The evaluation of environmental sustainability in the context of operational and embodied energy on exterior wall, examples of hotel buildings from Istanbul

External walls are the first subject examined in this thesis about the evaluation of environmental sustainability in the context of operational and embodied energy. In the literature review study on the concept of exterior wall, revealed that the building, which is the most exposed to the outdoor conditions of the building, is the most important element of the building and is big part of the building envelope. Due to the high increase in energy consumption and the negative effects of this consumption on the world, the energy consumption in the buildings and the sustainable building feature can be provided by the external walls which fulfill the various performance requirements. Therefore, the aim of this study is evaluating the environmental sustainability of the external walls in operational and embodied energy in hotel buildings examples from İstanbul. The thesis is consisted of; the introduction which includes the definition, purpose, hypothesis, scope and methodology, three main chapters and conclusion and evaluation chapter. At the beginning of the work, the definition of the problem has been revealed depending on such factors as increasing population, developing technology, increasing energy consumption, sustainability, reasons for the emergence of sustainability, environmental sustainability, high user comfort expectation in buildings with the increase of construction technology, the effect of external walls on user comfort. The aim is to evaluate the external walls that cover up a large part of the building envelope in terms of operational and embodied energy according to environmental sustainability criteria from Istanbul through hotel building samples, to determine operational and embodied carbon dioxide values and to create proposals for more sustainable design of buildings in the design phase. "Environmental sustainability in the external walls of buildings is not used as a multi-dimensional design input. Only the size of the operational energy is taken into account, the embodied energy size can be neglected." This expression constitute the hypothesis of the study. Istanbul is a geopolitical location with a high importance and a landmark in terms of cultural, commercial and tourism. This constitutes the geographical scope of the work. In the typological study, hotel buildings with priority and user needs and comfort were selected. Due to the fact that the subject of the study is the most discussed subject in architecture, the temporal scope has been revealed as modern buildings. The foundations, walls, floors, roofs, columns, staircases and windows, each of which have a distinct and important function, are the main elements of the building. The exterior walls, which are the most exposed elements of the building to the outer environment, are covered in this study. External walls have been evaluated over environmental sustainability, which has become more important in recent years. In additon, İstanbul is a country which has over twenty million inhabitants in daytime. The city is constantly developing and old buildings are being renewed. Old industrial and business areas of İstanbul has been changed into service-oriented areas. The buildings which are related to service-oriented areas are increasing. This variety provides a new identity for İstanbul in terms of architectural design, exterior wall systems, selection of materials and building elements that creates a big potential about performance based architectural researchs. In the study, high-end hotel buildings from İstanbul have been selected. These buildings are reflecting creative architectural visualization and satisfying user comfort requirements. The methodology consists of the selection of key words, book review, national thesis centers review, international articles / papers with electronic databases review, topic designation, specific books / articles / papers review related to the subject, example selection study, evaluation and proposals for the implementation. In the second part of the study, the concept of the exterior wall which constitutes a large part of the building envelope the historical development and classification of the exterior walls are explained. Performance on the exterior walls was examined in 6 headings and the section was finalized. In the third chapter, the relationship of environmental sustainability and external wall were analyzed. For this reason, the concept of sustainability and environmental issues are taken under the title. Under this heading, sustainability concept, basic principles, types, environmental sustainability and the process of emergence of environmental assessment are mentioned. Then, the importance of environmental sustainability in the building life cycle and energy use, the energy from the production of materials on the exterior walls (embobied energy), the effect of the external walls on the usage process expenditure (operational energy) and finally the evaluation of environmental sustainability on the exterior walls were explained. Assessing environmental sustainability is a comprehensive issue. One of the method of assessing environmental sustainability is LCA (Life Cycle Assessment). LCA addresses the environmental aspects and potential environmental impacts (e.g. use of resources and environmental consequences of releases) throughout a product's life cycle from raw material acquisition through production, use, end-of-life treatment, recycling and final disposal (i.e. cradle-to-grave). Lifecycle emissions resulting from buildings consist of two components: operational and embodied emissions. A great deal of effort has been put into reducing operational energy as it is assumed that it is higher than embodied energy. However, studies have revealed the growing significance of embodied emissions on buildings but its importance is often underestimated in lifecycle emissions analysis. Therefore, this paper has been considered appropriate to evaluate environmental sustainability in the context of operational and embodied energy on the external walls of different hotel buildings. In the case study section which constitutes the fourth part of the study, firstly the purpose and method are given, then the information obtained from the architecture offices of the 5 hotels selected from Istanbul and the exterior wall details are presented, the u value of the external wall details, the annual heating energy and the amount of CO2 resulting and the embedded carbon dioxide amounts were calculated. In the evaluation section, data obtained from the field study were obtained, inferences were made, and the operational and buried carbon dioxide amounts of the exterior wall details and details of the hotels were compared. In the conclusion section, the study was finalized by introducing some suggestions to the designers in addition to the inferences resulting from the evaluation of the hotels in the previous section and by providing some information that can be taken as reference.