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Investigation of the process of heat transfer in the structure of thermal insulation materials based on natural fibres
(Elsevier, 2016-08-03) Zach, Jiří; Slávik, Richard; Novák, Vítězslav
Thermal insulation materials based on natural fibres are some of the promising materials that are currently emerging on the construction market. These materials are important especially in terms of sustainable development, since they utilise renewable raw material resources or secondary materials and their production does not consume too much energy. However, a problem with these materials is the rather different behaviour during heat and moisture transport compared with conventional insulation, which is made from synthetic (foam polystyrene) or inorganic (mineral wool) materials. The paper presents the results of a practical investigation into the process of heat transfer through the structure of thermal insulation materials based on natural fibres.
Studying the Properties of Particulate Insulating Materials on Natural Basis
(Elsevier, 2016-08-03) Reif, Martina; Zach, Jiří; Peterková, Jitka
Recently, materials based on secondary raw materials have been the focus of attention of building companies and end users as well. The reason for this are mainly the low material costs, easy manufacture and application in building structures. Despite the lower cost compared to existing insulation materials, strict requirements are put on these thermal insulation materials. In response to the constantly increasing need for insulation materials and given the general requirement of sustainability in the use of natural resources, the Faculty of Civil Engineering in Brno has for many years been engaged in the development of insulation materials made from natural fibres of agricultural origin. These materials show great promise in civil engineering. They have a low carbon footprint and low primary energy input. Experimental testing conducted in the past has revealed that the properties of these materials are comparable to those of the synthetic insulations available on the market. However, in terms of thermal insulation properties, the natural-fibre materials have different hygrothermal behaviour, which is due to the different structure of the insulations as well as the low value of thermal conductivity of the natural fibres (compared with e.g. glass or mineral fibres). The paper deals with the development of particulate insulation based on natural fibers, their behavior under different conditions and mainly with the examination of the thermal properties depending on moisture and bulk density. The paper also presents the results of research in the dependency of thermal insulation, acoustic and mechanical properties of the experimentally manufactured insulations on their bulk density.
Alternative technology of constructing masonry structures designed for areas with increased seismic activity
(Elsevier, 2016-07-21) Sedlmajer, Martin; Zach, Jiří; Novák, Vítězslav; Peterková, Jitka; Horský, Antonín
The Czech Republic is a country which generally sees low seismic activity; however, this activity needs to be taken into account in ca 50 % of the country’s area with 10 districts being considered as having seismic activity higher than 0.08 g. In terms of masonry structures, this issue concerns mainly the execution of the head joints of the masonry and its reinforcement (both in the direction of the bed joint and in the perpendicular direction). All these technologies are rather difficult and expensive to implement. The research focuses on assessing the possibilities of constructing dry masonry and binding it with polyurethane foam. This method allows for significantly higher shear strength of the masonry and appears to be an interesting alternative in the area of constructing buildings in seismically active areas. The structure was stiffened by filling hollow masonry units with large cavities with polyurethane foam. The PUR foam was sprayed into the units during construction. The foam thus applied hardens perpendicularly to the bed joint of the masonry and, having expanded throughout the clay units, it functions as a binder and a stiffening component to the masonry as a whole. The initial shear and flexural strength of the masonry segments was determined. The newly developed method of filling the cavities of masonry units with PUR foam was compared with the conventional method of constructing masonry by means of bonding the blocks with mortar or PUR foam in the bed joints (with no cavities filled). The filling of the masonry unit cavities brought a significant increase in the shear and flexural strength of the masonry. This indicates the stiffness of the structure increased as well.
Study of the Use of Vacuum Insulation as Integrated Thermal Insulation in Ceramic Masonry Blocks
(Elsevier, 2016-08-03) Zach, Jiří; Novák, Vítězslav
Vacuum insulation panels (VIP) are thermal insulation materials with very low thermal conductivity. VIPs are commonly used in a broad spectrum of technical fields; however, they only see a small-scale application in civil engineering. The reason is mainly their high price and difficulty of installation. VIPs are very vulnerable to mechanical damage, which typically causes the loss of their thermal insulation properties. This paper deals with the possibility of effective incorporation of these insulation materials into masonry blocks designed for exterior walls, where VIPs become integrated insulation. This application minimises the hazard of mechanical damage provided the insulation is placed in the block correctly. In this paper, four kinds of materials, applicable as the core of VIPs, are compared. This is a standard mineral wool, commercial VIP based on pyrogenic silica and two experimental types of VIPs based on cotton. Four application possibilities were proposed and thermal properties of individual variants were compared.
Evaluation of Investment Risks in CBA with Monte Carlo Method
(Mendel University in Brno, 2015-03-30) Korytárová, Jana; Pospíšilová, Barbora
Investment decisions are at the core of any development strategy. Economic growth and welfare depend on productive capital, infrastructure, human capital, knowledge, total factor productivity and the quality of institutions. Decision-making process on the selection of suitable projects in the public sector is in some aspects more difficult than in the private sector. Evaluating projects on the basis of their financial profitability, where the basic parameter is the value of the potential profit, can be misleading in these cases. One of the basic objectives of the allocation of public resources is respecting of the 3E principle (Economy, Effectiveness, Efficiency) in their whole life cycle. The life cycle of the investment projects consists of four main phases. The first pre-investment phase is very important for decision-making process whether to accept or reject a public project for its realization. A well-designed feasibility study as well as cost-benefit analysis (CBA) in this phase are important assumptions for future success of the project. A future financial and economical CF which represent the fundamental basis for calculation of economic effectiveness indicators are formed and modelled in these documents. This paper deals with the possibility to calculate the financial and economic efficiency of the public investment projects more accurately by simulation methods used.

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