Environmental Impact Classification Utilizing Activity-based LCA Model of XPS Insulation System Manufacturing Phase

Transcription

1 Environmental Impact Classification Utilizing Activity-based LCA Model of XPS Insulation System Manufacturing Phase Abstract: In response to worldwide efforts to reduce global warming gases, the construction industry has endeavored to diminish carbon dioxide emission. Especially, by introducing the LCA methodology to the industry, a variety of studies related to measuring of emission of carbon dioxide have been conducted. When the conventional LCA methodology is applied to the construction project, however, some limitations have been reported. To overcome the restrictions derived from the characteristics of this industry, this research suggested the Activity-based LCA model by applying the Activity-based Costing(ABC), which breaks down the whole life cycles into more detailed stages. By implementing the newly developed model, forecasting accuracy of CO 2 emission was elevated and the critical control point on carbon dioxide were established. Through the reviewing of XPS insulation system at manufacturing phase, this research verified the usefulness of the Activity-based LCA. Key words: Activity-based LCA, Activity-based Costing, Environmental Cost, CO 2 Emmision 1. Introduction Recently, people s understanding and concern about rapid global warming has been on the rise. As a result, there have been strenuous efforts to reduce environmental impact factors (ex: CO 2, etc.) which accelerate global warming in construction industry as well. In particular, studies relating to the development of Life Cycle Inventory (LCI) database and evaluation programs have been actively performed in order to introduce LCA methodology which investigates the emissions of environmental impact factors from the life cycle perspective to construction industry. At application of the current LCA to construction industry, however, there are limitations in handling a large number of construction materials. Furthermore, it is not easy to use the analysis results as an environmental impact management tool from the life cycle perspective in construction industry. In addition, because the existing LCI database contains raw material-related database only such as electricity, concrete and steel, there is not enough time to develop LCI database to assess the LCA in construction projects in which a wide variety of materials are used. To overcome these barriers, this study reduced the necessity to specify the life cycle in construction industry with a goal of improving the usefulness of LCA methodology and assessing composite materials by combining the already existing database. In this study, therefore, an activity-based LCA model in which cost is specified using the activity-based cost management method was proposed. This model classifies the activity-based life cycle into specific processes and enables the monitoring of the results of the environmental impact assessment by stage. Then, the conventional raw material-based LCI database was combined with the materials which are supplied by activity to make the environmental impact assessment of the analysis subject easy. This study aims to identify problems of LCA methodology applied in construction area through review on existing studies and to point out the limitation of introduction and utilization. As it is deemed 1

2 necessary to have subdivided LCA methodology for application in construction area in the future, this study presents Activity-based LCA model, deriving from ABC cost management skill. 2. Consideration on Existing Study 2-1. LCA methodology-related studies in construction industry Unlike the manufacturing industry in which an LCA is commonly introduced for an environment impact assessment, construction industry has a significant long life cycle with a huge amount of input and output. Therefore, there have been difficulties in developing and analyzing the LCI database. Korea Institute of Construction Technology developed LCI database on construction materials and developed the related assessment program titled KLCA [1]. However, because the database failed to handle all materials used in the construction project, there has been a doubt on its effectiveness. The results of the LCA analysis would be used for comparison of alternative. Weiland performed an LCA to compare Portland Cement Concrete (PCC) and Hot Mix Asphalt (HMA) for replacement of road pavement of I-5 in the U.S[2]. In addition, Lee compared alternatives in management methods to reduce the level of environment impact in the maintenance stage by carrying out the LCA of sewage treatment recycling facilities[3]. As mentioned above, there is a high possibility that current LA-based studies in construction industry in which a great number of materials are used would be available as just a tool for numerical comparison of alternatives. Therefore, it appears that they would not be used as a management tool to reduce the emission of environment impact factors ABC Cost Management System Conventional cost management system allocates the cost based on production output or working hours and is a suitable type when direct labor cost takes high percentage in total production. However, in the today s production system that is represented as mechanization, automation, production process innovation and small quantity batch production, the percentage of direct labor cost reduced and indirect cost including fixed cost related to equipment considerably increased. Accordingly, it was pointed out that dependence on traditional cost management type might result in distortion of price and further, establishment of wrong management strategy [4]. Cost management system for this purpose is ABC cost management system. ABC cost management system separates function of company into Activity per feature for calculation of accurate cost, collects the costs per activity using this as the target of basic cost management, applies resource driver and activity driver which are the criteria of allocation and allocates the costs to the products. Here, Activity is the work of creating value using resources and is defined as the basic analysis unit of generating cost and concrete case or transaction that consumes resources in the process of product production of company. Activity is largely divided into 1) Unit-level 2

3 activity, 2) Batch-level activity, 3) Product-level activity, and 4) Facility-level activity. Unit level activity is performed whenever one unit of product is produced in proportion to product production. Batch-level activity is the activity performed in the unit of batch and includes purchase, procurement activity, sample quality examination activity and work preparation activity. Product level activity is the activity that is performed to keep the product line and includes maintenance activity, environment cleaning activity and safety management activity[5].to distribute the activity into the unit cost of product in ABC, it passes through 5 stages from Resource Resource Driver Activity- Activity Driver Object. Through this process, it became possible to accurately identify the cost generated in activity, to distribute this to cost and to perform reasonable cost estimation Studies relating to the allocation of ABC cost management method-based environmental cost and environmental management ABC Cost Management System is the type that subdivides the environmental factors and imposes environment cost to production cost and is utilized as the tool of environment management[6]. The reason why ABC cost management system is utilized in environment cost analysis can be summarized into 2. It is because ABC identifies the activity, resource consumed for that activity, resource driver showing casual relationship of resource consumption, product from consumption of activity, and activity driver, which is the casual relationship for activity consumption. In addition, it is because ABC enables to perform cost analysis even if analysis is not performed since it classifies for analysis of activity related to environment among various activities generated in the production of products[7]. In addition, ABC cost management system was not only used for estimating environment cost, but also utilized as the tools for environment management. Chen stratified the management system and constructed activity based management system by relating this to environment activity[8], and Emblemsvag constructed environment management model focusing on resource and energy cost utilizing ABC and identified the activity with excessive environment costs through simulation[6]. In this regard, this study recognized the necessary of stages subdivided than life cycle so as to represent the complicated structure of construction industry. For this purpose, this study utilized the activity of ABC cost management type as the plan for estimating environment cost in order to subdivided the life cycle, and aims to construct Activity-based LCA model using the system of classifying the activity into the process of subdividing the life cycle of LCA. 3. Activity-based LCA Model 3-1. Concept of Activity-based LCA Model Products from construction area have the life cycle stages of 1) Material collection and processing, 2) Material production, 3) Construction, 4) Maintenance and 5) Removal and 3

4 Dismantling. In addition, transportation stage occurs as it passes through each life cycle stage. Activity-based LCA model applies and analyzes Activity concept focusing on life cycle stage of construction area. It identifies the emission and factors per activity by classifying the activity per type through process analysis of each stage of life cycle and analyzing the CO 2 emission of activity. That is, by performing LCA analysis per activity unit and measuring emission of CO 2 based on this, it identifies the causes through analysis of emission point and utilize this to allocation of environment cost (Image 1) [4]. Imagen 1 Activity-based LCA Model Diagram[4] 3-2. Features of Activity One of feature that differentiates activity-based LCA model from existing LCA model is that it prepares the inventory in the activity unit. Construction industry is based on the process and the boundary of process is clear so that there are clear criteria for designating the process as activity. Accordingly, it seems easy to apply activity-based LCA model that focuses on process. The data for utilization and classification of stage performed in inventory analysis of LCA methodology are detailed inventory such as resource and energy input and output (level 3) and life cycle (level 1). However, this study analyzed the detailed process of life cycle stage and designated the activity (level 2) for analysis of CO 2 emission, and based on this, aims to draw up input and output inventory. Like the definition on activity of ABC above, Activity of Activity-based LCA model can classify the process that performs the similar works into same activity through detailed process analysis. At this point, the value in environment management perspective, the standard of activity classification, means the environmental value, the data that can be used for environmental impact analysis including output materials in LCA analysis or input like resource or energy(jam Emblemsvag, 2001). In this regard, this study merged the processes which have similar environmental impact emission factor of similar process and classified them into same activity in order to satisfy the goal of constructing management system of Activity-based LCA in construction area. It is possible to classify activity by applying the criteria which are deemed easy to perform 4

5 including selection of management point and establishment of management instruction according to purpose of utilization, in addition to classification standard of activity presented in this study Criteria for Classification of Activity Activity established by environmental impact factor in the construction area focusing on feature of activity analyzed above can be deduced in consideration of 1) resource input, 2) energy use and 3) degree and type of environmental impact. In this study, activity will be classified and named 1) Direct Activity (DA), 2) Indirect Activity (IA), 3)Changeable Activity (CA), 4) Non-Impact Activity (NA), according to the emission type of substance that affects the environment. Direct Activity is the activity that has direct environmental impact due to use of energy or input of resource in the area of construction. Indirect Activity refers to the output of substance that has indirect impact on environment through activities such as design, order, reception and quality inspection. That is, if there is energy or resource that are used for maintenance aspect of factory, while there is no input of resource of energy, that activity can be selected as indirect activity. Changeable Activity refers to the activity in which the amount of input/output material in function unit according to the project, such as transportation. In this regard, Changeable Activity should calculate the input/output for each project by tracing the transportation process of materials even if products are produced in same factory. Non-impact Activity is the activity that does not emit any factor that affects the environment through activity and includes rest time and standby time Activity Designation of XPS Insulation System at Manufacturing Phase To designate the activity of XPS insulation system, detailed process was analyzed throughout the life cycle of manufacturing phase. Activity was classified according to the environmental effect, the activity driver focusing on the detailed process analyzed. Classified activity are designated as 4 types of activity and impact ratio, and, the impact ratio comes from experts investigation(table 1). Table 1 XPS Insulation System Activity of Manufacturing Phase Level 1 (Life Cycle) Level 2 (Activity) Activity Type Impact Ratio Mixing Direct Activity 0.03 Melting Direct Activity 0.15 Extruding Direct Activity 0.23 Manufacturing Loading and Transportation Cooling Direct Activity 0.10 Forming Direct Activity st Cutting Direct Activity nd Cutting Direct Activity 0.12 Packing Indirect Activity 0.04 Loading Direct Activity / Indirect Activity 0.08 Transportation Changeable Activity

6 4. Conclusion The introduction of an LCA in construction industry follows a global trend to reduce the emission of environmental impact substances. Because of high demands for the introduction of the LCA, therefore, there have been a lot of studies such as construction material LCI database development & assessment program, and many of them have been actually developed and implemented. Even so, use of a lot of materials and equipment and long life cycle have been obstacles in the promotion of the LCA in construction industry. Therefore, it s been necessary to adjust the LCA analysis method to facilitate the introduction of LCA and use it as a management tool. With this perspective, this study proposed activity-based LCA under the ABC cost management method for the environmental impact assessment and analysis focusing on life cycle in the conventional LCA. This study conducted an activity-based LCA analysis on the activities in the XPS insulation system of manufacturing phase only. In further studies, therefore, it is required to expand the scope of analysis to cover all activities and perform a study based on empirical data in all lifecycle stages. Reference 1. Korea Institute of Construction Technology (2003) Unit Requirement DB and Programe Development for the LCA of Buildings. Seoul. MOLT. 2. Craig Weiland (2008). Life-cycle Assessment of I-5 Pavement Replacement. University of Washington Research Report. 3. Lee, Shin-won et al. (2011) Life-Cycle Assessment (LCA) for Eco-Design in a Wastewater Reuse Facility. J Korean Soc Civ Eng, vol.31(2): , ISSN: /KCI. 4. Lim, Ji Youn et al. (2012) Implementing Activity-based LCA Model for Carbon Dioxide Emission Analysis and Allocation of Environment Cost The case study of Curtain Wall System. KJCEM, Vol. 13(4):78-88, ISSN: /KCI. 5. Song, Sang-Hyup (2010) IFRS Cost Managment Accounting. Seoul. Woongji, Inc. 6. Jan Emblemsvag (2000) Activity-based Cost and Environmental Management: A Differnet Approach to the ISO Compliance. Kluwer Academic Publisher, Inc. 7. Yuk, Keun-Ho (2009) Environment Management Accounting Theological and Practical Practice. JipMoonDang, Inc. 8. F. Frank Chen (1996) Activity-based approach to justification of advanced factor management system, Industrial Management & Systems. 6