Yapı malzemesi yaşam döngüsü değerlendirmesi-envanter analizi üzerine bir model

Abstract

Yaşam döngüsü değerlendirmesi (YDD) ürün/hizmetlerin üretimden-yok edilmelerine kadar oluşturdukları çevresel etkilerin hesaplanması için geliştirilmiş bir yöntemdir. Dünyada giderek daha yaygın olan YDD çalışmaları kapsamlı çalışmalardır. Bu çalışmalar uygulamada, belirli etki değerlendirme kategorileri açısından ürünleri değerlendiren çevresel ürün beyanlarına (ÇÜB) da dönüştürülmektedir. Dört evreden oluşan YDD içerisinde ikinci evre olan envanter analizi, bu çevresel etkilere sebep olan girdi ve çıktıların nicel olarak derlenmesinin yapıldığı evredir. Dünyadaki uygulamasına baktığımızda farklı ülkelerin, yaşam döngüsü değerlendirmesi amaçlı, yerel ve küresel değerlendirme araçları ve bunlarla ilişkili veri tabanları oluşturdukları görülmektedir. Doğru sonuçlara ulaşan YDD çalışmaları için yerel özellikleri yansıtan ve koşullarla uyumlu araçların ve veri tabanlarının kullanılması önemlidir. Çalışmanın amacı, Türkiye yapı malzemesi sektörü için küresel veri tabanları ile uyumlu bir YDD envanter analizi modeli geliştirilmesidir. Bu çalışma ile Türkiye koşullarını göz önüne alan modelin oluşturulmasıyla, yapı malzemesine dair çevresel etkilerin değerlendirilmesi daha doğru yapılabilecektir. Bu model, yapı malzemesi üreticilerinin çevresel etkisi olumlu malzemesinin öne çıkabilmesine, proje için malzeme seçimi yapacak mimar/mühendislerin daha az çevre etkisine sebep olan malzeme/ürün seçebilmelerine ve genel anlamda çevresel etkisi daha az malzemenin seçilebilmesini kolaylaştırararak ekolojik faydaya hizmet edecektir. Bu çalışma kapsamında YDD ve ÇÜB standartları, YDD yaklaşımları, YDE hesaplama yöntemleri ve seçili veri tabanları incelenmiştir. Veri tabanları seçimi, yapı malzemesine odaklanan YDD veri tabanlarının incelendiği öncül bir çalışmaya dayanır. Bu çalışma kapsamında da incelenen aynı veri tabanları: ecoinvent, GaBi, ELCD/ILCD, Plastics Europe eco-profiles, Athena, US LCI, CPM, Bedec, Probas ve Base Carbone'dur. Bu veri tabanları envanter analizi ile ilişkili temel başlıklar olarak: veri toplanması, veri hesaplanması ve verinin dağıtılması adımları için incelenmiştir. Veri toplanması ile ilişkili alt başlıklar: veri kaynakları, sistem sınırları, işlevsel birim, kapsam kararları, kesim kuralları, elementer akışlar, veri toplanması yöntemi ve veri biriktirilmesidir. Veri hesaplanması ile ilişkili alt başlıklar: eksik verinin tamamlanması, veri kalitesi kontrolü, verinin onaylanması, verinin işlevsel birim ile ilişkilendirilmesi, verinin birim süreç ile ilişkilendirilmesi, verinin kümelendirilmesi ve sistem sınırlarının inceltilmesidir. Bu inceleme sonucunda gözönüne alınan veri tabanları ile olabildiğince uyumlu sınırlar çizilmiş, genel akış şeması oluşturulmuştur. Bu çalışmanın ardından Türkiye yapı malzemesi sektörü için güncel koşullar incelenmiştir. Önceki bölümde oluşturulan akış şemasının Türkiye yapı malzemesi sektörü koşularına göre güncellemesi yapılarak Türkiye yapı malzemesi envanter analizi (TRea) modeli akış diyagramı oluşturulmuştur. Ardından modelin işlerliği alüminyum (Al) yapısal profil üretimi üzerinden incelenmiştir. Çalışmanın sonucunda, Al yapısal profil üzerinden malzemenin sınanmasında, Türkiye'de modern araçlar kullanılarak yapılan çalışmalarda birçok girdi-çıktı verisine ulaşımın olduğu görülmüştür. Buna paralel olarak mevzuat kapsamında da bazı girdi-çıktı verilerinin talep edildiği görülmüştür. Ancak çalışma kapsamının genişletilmesi için gerekli arka plan verilerine dair çalışmaların yapılması gereklidir. Türkiye açısından konu değerlendirildiğinde, envanter analizi akışına dair sektörel abakların oluşturulması ve ölçümlerin sıklaştırılması gereklidir. Çevresel etkilere olumsuz katkısı dolayısıyla özellikle yapı malzemesi sektörü için firma tercihi ile alınan çevresel ürün beyanlarının (ÇÜB) arttırılması gereklidir.

Life cycle assessment (LCA) is a method developed to calculate the environmental impacts of products/services from production to disposal. LCA studies, which are increasingly common in the world, are comprehensive studies. In practice, these studies are transformed into environmental product declarations (EPD) that evaluate products in terms of specific impact assessment categories. Inventory analysis, which is the second stage in the LCA, consists of four stages, is the stage where the quantitative compilation of inputs and outputs that cause these environmental impacts is calculated. When we look at the application in the world, it is seen that different countries have created local and global assessment tools and related databases for life cycle assessment. It is important to use tools and databases that reflect local characteristics and comply with the conditions for LCA studies that reach correct results. The aim of this study is to develop a LCA inventory analysis model compatible with global databases for Turkish building material sector. With this study by the creation of the model considering conditions of Turkey, evaluation of environmental impact of building materials can be made more accurately. It is aimed that the model to be created within the scope of the study will include all building materials. However, in this study, which is the first step of the inventory analysis model, "cradle-to-gate" system boundary and re-cycle were included in the scope. At this stage, the reason for the participation of the re-cycle process, which also has a positive effect on the environmental impact of the materials, is that it is considered as an important process for the correct evaluation of the building materials. This model will serve the ecological benefit by making it easier for building material manufacturers to stand out with positive environmental impact materials, architects/engineers who will choose materials for the project to choose materials/products that cause less environmental impact. Within the scope of this study, literature studies, LCA and EPD standards, LCA approaches, LCA calculation methods and selected databases were examined. In this context, the standards examined in detail are ISO 14040 - Environmental Management series and BS EN 15804 standards. The databases examined within the scope of the study are: ecoinvent, GaBi, ELCD/ILCD, Plastics Europe eco-profiles, Athena, US LCI, CPM, Bedec, Probas and Base Carbone. A previous study on LCA databases about construction materials is used as a base for database selection. These databases were examined as the main headings related to inventory analysis as the main steps in the ISO 14040 series: data collection, data calculation and allocation steps. These steps were detailed by literature and by examining GaBi and ecoinvent documents, which are among the most frequently used LCA databases in the literature. As a result of this elaboration, subheadings related to data collection are: data types, system boundaries, functional/declared unit, scope decisions, cut-off rules, elementary flows, data collection methods and data collection formats. Subheadings related to data calculation are: completing missing data, data quality, data validation, associating data with functional unit, associating data with unit process, aggregating and refining system boundaries. In the study, the rules applied by the analyzed databases for these topics were compiled. Considering these application rules, boundaries are drawn as compatible as possible with the analyzed databases. A base that will provide maximum harmony with the databases evaluated in this way has been created. These rules are also evaluated in the inventory analysis flowchart. This study then examined the current conditions for the sector of building materials in Turkey. Since regulations applied in the production of building materials vary in detail, existing legislation in Turkey is taken into account in general. Turkish building material inventory analysis (TRea) model flow chart is created by updating the flowchart in the previous section according to Turkish building material sector conditions within the context of the headings discussed in Chapter 2 and Chapter 3. After creating the TRea model flow diagram, its operability has been examined over the production of aluminum (Al) structural profiles. Testing of the model by Al structural profile has provided the examination of the model through a material which is energy intensive with recycle process but of which raw material production is limited in Turkey. In testing the TRea model, the inventory analysis in the Al structural profile sample was able to be evaluated within the gate-to-gate (covering only the production process) system boundaries. Within the scope of the study, since the production of a facility producing Al structural profile using ingot Al from abroad was examined, inventory analysis could be done from gate-to-gate. The inventory information included in the cradle-to-gate (raw material production-transportation-material production) system boundary, which is mandatory in BS EN 15804, "raw material production" and "transportation" data must be provided from the raw material manufacturer and the transportation firm within the framework of the flow diagram specified in TRea. In order to obtain consistent data on the production of raw materials, the producer must create this information by applying the same inventory analysis model. If this is not possible, the average data for the same raw material producers in Turkey should be used. To obtain average data TRea model must be applied to various materials and average data must be formed representing conditions of Turkey. Considering the implementation of scope decisions over the Al structural profile, it is seen that it includes energy, water, waste management (including recycling) and on-site transportation. However, data on infrastructure and transportation could not be included. It is possible to include these data by conducting more comprehensive studies. When examining the creation of elementary flow, first it is appropriate to create EPD to collect data on the prior impact assessment categories for Turkish building material. In the Al structural profile sample, it is possible to access some of these data or related data from the site as raw data. However, specially for Turkey, basic required studies of this data must be done (Turkish conditions in electricity production etc.) and formation of necessary databases for this has started. The basic decision in terms of data collection method is to determine the unit processes accordingly and to create and fill in data collection papers according to the required elementary flows. What is needed to be done at this scale is to establish the relationship between elementary flows and impact assessment categories after collecting raw data. In the Al example, the production flow chart at the facility was created and the unit processes for the structural profile were determined. The creation of the flow diagram and the collection of raw data are getting easier and more reliable with the increase in the frequency of recording by the production tools in the sites using modern production techniques. Equipping the production sites with modern tools and making the measurements required in regulations/standards more frequently are issues that will have a positive effect on data collection. By seperation of sectoral product groups, manufacturers with same regulation responsibilities can be formed and data sheets with mandatory data for the product group can be created. For data storage, a comprehensive base required for the TRea database to work together with other analyzed databases should be created. In particular, it is essential that data collection forms must be created from data collection method, elementary flows regarded and concerning data quality indicators (DQIs) in a suitable format. Standart formats are a must for interoperability of databases to allow transformation. Compiling missing data in TRea can be done with the hierarchy created from databases. It is important to create all DQIs of the analyzed databases, both in terms of ensuring compatibility with other databases and being used as part of the internal review mechanism. Internal validation methods can also be used in the approval process. In the Al structural profile example, the responsiveness of the DQIs in the analyzed databases at the facility was evaluated. At the end of this study, it was seen that all necessary indicators can be answered. In the Trea model, which is a scientific study covering different disciplines, university approval is recommended as external approval. During the collection of data in the model, it is recommended not to do aggregation, which is the gathering of equivalent data. There is no data to be aggregated in the Al example. In the transfer of information from inventory analysis to the impact assessment stage, aggregation can be done with the necessary mathematical operations by selecting the appropriate clusters from the stored data. In the Al structural profile example, no mathematical operations for aggregation are done, but it is possible in the model to aggregate if needed. In the Trea model, it was suggested that the allocation should be done according to physical and then economic balances. In the Al structural profile example, allocation could be made by physical relations without using economic relations. The control of allocation should be done by applying the 100% rule, as recommended in the ISO 14040 standard series. When TRea, which is an inventory analysis model for Turkey's building material sector, is evaluated over Al structural profiles, it is seen that the model has an applicable flow. However, inventory analysis, a comprehensive study area supported by databases, is closely related to the following issues; creation of other databases related to Turkey, reduction of labor-intensive process of studies, execution with Turkey's conditions. Similarly, with the evaluation of different materials in the model, a building material database associated with TRea will also be created. Creation of this database will facilitate the implementation of the background database and will support studies to reflect the characteristics of Turkey. Modelling raw data-elementary flow-impact assessment categories of TRea model, must have a priority in the establishment of database containing background data of Turkey's conditions. LCA inventory analysis is a process that can be easily accelerated by adapting regulations in Turkey. However, in this evaluation method, where the measurement frequency is important for reliability, reducing the economic values of the measurements and increasing the measurement frequency with laws/regulations will make a positive contribution to data quality. In this way, the creation of the TRea inventory database can be done quickly and reliably, with the required data coming from the sector within the framework of certain standards. Advancing the analysis from cradle-to-cradle boundary is necessary to complete the "life cycle" concept. For this, in the TRea model, the boundaries that include cradle-to-gate and recycling must be completed by adding transportation, construction, use and renovation phases. In addition, necessary studies should be done for a database that will work in harmony with the TRea model flow diagram. The creation of the abaca to collect inventory data related to building material sector conditions in Turkey and intensification of measurements are neccessary. Due to the negative contribution of building material production to environmental impacts, it is necessary to increase the use of environmental product declarations (EPDs) which are received by the company preference currently. Cooperation of building material sector, universities and governmental agencies for this purpose, can accelerate number of building material EPDs.