Advanced Materials Research Vol. 899

Abstract: According to the recast of the European Directive on the Energy Performance of Buildings Member States shall ensure that (a) by 31 December 2020, all new buildings are nearly zero-energy buildings; and (b) after 31 December 2018, new buildings occupied and owned by public authorities are nearly zero-energy buildings. It is the responsibility of the Member States to define the measure of nearly. This paper analyses the challenges of setting the requirements. In order to ensure that the requirements are realistic, they should be checked on reference buildings. The statistical evaluation of a large building sample as reference is recommended instead of using a few typical case studies. The potential and obstacles of various renewable energy sources are analysed for favourably located buildings and for buildings in urban areas, where solar access and space may be limited. Urban buildings will be able to comply with the requirements only if energy production from renewables on a district or urban scale (off-site) is realized and acknowledged in the energy balance. A case study of apartment buildings shows the future importance of the ratio of the energy collecting surface to the floor area.

Abstract: The paper deals with the distribution temperature fields of soils at a real building object. These temperature fields are based on continuous (2 years worth of) measurements of temperature in certain depths of soils at a building structure. When designing buildings the climatic data are applied for a specific area only. Albeit in case of soils temperature the data are rather general, all locations do have the same values. One factor that significantly affects the soil temperature, are the thermal parameters inside and outside of buildings. The soils temperature is affected considerably by the structural solution used on a building, particularly in areas where thermal insulation is in contact with structures and the ground too. Whereas in case of soils there are no coherent outputs of temperatures with dependence to the characteristics of external and internal environment as much as to the structural solution of a building, the main aim of the paper is to make an impulse for the creation of comprehensive temperature data packs for soils for predetermined depths, structures and parameters of indoor and outdoor environment.

Abstract: Energy demand reduction in buildings is an important measure to achieve climate change mitigation. It is essential to minimize heat losses in designing phase in accordance of building energy efficiency. For building energy efficiency in a mild climate zone, a large part of the heating demand is caused by transmission losses through the building envelope. Building envelopes with high thermal resistance are typical for low-energy buildings in general. In this sense thermal bridges impact increases by using of greater thickness of thermal insulation. This paper is focused on thermal bridges minimizing through typical system details in buildings. The impact of thermal bridges was studied by comparative calculations for a case study of building with different amounts of thermal insulation. The calculated results represent a percentage distribution of heat loss through typical building components in correlation of various thicknesses of their thermal insulations.

Abstract: Building envelopes with high thermal resistance are typical for low-energy buildings. Detailed specification and calculation of each thermal bridge in these buildings should be taken into account. This paper is focused on thermal bridges minimizing through typical window systems in building envelopes. The aim of this article is to analyze the window position influence, as regards on thermal performance and to point out the installation modality in accordance with the characterization of the windows performance. This can be done by quantifying the percentage increment of the window jamb thermal transmittance. The calculated results also demonstrate that there is significant difference between results obtained by various available calculation approaches. This can be significant especially in buildings with high thermal protection.

Abstract: This contribution presents the results of a long-term thermal comfort monitoring effort in the so-called OEKOHAUS building in Petronell, Lower Austria. This building mainly acts as an educational facility for the Museum of Natural History of Vienna and includes also office and short-term occupancy spaces. It was established in an existing building, adapted and refurbished in 1996. At the time of refurbishment, it clearly exceeded the applicable standard thermal requirements for building elements. Given the building's unique mixed use, it displays a highly fluctuating occupancy pattern. Subsequent to the recent installment of energy and indoor climate monitoring system, multiple streams of data are being collected. Specifically, indoor environmental variables relevant to thermal comfort in a number of zones in the building have been monitored and evaluated. Collected data include indoor temperature and relative humidity, which were represented and analyzed for different zones of the building in terms of psychrometric charts (for a monitoring period in Winter 2012/13). Moreover, indoor CO₂ concentration was monitored to address indoor air quality conditions. The paper presents the monitoring results and their meaning within the larger context of a monitoring-based holistic building performance assessment strategy.

Abstract: Occasionally, there are suggestions from professional public to use the total solar energy transmittance coefficient, g (solar factor), to describe not only transparent, but also opaque structures, particularly with regard to overheating of the under-roof spaces. The standard EN 410:1998 (Glass in building - Determination of luminous and solar characteristics of glazing) introduces the g-value as the sum of primary solar heat gain, g₁, due to the transparency of the glazing and the secondary solar heat gain, g₂, due to the absorption of solar radiation and its conversion into heat conduction and radiation over the total incident solar heat flux, φ_e. Nevertheless the value of g₁ may have zero or nearly zero value, e.g. in case of non-transparent glass. In addition to it, the standard ISO 15099:2003 (Thermal performance of windows, doors and shading devices - Detailed calculations) introduces equation for calculation of the frame g-value (actually the frame total solar energy transmittance), where window frames are clearly opaque components. What is then the difference between glass and "standard" opaque wall or roof Why is in the latter case always introduced zero and in the first one some value different from zero Won't it be practical, especially in time of large existing opportunities of computer use, to implement the use of g-values also in case of ordinary opaque structures and express their resistance to the absorption and conversion of solar radiation and thus overheating the adjacent interior spaces This paper attempts, using EN ISO 13786 (Thermal performance of building components - Dynamic thermal characteristics - Calculation methods) and computer-aided models of transient heat transfer, to explain why the suggestion of using of the g-value in case of opaque components is not entirely correct and, why priority should be given to the dynamic thermal characteristics specified in this standard.

Abstract: Nowadays, the perspective of city hotels in the competition with the rivals that are successful mixed-use, commercial, social and leisure centers which take hotel the clients, is in their revitalization. Especially older hotels nowadays are almost empty. The reason is simple: they have mostly monofunctional character and they are unable to respond flexibly to the increasing demands of clients. Not only the function, but also the space quality is not developing fast enough to compete with the requirements and trends in the sphere of tourism. Within the revitalization of the existing hotel substances, it is necessary by the use of modern technology to react to environmental considerations. These aspects, for various reasons, whether spatial or technical, cannot always be applied by the reconstruction of objects. This paper devotes to the rules and principles that are essential for the energy efficiency of revitalized hotels. It defines the critical determinants and criteria when creating new spaces based on the efficient use of resources, the ecological principles and the principles of using intelligent technologies. The paper examines simultaneously the impact on their architectural quality, whereas urban hotel has often a very exposed position in the urban areas.

Abstract: As energy efficiency is becoming an increasingly important feature, buildings are expected to comply with several criteria and requirements and these criteria are changed and extended with time. The Directive 2002/91/EC of the European Parliament and Commission on the energy performance of buildings and the Directive 2010/31/EU request Member States to apply minimum energy performance requirements. These minimum requirements are indeed applied all over the European Union and should be regularly reviewed. Our research aimed at clarifying whether optimum cost and/or energy efficiency represents the next step towards actual energy efficiency. The Directive brought forth an aspect that should have been prioritized long ago already: Are the construction and refurbishment of buildings in Europe economically feasible The methodology prescribed by the Directive leaves several questions open and provokes further research. The methodology uses costs only as the basis for examining energy consumption and emissions related to already existing, newly constructed or refurbished buildings or refurbishment options. Optimum cost does not necessarily correspond to optimum energy or environmental performance. The price of materials and equipment built in does not always reflect the energy built in or environmental advantages. Subsidies to promote energy efficiency may bias optimum costs. Viewing optimums from the broader aspect of energy consumption, proper results are only yielded by analyses completed for the entire life cycle of buildings. This way, we may decide which characteristics attribute more to a low energy and emission status, i.e. state-of-the-art construction technology or traditional, natural constructing methods such as those used for „conservative eco buildings.” [1]

Abstract: Recent national and international building regulations on the energy performance of buildings focus mainly on the reduction of operational energy. This can be achieved by increasing the energy efficiency of the building, installing highly efficient building service systems and applying renewable energy sources. However, these measures have a price in terms of investment costs, and also in terms of environmental impacts. The life-cycle of building materials, building constructions or whole buildings from cradle to grave can be assessed using the method of Life Cycle Assessment (LCA) and Life Cycle Cost analysis (LCC). These tools take into account not only the heating energy saving due to additional insulation, but also the embodied environmental impacts and costs of the investment. In this paper, the optimum thickness of various insulation materials, including natural and recycled materials is examined considering three main environmental indicators and global costs. The analysis is performed for a typical Hungarian single-family house subject to retrofit.

Abstract: Building sector plays an important role in climate impacts mitigation, as it is responsible for 40% of global energy use and global GHG emissions. Climate change has a dual implication on the built environment: on one hand human settlements and buildings are vulnerable to the effects of changing climate and on the other hand the building sector has a significant climate change mitigation potential. Although nowadays the trends are positive, the share of newly built low-energy buildings is very low, the near-zero-energy building market is in its early phase. Simultaneously the optimizing technologies in the building design are strongly highlighted. The presence of the energy and environment efficient buildings and the stringent building energy regulations of the EU need more accurate building design. The constant design parameters will come to foreground and their role will be appreciated. The relevant sustainable development and building policies, as well as the building design, construction and maintenance should jointly respond both to adaptation to and mitigation of climate change. This paper focuses the relevance of the main constant design parameter: How to take into account the increasing outdoor temperature in the building energy design.