Selection of heating, ventilating and air conditioning (HVAC) suppliers for green buildings with fuzzy-evaluation based on distance from average solution (EDAS) method

The traditional definiton of successful construction projects were based on completing the project according to budget and expected quality within intended schedule boundaries. However, growing concerns related to environmental issues are shaping tomorrow's definiton of success within environmental boundaries. Intergovernmental aggreements charted new courses in the global climate and environmental effort. Industries are evaluated according to their burden to the nature. According to related-studies, it is found that building industry consumes nearly 40% of total energy use and account for 40% of total global CO2 emissions. This situation obligues the revolutionary changes in the industry. Therefore, new concepts are proliferated. From 1990's green building movement has become increasingly widespread. These buildings are designed and operated to protect environment while considering the life-cycle of every component in them. In order to maintain these approaches, the collaboration of different professions and participants is necessary. It is a fact that consideration of project participants is one of the most vital processes that leading to the success of the projects. Suppliers possess the paramount importance to shape a building because of their strategic role on achieving project aims and protecting competitiveness levels of companies. In order to finish the desired project with success, choosing the right supplier is most of the time the key aspect. Therefore, in green building projects, the selection process have to be followed in the most sensible way within an environmentally-friendly framework. Companies main expectations are shifting towards more sustainable products as well as environmentally-responsible suppliers. A mathematical model is helpful in order to constitute a logic basis for the selection process of suppliers, that should be preferred rather than only personal experiences or instincts. Supplier selection is often studied with the appropriate tools called Multi-criteria decision making methods (MCDM) in order to formulate problems. These methods help professionals in obtaining the most appropriate results according to the pre-defined criteria. In this study, one of the latest MCDM is applied on a green building's HVAC systems supplier selection. Firstly, a broad literature review related to supplier selection, green supplier selection and HVAC systems selection is presented. Also, working principle of HVAC systems is summarized. One of the main components of HVAC systems – air handling units (AHUs) which is used to balance and distribute air as part of the whole, is explained in terms of its contribution to the system. After these, methodology that is used in the study is declared. The definitions of multi criteria and multi attribute decision making is given. Then, Evaluation Based on Distance from Average Solution (EDAS) method is explained within its related formula and logic. In order to describe the Extended Fuzzy-EDAS, information about fuzzy numbers are shown and related equations are given. Fuzzy numbers are applied to the method, because of its ability to comprehensively describe the linguistic environment of real life and successfully translate the vagueness. Fuzzy-EDAS method is described with its equations and mathematical foundation. In the case study, AHUs selection of a green certified shopping center undertaken by a Turkish contractor is processed by Fuzzy-EDAS method is demostrated. HVAC, directly associated to AHU, constitutes one of the most important roles in green building certification and energy consumption levels. The importance of the HVAC related points in the ECOSTANDART certification is given in the study. Therefore, careful selection of the equipment as well as its suppliers is found vital in terms of project success from the literature and the interviews. 8 criteria are identified in order to apprehend the problem in the most comprehensive and leanest way possible. The criteria determined is aimed to set environmental-responsibility; total cost (C1), warranty period (C2), delivery lead time (C3), conformity with specifications (C4), company profile (C5), efficiency level of motors (C6), maintenance and spare parts service (C7) and green production, design and supply (C8). These criteria are shaped along literature review and expert opinion in order to constitute a framework. For the study, bidding files are received and evaluated. Later, 5 experts (between 10 to 40 years of experienced) from the construction and design team evaluated bids of the alternatives according to the criteria developed. After completing the computational process of Fuzzy-EDAS, results have presented the superiority of the second alternative. A sensitivity analysis is also applied to prove that the method is appropriately applicable to the case. Also by that, combination of weights and the preffered alternative's accuracy and righteousness is controlled. A comprehensive literature review is summarized in this study to fully comprehend the related problem. Also, supplier selection, green supplier selection, HVAC systems selection and EDAS method literature is combined and shown in intuitive tables. According to results, the method employed and the criteria has been found satisfactory.