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Assessment of ventilated floors construction
Jurka, Jiří ; Kmínová,, Hana (referee) ; Šilarová,, Šárka (referee) ; Šťastník, Stanislav (referee) ; Škramlik, Jan (advisor)
Air insulation, especially its efficiency, is often underestimated and most often it is recommended as combination of several methods by our experts. It is known that flowing air used to eliminate excessive humidity in lower construction is insignificantly promoted. Already our ancestors in ancient Rome had experience with implementation of air insulations. However, nowadays such design is connected with many doubts and it forces us to use sense, especially knowledge of construction physics. So it urges higher technical precision when designing functional ventilation system. Each building is actually a unique object, with regard to its position and used properties, that is why certain natural conditions must be accepted when designing. It is more complicated and figuratively speaking it can be written in c. 20 equations of twenty unknowns. Other problems arise in unknown coefficients to individual parameters and their effects. From another point of view it is the issue of changing air during the day, passing fronts, annual cycles and all of these in relation to internal environment of the building, materials used in the construction, land properties of rocks, and last but not least, relation to the terrain around the building. Then there are the effects of the building's altitudes etc. In total they are cycles with sine character of dampening and drying. The thesis discusses how to test the functionality of AIR insulations designed for the floor ventilation in historic buildings and follows on from the previously published articles. A flow analysis is being performed on an object of the city of Žirovnice which has been registered in the list of cultural monuments and was built as a brewery in the years 1589-1592 on the site of an older medieval building. This article brings new air-flow element. The aim of the article is to analyse in detail the air flow in a specific floor void with the aid of modern CFD programs and experimental measurements using the ALMEMO
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Validation options for increasing the thermal insulating properties of foam plastics
Smutný, Vojtěch ; Kopřivík, František (referee) ; Šťastník, Stanislav (advisor)
The thesis is devoted to the study of material properties of selected types of polystyrene, especially expression of the coefficient of linear thermal expansion. The work contains two main chapters, theoretical and practical. The theoretical part of the thesis deals with an overview of the thermal insulation in the Czech Republic, the description of phenomena related to heat transfer mechanisms and an overview of experimental methods for determining thermal insulating properties. The practical part presents results of measurements of samples with foamed polystyrene, which is modified by the addition of selected substances. The thesis describes the machine program, which is used to calculate the temperature in during the construction arrangement under the sunlight load.
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A rheology of high viscosity portland cement pastes applied on extrusion technology
Tihlařík, Petr ; Kunc, Jaroslav (referee) ; Lang,, Karel (referee) ; Šťastník, Stanislav (referee) ; Fridrichová, Marcela (advisor)
The aim of this doctoral thesis is to verify a possibilities of fibercement extrusion. A mixture for extrusion is typical for its high toughness and high fiber content, as the fiber content may be several times higher than when utilizing other production methods. The technology of a twin shaft kneader makes it possible to produce homogenous mixture for extrusion with low water/cement ratio. With use of auger moulder a mixture of high toughness is formed to final shape. The extreme shear and pressure stress is applied in the process. Therefore high requirements are posed on the equipment.
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The study of passive radiation finishes in construction
Kopkáně, Daniel ; Steuer,, Radek (referee) ; Kmínová,, Hana (referee) ; Chybík,, Josef (referee) ; Šťastník, Stanislav (advisor)
One of the key issues of our society is to decrease energy demand. About 40 % of energy consumption in Europe is related to building operation, mostly for heating. The required thermal comfort is related mainly to temperature of air and temperature of surrounding surfaces. Especially in older buildings with low level of thermal insulation the inner surface of perimeter wall can be several degrees colder than air. In such case the perception of thermal comfort will be lowered also depending on the layout of the room. Other issue can be related to thermal radiation asymmetry. The amount of energy that is eradiated from a surface is driven by material property called emissivity. A surface with sufficiently low emissivity will became “thermal mirror”. It is possible to elaborate about intelligent thermal management of the internal space with usage of low-emissive surfaces; where thermal radiation can be suppressed or can be enhanced. This depends on the surface emissivity and its real temperature. Recently, growing interest about the low-emissive surfaces can be seen. They can represent reasonable complement to conventional insulation, but they have certain limits. Potentially, even higher energy savings can be reached with so called retro reflection. If the thermal radiation of an object is reflected back, its thermal loss will be lower. In such case it can be expected that equivalent thermal comfort can be reached even with lower overall temperature of the room. The aim of the work is study of material combinations with potential for utilization as low-emissive interior surfaces. Research has been conducted on low-emissive paints and low-emissive foils. Another part of the work is related to retro reflection of thermal radiation as a potential way to influence thermal comfort. The work shows, that energy saving up to 20% can be obtained.
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Study of maturing process of volume stabilised floor flow screeds
Konvičný, Václav ; Štenko,, Miroslav (referee) ; Šťastník, Stanislav (advisor)
The diploma thesis is devoted to the comparison of drying processes of various types of poured floor self-levelling screeds under conditions close to construction practice, especially during maturation under different climatic conditions. These properties were observed by several methods. The course of strength increases and final strength of tested materials under different climatic conditions were also found and compared. The conclusion summarizes the knowledge about the course of drying and the course of development of strengthening of individual floor materials.
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Analysis of properties of openings with respect to infiltration in buildings
Zapletal, Miroslav ; Klepárník,, Jan (referee) ; Polášek,, Josef (referee) ; Šťastník, Stanislav (advisor)
The dissertation thesis is primarily focused on the analysis of the properties of openings constructions with respect to infiltration in constructions, specifically related to the permeability of opening fillings and the permeability of buildings. The main aim of this work is to find out how the overall air permeability of a building can be influenced in relation to the openings and their properties, which are related specifically to the air permeability at the specified tightening degree of the used all-round fitting. In relation to the overall air permeability of the building, the energy balance of a particular building will be calculated in cooperation with the determined results of the air permeability of the building at a defined degree of tightening of used all-round fitting at levels 0%, 50% and 100%. The results of tests and measurements will be reflected in a concrete calculation of the energy balance of the assessed building in the form of numerical simulation.
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Identification of Thermal Conductivity and Thermal Capacity of Building Materials by the "Hot Wire Method"
Průša, David ; Čermák,, Jan (referee) ; Šťastník, Stanislav (advisor)
This aim of task deals with study of heat dissipation mechanisms and the description of physical phenomena, which is accompanied by non-stationary measurement of thermal characteristics by the method "hot-wire method". In particular, we observe the coefficient of thermal conductivity and its dependence on various variables such as the temperature of the measured sample, its moisture state, the volume of the sample and its porosity. The above mentioned findings are used for the invention of the measuring device of a nonstationary gauge, which is based on regular heating and is dedicated to measuring the thermal conductivity coefficient and the heat capacity by the "hot-wire method" method. In the last part of the thesis is verified functionality of the proposed measuring device, the suitability of the created algorithm for the processing of the measured data and the evaluation of the results was verified. The reproducibility of the measurements was verified and the measured results were compared with the measurement methods, which are commonly used. the influence of humidity on the coefficient of thermal conductivity.
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