Assessment of Cumulative Damage of Selected Building Envelopes Exposed to Various Environmental Effects

Hygrothermal performance of building envelopes based on three different building materials (solid brick, high performance concrete, aerated autoclaved concrete) is assessed under climatic conditions of Prague and Atlantic City. Main objective of the paper is to evaluate the influence of cumulative damage, which was induced by means of natural weathering in 2012- 2015 period, on the long-term performance. The performance is assessed using various measures, namely time-of-wetness function, number of freeze/thaw cycles, and annual amount of energy transmitted through the envelope. The results show that thermal performance of the envelopes gets mostly better after weathering as the annual amount of energy is decreased by ~3.5% in average. On the other hand, time-of-wetness function and number of freeze/thaw cycles increase by ~24.1% and ~22.0%, respectively. Based on the results summary it can be concluded, that cumulative damage of materials has an indisputable influence on the hygrothermal performance of building envelopes which might be either negative or positive. A detailed computational assessment is therefore necessary, incorporating not only reference, but also weather-affected material properties

Experimental analysis of micro-cracks on the change of moisture transport properties of AAC

In this paper, series of experiment measurements is carried out in order to study effect of freeze/thaw loading on the change of moisture transport properties of autoclaved aerated concrete. The samples were subjected to 15, 30 and 45 freeze/thaw cycles and subsequently basic physical properties, pore size distribution and water vapor and liquid water transport properties were investigated. The results showed significant changes in material properties of the material. The results of this research can be further implemented into computational models in order to bring the simulation results closer to the reality

Service Life Assessment of Historical Building Envelopes Constructed Using Different Types of Sandstone: A Computational Analysis Based on Experimental Input Data

Service life assessment of three historical building envelopes constructed using different types of sandstone is presented. At first, experimental measurements of material parameters of sandstones are performed to provide the necessary input data for a subsequent computational analysis. In the second step, the moisture and temperature fields across the studied envelopes are calculated for a representative period of time. The computations are performed using dynamic climatic data as the boundary conditions on the exterior side of building envelope. The climatic data for three characteristic localities are experimentally determined by the Czech Hydrometeorological Institute and contain hourly values of temperature, relative humidity, rainfalls, wind velocity and direction, and sun radiation. Using the measured durability properties of the analyzed sandstones and the calculated numbers of freeze/thaw cycles under different climatic conditions, the service life of the investigated building envelopes is assessed. The obtained results show that the climatic conditions can play a very significant role in the service life assessment of historical buildings, even in the conditions of such a small country as the Czech Republic. In addition, the investigations reveal the importance of the material characteristics of sandstones, in particular the hygric properties, on their service life in a structure

Society of Humpolec: Singing society Čech and Lech

The aim of this bachelor thesis engaged in the activities of the Musical club Čech and Lech in Humpolec from 1862, when the club was founded, to interruption his activities in 1951. Part of work is a brief history of Humpolec, used to capture the social contexts of the club. Next is attention focuses on the organization and administration of the club during his activities or affairs of members. Disassembly the members of the club are important, their origin and social activities, as well as the membership base and the cultural and social activities of the club

Selection of security software for user data protection

This work shows overview of potential electronic threats with which present users can come in contact. This topic is very common theme and we can hear about malicious programs or malware almost from the very beginning of computer age. Therefore, in this work, I try to provide view into the most common threats. But the main goal is to find the best solution for protecting user data against malware. Therefore, in the practical part I tested ten most used antivirus programs. The result of this test should show objectively which solution is for the user the most appropriate in terms of several criteria. The criteria that I chose are, detection ability, system memory usage and the total length of the test

Experimental determination of length changes of autoclaved aerated concrete during the freeze-thaw cycle

The aim of the paper is an experimental determination of the longitudinal expansion of autoclaved aerated concrete (AAC) during the freeze-thaw cycle. Longitudinal changes were measured with lasers and the surface temperature was measured using an infrared temperature gauge. The temperature distribution over the sample was verified by a numerical calculation

Numerical simulation of degradation of porous building materials caused by freeze-thaw cycles

Freeze-thaw cycles in porous building materials are studied in this contribution. Degradation and durability of many building materials as well as structural elements are tightly connected with the freeze-thaw cycles. The porosimetry curve and Gibbs-Thomson equation are used for estimates of volume changes caused by the freeze-thaw cycles. The volume changes are used in mechanical analysis based on the isotropic damage model. Numerical example documents the approach proposed

Determination of effective specific heat capacity of interior plaster containing phase change materials

A precise technique for determination of effective specific heat capacity of building materials is presented within this paper. The applicability of the technique is demonstrated on a PCM-enhanced plaster, being characterized by a phase change between 15 and 30 °C. The effective specific heat capacity is determined by means of inverse analysis of calorimetric data using computational model of the device. The identified effective specific heat capacity values reached up to 1890 J·kg-1·K-1 when cooled and 1580 J·kg-1·K-1 when heated. Using this quantity in simulation of thermal performance, the PCM-enhanced plaster showed to have a promising potential to be used in buildings’ interiors as a thermal regulator to stabilize inner environment as it contributed to a thermal oscillation decrease by up to 2.5 °