Vesna Žegarac Leskovar

Energy-Efficient Timber-Glass Houses

The introductory chapter sets a background frame and reveals the main reasons which encouraged the authors into researching the topic of energy efficiency of buildings. Section 1.2 is a brief overview of the authors’ activities in the fields of energy efficiency and timber-glass construction, while Sect. 1.3 shortly outlines the content of the book. 1.1 Why Dealing with the Topic of Timber-Glass Buildings? Climate changes of the last few decades do not only encourage researches into the origins of their onset, but they also mean a warning and an urgent call for a need to remove their causes and alleviate the consequences affecting the environment. Construction is, besides the fields of transport and industry, one of the main users of the prime energy from fossil sources, which makes this sector highly responsible for the implementation of climate-environmental policies. Activities linked to energy efficiency and the related use of renewable sources of energy are not infrequent in Slovenia, nevertheless, the fields of architecture and construction still offer numerous possibilities of reaching the goals set by directives on energy efficiency in buildings. Looking for alternative, eco-friendly solutions in residential and public building construction remains our most vital task, whose holistic problem solving requires knowledge integration. The present book represents merely a piece in the jigsaw of different kinds of knowledge that will need to undergo mutual integration and upgrading in order to be used in designing an optimal energy-efficient timber-glass building. The current work can be useful to designers and future experts in their planning of optimal energy-efficient timber-glass buildings. The study is based on using timber and glass which used to be rather neglected as construction materials in certain historical periods. Nevertheless, timber achieved recognition as one of the V. Zegarac Leskovar and M. Premrov, Energy-Efficient Timber-Glass Houses, Green Energy and Technology, DOI: 10.1007/978-1-4471-5511-9_1, Springer-Verlag London 2013 1 oldest building materials in different countries worldwide. With the appearance of cast and wrought iron in the eighteenth century along with the subsequent use of reinforced concrete and steel in the twentieth century, which all enabled mass production and construction of larger structural spans, timber lost its dominance as a building material McLeod [1]. Only in recent decades has timber been rediscovered, partly due to the contemporary manufacture of prefabricated timber elements and partly owing to high environmental potential of this renewable natural building material. Although glass has been used to enclose space for nearly two millennia, the roots of modern glass construction reach back to the nineteenth century green houses in England, witnessing one of the first instances of using glass as a loadbearing structural element in combination with the iron skeleton, Wurm [2]. Throughout the twentieth century, glass was no longer used as load-bearing element, but rather as an aesthetic element of the building skin with strongly emphasized potential of transparency enabling natural lighting and visual contact of the interior and exterior space. In contrast to the listed positive properties, glass used to be treated as the weakest point of the building envelope from the thermal point of view. Dynamic evolution of the glazing in the last 40 years resulted in insulating glass products with highly improved physical and strength properties, suitable for application in contemporary energy-efficient buildings, not only as material responsible for solar gains and daylighting, but also as a component of structural resisting elements. With suitable technological development and appropriate use, timber and glass are nowadays becoming essential construction materials as far as the energy efficiency is concerned. Their combined use is extremely complicated, from both the constructional point of view as well as from that of energy efficiency and sets multiple traps for designers. Moreover, a novelty value of modern glass is seen in its being treated as a load-bearing material replacing the elements (diagonal elements, sheathing boards) which normally provide horizontal stability of timber structures. A good knowledge of advantages and drawbacks of timber-glass structures is thus vitally important. 1.2 Authors’ Work in the Field of Energy Efficiency and Timber-Glass Construction Within a selection of most important issues, our activities in the frames of the University of Maribor, Faculty of Civil Engineering, focus primarily on research work and its application into practice, on educating students and the broader public (Fig. 1.1). Our scientific work in the field of energy efficiency of the buildings concentrates on researching design models of energy-efficient timber-glass buildings, which combines the knowledge of architecture, timber-glass construction and building physics. We strive to link the findings of our research work with practice 2

Design Approach for the Optimal Model of an Energy-Efficient Timber Building with Enlarged Glazing Surface on the South Façade

Abstract This paper presents the reasonability of using an increased proportion of glazing surfaces in prefabricated timber-frame buildings with a special focus on energy efficiency by using an enlarged glazing area in the south façade. The research is based on a case study of a two-storey house built in a prefabricated timber-frame structural system taking the climate data for Ljubljana into consideration. Parametric analysis is performed on the variation of an increased proportion of the glazing surfaces impact in the south side of the building according to the total surface of the south façade (AGAW) as a basic variable. The analysis was carried out on different exterior wall elements having different thermal properties, while the rest of the parameters, such as the ground plan of the model as well as the active systems, roof and floor slab assemblies, climate condition, etc. remain constant. The basic theoretical contribution of the presented research is the transformation of a complex energy related problem to only one single independent variable (Uwall-value) which becomes the only variable parameter to determine the optimal glazing area size value (AGAWopt) for all contemporary prefabricated timber construction systems.

Timber-Glass Prefabricated Buildings

This chapter is based on using timber and glass which were formerly rather neglected as construction materials. With suitable technological development and appropriate use, they are nowadays becoming essential construction materials as far as energy efficiency is concerned. Their combined use is extremely complicated, from the energy efficiency perspective presented in Sect. 4.3 on the one hand and from the structural viewpoint presented in Sect. 4.4 on the other, which sets multiple traps for designers. A good knowledge of their advantages and drawbacks is thus vitally important, as will be seen in the first two sections of the current chapter. The results of the comparative analysis contained in the last two sections can serve as a good frame of reference to architects and civil engineers in their approximate estimation of the energy demands emerging from different positions and proportions of the glazing surfaces, in addition to being of assistance in their assessment of the influence of the building shape exerts on the energy demand of prefabricated timber-frame buildings.

Strengthening of timber floors with CLT panels – a numerical study

The purpose of this article is to provide an insight into the field of timber floor strengthening with cross-laminated timber (CLT) panels. A classic

Structural Systems of Timber Buildings

The current chapter presents a set of main aspects of timber building with a focus on timber-frame constructions. A brief description of timber’s material characteristics in Sect. 3.1 aims at getting acquainted with potential advantages and disadvantages of planning and designing timber buildings, in comparison with using other structural materials, such as concrete or masonry. Section 3.2 discusses predominantly used structural systems of timber construction along with the most important structural and technological characteristics and possibilities. Section 3.3 describes computational models and methods, with their limitations and application in practice. The influence of the sheathing material and the openings studied in our previous numerical and experimental research is additionally shortly presented in order to provide a better insight into a rather problematic area of applying the glazing to timber buildings, which is the main contents part of Chap. 4. Multi-storey prefabricated timber building is one of the increasing opportunities for the public, commercial and residential sectors in the future. Stability problems appearing due to heavy horizontal actions along with possible strengthening solutions already applied in practice are the topic of Sect. 3.4.

Energy-Efficient Building Design

The current chapter discusses a number of important aspects whose influence on the energy efficiency of new buildings calls for their careful consideration as early as in the design phase. With the basics of energy-efficient building design figuring in Sect. 2.1, the next important topic contained in Sect. 2.2 deals with commonly used classification systems determining the energy efficiency level of buildings. In order to understand energy-efficient design principles, basic facts on energy flows in buildings are given in Sect. 2.3. The relation between the building design, climatic influences and the building site analysis can be found in Sect. 2.4. Section 2.5 introduces a set of main design parameters, such as orientation, shape of the building, zoning of interior spaces and the building components. Description of the building components focuses mainly on those composing the building thermal envelope, with glazing surfaces and timber construction being only briefly presented, while a more detailed specification of the two materials follows in Chaps. 3 and 4. For the complexity of energy-efficient design, passive design strategies comprising passive solar heating, cooling, ventilation and daylighting are considered in Sect. 2.6. Finally, Sect. 2.7 provides an overview of the role of active technical systems, since they have become an indispensable constituent element of contemporary energy-efficient houses.