The paper deals with determination and classification of the mechanical parameters of cement fibre boards (CFB) with cellulose and PVA reinforcing fibres. The cement fibre material with reinforcing ...fibres is produced using the Hatschek process, where the fibres are arranged in the production direction and the curing is subsequently verified. Test experimental samples, specimens are created from the same production batch, and are produced orienting all of them in the production direction to determine the characteristic for an orthotropic material. The fracture mechanical parameters such as fracture energy and work of fracture were then determined and verified as well. Records will be made for the determined crack mouth opening displacement (CMOD) and displacement (d) of test specimens. The loading directions are given to cover the determination of the mechanical parameters of the material. These measurements are intended to complement the mathematical model that uses FEA modelling for subsequent implementation of the material into civil engineering structures or details.
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•Determination of fracture properties of CFB with cellulose and PVA fibre.•A new CMOD measurement method was developed for smaller test specimens.•The obtained fracture energy values were implemented in the FE Analysis.•Validation of the numerical model with fracture parameters via experimental tests.
Daylight has been used for centuries as the main source of light in the interior and has always been an implicit part of architecture since the buildings existed. Not only does it replace electrical ...lighting during the day, reducing electric power consumption, but it also affects heating and cooling, making it an important parameter in energy efficient design. Research has shown that daylight is a great asset to health and comfort, so it is crucial for building occupants. Daylighting of the interior spaces of buildings and their functionally defined parts is proposed according to visual activities. The minimum values for daylight factor are set for individual visual activities. This article deals with factors influencing the value of the daylight factor.
Daylight has been used for centuries as the main source of light in interiors and has always been an implicit part of architecture ever since buildings exist. Daylight is an irreplaceable ...environmental factor and is a prerequisite for a healthy stay in buildings. Ensuring daylight access to the interior is a challenge when designing buildings. The aim is to provide enough daylight for the visual work that indoor building users do. The deposition of air pollutants on the glazing can significantly affect the transmission of daylight into buildings located in urban areas. This study shows the impact of air pollution on glazing permeability in three cities in the Czech Republic. The throughput was measured on a total of 9 windows for half a year. Air purity, exposure to rain, the slope of glazing and use of rooms are factors influencing the final permeability of the glazing. Where glazing is exposed to rain, dirt on the outside of the windows tends to accumulate. The final reduction in throughput is usually 4-8%, with some exceptions.
Daylighting simulation programs use different methods and algorithms for illuminance calculations in buildings. It is widely known that results of different lighting simulation programs does not have ...to be the same for two or more identical rooms. Hence CIE issued Technical Report 171: 2006 which presents test cases to assess the accuracy of lighting computer programs. However, these test cases are simple and the accuracy of daylighting computer programs can be different for more complex cases. The purpose of this paper is a comparison of differences in the results computed by various daylighting simulation programs for selected test cases according to CIE 171: 2006 and for more complex cases.
Lighting conditions in buildings are verified by experts on a daily basis. Such verifications may be done at several phases in various ways. In the field of daylighting, it is common to make an ...assessment within the pre-design and in-design phases of a construction work throughout calculations, only rarely by measurements. This approach is the opposite of artificial lighting design, which is done within the in-design phase by calculations and is verified by measurements in post-realization phase. The verification of artificial lighting design is required by the building and public health authority otherwise buildings cannot be approved to use. In the field of daylighting, measurements could be performed as well, nevertheless those are often problematic because regulations usually require fulfilments of the daylight factor which can be determined only under CIE overcast sky. Howbeit, both artificial lighting and daylighting measurements are influenced by many errors, e.g. errors of light measurement instruments, measurement conditions, measurement methods and human factor. The paper is focused on this aspect of lighting design, more specifically on the daylighting measurement errors.
The issue of the efficiency of use and determination of the operational efficiency of the designed light sources is relevant during the process of lighting design. The contribution deals with the ...illumination of the interior by the tubular light guides during design and operation itself. The measurement of the luminance, the illumination of the exterior and the interior was carried out on experimental wooden building in Brno belonging to VUT FAST (Czech Republic). In one case, the brightness of the sky was also measured. The assessed tubular light guides Sunizer with the length of tube 2 m and with the diameter of 320 mm passes through the roof structure and through the ceiling structure into the interior corridor of the wooden building. Prior to the start of the measurement, the measuring sensors were placed in the center of the diffusers of the two measured tubular light guides at the floor level. Another one sensor was placed at the midpoint between the diffusers at the floor level. Subsequently, another sensor was placed on the roof of the building in the exterior. The sensor is placed next to the dome of the light guide so that it is not overshadowed. The sensors were connected to the datalogger and the 5-minute measurement was performed at all four locations simultaneously at time intervals after one minute. The values of the sky brightness always in four directions were determined were determined before the measurement, in the middle of the measurement and at the end of the measurement. The sky type was determined visually for some of the measurements. Finally, the measured data from the luxmeter was stored and the ratios of illumination of the interior and exterior were calculated. Subsequently, the measured data are compared with the simulations obtained from the software Holigilm and Velux Daylight Visualizer. The benchmark is the ratio between indoor and outdoor illumination, the so-called daylight factor. Finally, there is an evaluation, a graph showing the difference between these values and the explanation of the differences of results between the real measured values and the outputs from the simulation programs.
Indoor visual comfort is one of the leading requirements for building design. Results of computer daylight simulations serve to optimise the design process. Computer programs Ecotect and Radiance ...were used for the simulation of daylighting from tubular light guides of various diameters and lengths. The internal illuminance calculations were compared for two extreme situations in boundary conditions - sunny summer sky and winter overcast sky, determined for the climatic region of Central Europe. Daylight simulations give information about indoor illuminance on vertical and horizontal reference planes depending on various dimensions of the light guides. Finally, the assessment of annual variation of average internal illuminance from light guides under different outdoor climatic conditions - for uniformly overcast sky, intermediate sky, clear sky and sunny sky - was completed. The simulation results serve to evaluate daylighting and visual comfort in interiors illuminated from light guides.
The assessment of the variation of average internal illuminance from tubular light guides under different outdoor climatic conditions. Computer program Radiance was used for simulations of ...daylighting from tubular light guides of various dimensions. The internal illuminance calculations were compared for two extreme situations in boundary conditions - sunny summer sky and winter overcast sky, determined for the climatic region of Central Europe. Daylight simulations give information about average indoor illuminance on vertical and horizontal reference plane in the dependence of various dimensions of the light guides. Results of computer daylight simulations serve for the design optimization.
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