Jan Pasek

Probabilistic assessment of failure risk of the building envelope thermally insulated from the inside

Abstract Thermal insulation of external walls is designed in particular to reduce energy performance of buildings. Insulation placed on the outer side of walls act as an effective protection against the external environment. On the contrary placing the thermal insulation layer on the inner side of the building envelope is quite hazardous as the internal insulation does not fulfil the protective function. It actually exposes the bearing layer of the building envelope to the immediate effect of the environment and therefore it enhances the negative impacts of the cyclic temperature changes on structural system of the building. This paper focuses on probability risk of development of failures on such construction depending on variable boundary conditions (rigidity of the structure, strength of the materials, and range of the temperature load). Besides this there is also comparison of probability and deterministic approach to the evaluation of static reliability of the building constructions. Using of probabilistic approach in this context is still very rare. The aim of this paper is to analyse the effects of internal insulation on load bearing system of buildings, and to verify the applicability of probabilistic methods in the analysis of structural reliability. Like the deterministic approach, it draws attention to the high risk of failure of the structures insulated from the inside. At the same time, however, it shows the high demands of the probabilistic method on the amount of input data. If the data are not available, it is possible to replace some of them results of deterministic method; this approach has negative consequences in mutual dependency of accuracy of achieved results.

Impact of Internal Thermal Insulation Systems on Static Behaviour of Exterior Walls

In general, in the climatic conditions of the Czech Republic the inner insulation of cladding structures is an unsuitable solution to reduce heat loss of building by means of heat transfer. This statement is valid both in terms of building thermal techniques and also in terms of statics. Research focused on the hygrothermal regime of external walls insulated on the inside is very extensive. On the other hand, the systematic attention is not yet paid to detailed analysis of the consequences of such solution on the static behavior of the cladding structures. The paper focuses on analysis and evaluation of stress increase in external walls and adjacent structures caused by non-forced effects of temperature changes in the environment after the application of internal insulation.

The Specifics of the Real Estate Market of the Low- and Passive Energy Buildings

Real estate appraisal based on market principles is the science that is directly linked to market economy and should adequately respond to current and the changing needs of both direct real estate market, as well as banking, construction and also legislation and state and local administration. One of the current market requirements is the issue of fair valuation of low- and passive energy buildings in conditions where the market for this type of property is just taking off. This paper describes the most important principles of energy-efficient buildings appraisal, evaluates the motivational incentives for the development of this segment of real estate market and predicts its future development potential.

Economic Analysis of Energy Saving Measures in Current Prefabricated Panel Buildings

The paper focuses on analysis and assessment of economic effectivity of measures taken in order to lower energy demands of prefabricated panel residential buildings. For this purpose, a group of buildings with previously made modifications with potential to lower the energy and heating consumption were selected. Next, the development of their energy consumption and their costs was monitored. The assessment of achieved figures was made with regards to amount of costs which were paid for these measures and also with regards to their service life, amount of gained subsidy and decrease of consumed energies and operational costs of the buildings after the measures were taken. It was found that there had been a significant difference in investment returns for constituent technical measures. For some of them, it is not even realistic to expect reaching the return of investments during their service life period.

The Operational and Environmental Consequences of the Polystyrene Insulation Disposal

In connection with the significant volume of polystyrene embedded in buildings as thermal insulation, in the next few years it will be needed to solve the matter of its disposal after the end of its life cycle. Hexabromocyclododecane (HBCDD) has been used as a flame retardant in polystyrene thermal insulation (EPS and XPS) for the last 50 years. The internationally recognized Stockholm Convention on Persistent Organic Pollutants prohibits future production, use and recycling of materials that contain HBCDD. It also, to a large extent, limits the options of waste management of such materials. European legislation, in particular Regulation (EC) No 850/2004 and the so called REACH Directive, established a binding legal framework for EU Member States which reduces waste management options of material containing HCDBB practically only to incineration. In the coming years, this fact requests fundamental changes in disposal of construction and demolition waste containing the polystyrene insulation and related processes on construction sites in the Czech Republic. The research is based on the analysis of the international and the Czech legislation related to this issue, and the analysis of material and technological context. The paper focuses on possible operational, economic, energy and environmental impact on the construction industry and environment, and compares the current situation in the Czech Republic with other European countries, and assesses the readiness of the Czech Republic to deal with the upcoming legislation changes.

Numerical simulations of the influence of temperature changes on structural integrity of stone temples in Angkor, Cambodia

Modelling the static behaviour of representative structures of stone temples in Angkor.Investigating the response of structures on the load of temperature changes.Investigating the causes of the process of collapse of stone structures.Newly developed models will be used for analysis of remediation procedures of monuments. Mediaeval stone temples on archaeological site Angkor were built between 9th and 14th century. Ever since they have been exposed to many external detrimental effects of various intensity. Among others, significant are temperature changes causing specific character of failures of the structures. These are caused by partly irreversible and in time increasing cyclical micro-movements of individual stone blocks. The total sum of all movements happening since their creation in these risk areas reached values high enough to cause stone blocks falling out of the structures. Process of cyclical shrinking and expansion of stone structures represents significant contribution to their total disintegration. This text presents preparation and progress of numerical simulations of static behaviour and process of disintegration of stone temples caused by the influence of temperature changes. It introduces a principle of creation and optimization of numerical models for construction and load put on them including preparation of all input data and evaluation of the achieved results. The analysis of static reliability of the stone temples is performed in the framework of activities of Czech National Project at Angkor (CNPA). Theoretical simulation of structural behaviour of the stone temples in Angkor presents a unique approach as nothing similar has been attempted before.

Interior Environment of the Buildings Hit by Floods

Deterioration of the quality of interior environment is always consequence of buildings being hit by floods. The structures and the furnishing of the buildings are exposed during such event to moisture and contaminants carried by the floodwater. Comprehensive evaluation of the effects of floods on buildings is very difficult due to influence of large number of factors, which may be mixed in infinite number of varieties. This paper is focused on analyses of the most important factors influencing the quality of the interior environment of the buildings when flooded the characteristics of the building structures, furnishing and floodwater.

Impact of Façade Colouring on Temperature and Light Conditions of Buildings, Housing Estates, and Environment

Design of the color solution of the façade is usually focused only to achieve subjectively desirable aesthetic look of the building. In the whole context it however has many other connections including the environmental one. From this point of view it is very inappropriate to use dark colors with high absorption of solar and diffused radiation. This paper is focused on the influence of the color of the façade surface on the external and internal surface temperature of the external walls, temperature of the air in their surroundings, and day lighting of the interior.

The Influence of Colour Solution of the ETICS Surface on its Thermal Exposition

The colour solution of the surface of the façade is one of the basic factors for reaching the requested aesthetic and architectonic expression of the building. This target is sometimes reached by using very saturated tones of colours or changing dark and light tones on one façade. Such solution is often risky as one of the characteristics of dark colour tones is high absorption of solar and scattered radiation. Its thermal compound causes warming of the outer layers of the façade proportionally to the surface colour saturation. This consequence is very serious especially for thin-layer plaster of external thermal insulation composite systems (ETICS) immediately exposed to dynamic effect of external environment temperature changes, which can be even increased by inappropriate colour solution of the ETICS surface. This paper focuses on evaluation of the influence of ETICS surface colouring on the thermal load.