to an environment of the relative humidity ranging from 33% to 100%. During a period of 4 weeks the extent of fungal growth was observed.
Authors:Nóra Péterfalvi, Boglárka Keller, and Marianna Magyar
, Field J.P. , Felix O. , Corral-Avitia A.Y. , Saez A.E. , Betterton E.A. , 2014 . Effect of wind speed and relativehumidity on atmospheric dust concentrations in semi-arid climates . Sci. Total Environ. 487 . 82 - 90
Main aim of this paper is to illustrate the experimental partial results of a study on various exterior wall fragments. The study was performed for selected wall fragments and time periods, with attention focused also on wall orientation (East and South) with identical layering and also on dynamic thermal parameters connected to the thermal comfort during summer and winter. Evaluation is done for real measured climate conditions in the area of experimental laboratory (exterior – University of Zilina) and interior conditions set according to the Slovak standard. For needs of the long-term experiment (since March 2017), temperature and relative humidity between layers are monitored. This paper deals specifically with the temperature measurement of selected days. For future publications also coupled heat-air-moisture transport analysis is intended. In this part of analysis, some extreme boundary conditions were selected and reviewed from the point of view of measured temperature inside the wall. Temperature peaks are characterized with respect to exposure to real atmospheric conditions.
Authors:Pavel Soudek, Lubor Kalousek, and Antonín Žák
This paper is focused on hygrothermal assessment of the eave overhang detail in above-rafter placed thermal insulation roof system. Results of the long-term measurement of this detail performed on a real building as well as the testing of the measuring method are presented in this paper. Within this measurement the moisture of wooden elements performing an eave overhang of the roof was monitored primarily in order to verify their long-term functionality. In addition the temperature and relative humidity in the roof structure were measured as well. As part of this measurement, various design variants of above mentioned detail in combination with different compositions of the roof structure were compared. The long-term functionality of the assessed details is evaluated in the conclusion of this paper, taking into account especially hygrothermal status of wooden element, which is associated with threats of infestation of these elements by wood decaying fungi or insects.
Proper understanding of sorption behaviour of the materials is important from the point of view of fundamental research and technology as well for applied building technology. In this paper a simple method is presented for measuring water sorption capability of solid bodies. Moisture sorption and desorption measurements were carried out on soil samples by using climatic chamber. After drying the samples in a Venticell 111 type drying equipment they were treated with a Climacell 111 type climate chamber, where the relative humidity (RH) was varied from 40 to 83% at 22°C for different times (40, 80, 120 and 240 minutes). The samples reached the equilibrium moisture content after 120 minutes for sorption. The desorption isotherm measurements were carried out at 22°C for 80 minutes of exposure at constant RH. At this point hysteresis phenomenon was observed. Besides the moisture content figures the time evolution of the damping process is also presented in this paper.
The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.
These days, the investigations of the physical properties of the insulating materials are very important. In this paper we report the measured water uptaking capabilities of a thermal insulating paint. They can be found in liquid phase, but we measured dried solid samples. The thin thermal insulators (insulator coatings) are starting to spread on the market of the building materials. The proper understanding of sorption behavior of the materials is important from the applied building technology point of view. Moisture sorption and desorption measurements were carried out on two samples with different geometry by using climatic chamber method. After drying the samples at 90 °C for one hour in the Venticell 111 type drying equipment they were wetted with a Climacell 111 type climate chamber, where the relative humidity (RH) was varied from 25% to 90% at 293 K for 2 hours. The samples were wetted for 2 and 4 hours as well. Sorption and desorption as well as kinetic curves are presented in this paper.
The paper is focused on the influence of air distribution in modern large university lecture hall on the thermal comfort. Providing the optimal parameters of the thermal comfort in the interiors of a university is immensely important for the students. Meeting these parameters is inevitable not only from physiological point of view but also to achieve the desirable students' performance. Parameters of the thermal comfort are also influenced by air distribution system in large university lecture hall. Correct position of supply air and extract air is very important. Experimental measurements of thermal comfort were carried out in the winter season in the large lecture hall of Vienna University of Economics and Business. The device Testo 480 was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature, indexes PMV and PPD are presented in the charts. Modern air distribution system and air conditioning system of the large university lecture hall were evaluated on the basis of thermal comfort parameters. Conclusion of this paper states the principles of how to design modern air distribution systems and air conditioning systems in the new large university lecture halls.
Numerical research in the context of urban in a humid continental climate zone is still limited. The aim of modeling the case study is to assess the performance of outdoor thermal comfort parameters and investigate their capabilities in achieving the outdoor thermal comfort. A computer-based tool is used to quantitatively study the outdoor thermal comfort and its weather parameters. The parameters have been analyzed using ENVI-met tool and then compared against different comfort scales like relative humidity comfort scale, the predicted mean vote scale as well as other scales and standards. The results have shown that the average predicted mean vote value is +4 (very hot), the average air temperature is hot, the average wind speed is light breeze and the relative humidity falls within the comfort range. However, street orientation, shading, water bodies and plantation play a significant role in increasing and decreasing the outdoor thermal comfort.
Indoor air quality is a major part of indoor environmental quality and plays an important role in creating sustainable and healthy indoor environments. Well-being, health and comfort are affected by indoor air quality. The measurements that are introduced in this research paper were used to record the results of three different residential interiors. These data are a part of a larger scale research project that included the evaluation of residential buildings, offices, university interiors and for instance nurseries. The reason behind conducting the measurements in these interiors was that in all of the examples inadequate indoor air quality and therefore human discomfort, illness and also building failure occurred.
In this paper the theoretical background of the research and the measurement of indoor air quality (indoor air temperature, relative humidity level and carbon dioxide level) will be introduced. The poor indoor air quality in these buildings is a result of a complex system. The thermal bridges of the facade cause cold interior surfaces, the airtight solutions cause high relative humidity levels. These two combined result in mould appearance. Besides, the lack of appropriate ventilation rate can be the third part of the reason behind poor indoor air quality.
Based on the results of the measurement data, different solutions are suggested in each case to improve indoor environmental and air quality, in accordance with creating healthier indoor environments.