Activity-based life cycle analysis of a curtain wall supply for reducing its environmental impact

Activity-based life cycle analysis of a curtain wall supply for reducing its environmental impact

Accepted Manuscript Title: Activity-Based Life Cycle Analysis of a Curtain Wall Supply for Reducing its Environmental Impact Author: June-Seong Yi Yon...

613KB Sizes 0 Downloads 7 Views

Accepted Manuscript Title: Activity-Based Life Cycle Analysis of a Curtain Wall Supply for Reducing its Environmental Impact Author: June-Seong Yi Yong-Woo Kim Ji Youn Lim Jeehee Lee PII: DOI: Reference:

S0378-7788(16)31715-7 http://dx.doi.org/doi:10.1016/j.enbuild.2016.11.061 ENB 7176

To appear in:

ENB

Received date: Revised date: Accepted date:

9-5-2016 17-11-2016 28-11-2016

Please cite this article as: June-Seong Yi, Yong-Woo Kim, Ji Youn Lim, Jeehee Lee, Activity-Based Life Cycle Analysis of a Curtain Wall Supply for Reducing its Environmental Impact, Energy and Buildings http://dx.doi.org/10.1016/j.enbuild.2016.11.061 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Title: Activity-Based Life Cycle Analysis of a Curtain Wall Supply for Reducing its Environmental Impact June-Seong Yi1, Ph.D. Professor, Yong-Woo Kim2*, Ph.D.Associate Professor, Ji Youn Lim3, M.S., Jeehee Lee4, M.S. Ph.D. Student, 1

Department of Architectural Engineering, Ewha Womens University Department of Construction Management, University of Washington 3 Korea Institute of Civil Engineering and Building Technology 4 Department of Architectural Engineering, Ewha Womens University 2

*

Corresponding Author

1

Highlights  This paper suggests Activity-based LCA (ABLCA) adopting a process mapping tool.  The study extends LCA to an environmental management tool for managerial purposes.  The study applied the proposed ABLCA to the curtain wall supply chain process. Life-Cycle Assessment has been used extensively in the construction industry to assess the environmental impacts of building materials. Attributional LCA considers processes in a supply chain which allows users to identify a process to improve to minimize the environmental impacts. However, the level of detail adopted in traditional attributional LCA is aggregate, not appropriate for process improvement efforts in the construction project context which is characterized as a complex system. This paper proposes Activity-based LCA (ABLCA) which adopts the methodology of the activity-based costing system to carry out the assessment and analysis of environmental impacts for the life cycle. The research carried out a case study on the curtain wall supply chain. The outcome of inventory analysis for each activity and environmental impact assessment showed the curtain wall supply chain process made an impact on five environmental impact categories: global warming air, acidification air, HH criteria air; eutrophication air, and photochemical smog air. With comparison to the outcome of environmental impact assessment from existing LCA, the proposed management system to investigate environmental impacts was addressed. The proposed ABLCA enables management to develop an environmental-impacts-reduction plan focusing on critical activities.

Keywords: Attributional LCA (Life-Cycle Assessment), activity-based management, Environmental impacts, activity-based management, curtain wall 1. Introduction 1.1 Background and Motivation As efforts to reduce environmental impacts such as global warming gases, the construction industry endeavors to estimate and temper carbon dioxides emissions through product and process design. The growing body of literature on environmental impacts on construction projects evinces the importance of the issue [1-8]. For instance, Cole [2] identified the importance of issues such as sustainability, life-cycle assessment, globalization and standardization. Crawley and Aho [3] discussed the potential market applications of environmental impact assessment methods and compared several of the major environmental assessment methods. In this regard, various attempts have been made to evaluate the environmental impacts associated with construction materials and methods [9-14]. Most studies thus far have focused on life-cycle impacts of specific building materials. The current Life Cycle Analysis (LCA) in the construction industry focuses on input and output associated with major construction materials such as steel or concrete in bills of materials (BOM). While environmental impact analysis using LCA is being used in material selection, it is not fully employed in process improvement efforts. Though attributional LCA considers processes in a supply chain which allows users to identify a process to improve to minimize the environmental impacts, the level of detail adopted in traditional attributional LCA is aggregate, thereby not appropriate for process improvement efforts in the construction project context which is characterized as a complex system 1.2 Purpose The goal of this research is to propose a revised attributional LCA that can be used in the construction supply chain where LCA can be employed for process control, which enables users

2

to monitor and control the impacts of each process on environments. To this end, this paper proposes employing activity-based management and process modeling to leverage LCA technique taking into accounts environmental impacts. The paper also reports the results of a case study where a proposed methodology was applied to the curtain wall supply chain. This paper seeks to measure direct and indirect lifecycle greenhouse emission of curtain wall supply chain using activity-based costing based life cycle assessment which allows users to provide environmental impact information to process and operational management. In our study, a process-based attributional Life Cycle Assessment (LCA) method with activity-based management was applied to a curtain wall supply chain. 2. Related Works LCA is a systematic approach to assess where, and in what form, resources and energy are consumed and transferred to emission and/or waste throughout the life cycle of a product or system [15]. The life cycle of a building usually spans the acquiring and procurement of construction materials, construction processes, operation and maintenance, and demolition. LCA can be implemented in either attributional LCA or consequential LCA [15]. Consequential LCA considers environmental impacts associated with the life cycle of specific product as well as the indirect effects on surrounding systems [16]. Consequential LCA expands the scope of LCA to a larger system that includes system boundaries as well as systems that are connected to the system boundaries. As far as the subject of this study is concerned, consequential LCA of the glass curtain wall (CW) systems would additionally address the indirect environmental impacts of surrounding systems such as electricity supply and demand system. It is noted, however, significant uncertainties of surrounding systems would have impact on the results of a consequential LCA study. On the other hand, attributional LCA is a method of conceptualizing the life cycle of a materials or processes within a system boundary [17]. A model is developed through identifying processes that are used to fabricate a product and tracking the inputs and outputs for each process in attributional LCA [15,17]. In attributional process-based LCA, the model is generated with inputs (e.g., natural resources and energy) and outputs (e.g., emissions/waste) in each unit process throughout a product life cycle [17]. The results are aggregated to acquire the environmental inputs and outputs for the product or material over its whole life cycle. In most cases, LCA has been applied in construction projects to select alternative materials in a product design process taking into account their environmental impacts. Weiland [18] made a comparative analysis on two alternate paving materials on Interstate-5: Portland Cement Concrete (PCC) and Hot Mix Asphalt (HMA) using LCA.. Minne et al. [19] made an environmental and economic LCA study of renovating window options for 17 climate zones in the US. Kim and Bae [20] presented the results of a case study on the environmental impacts of lean delivery strategy of rebar supply (i.e., prefabrication and pull-driven delivery) on a highrise condominium project. Azari and Kim [21] investigated how change of mullion materials in curtain wall (CW) systems would have impact on health and environments using LCA. LCA have been applied to present specific criteria such as environment responsibility and social behavior to be applied by supply chain agents based on the environmental impact. Dadhich et al., [22] investigated the direct and indirect lifecycle greenhouse gas emissions of the plasterboard supply chain of a leading European distributor of building materials with the help of a hybrid LCA technique. Albino et al. [23] proposed economic, energy and environmental interactions in order to support the analysis of materials and energy flows among the production processes of supply chains. Though attributional LCA addresses processes in a supply chain, the level of details in process analysis is aggregate, not appropriate for process improvement efforts such as process reengineering. For example, the unit of process in traditional attributional ABC does not match with the unit of activity in process control to which resources (e.g., costs) are assigned. The

3

current attributional process-based LCA does not allow for process improvement study in the construction supply chain being characterized as a complex system since process improvement needs data that provides users with the impacts of the changes in each process on environments. This study, though adopting attibutional LCA methodology, proposes using activity-based management tool in which processes can be decomposed into detail activities to which resources can be assigned when needed. 3. Research Method: Activity-Based Life Cycle Assessment 3.1 Concepts and Characteristics of ABLCA In a previous section, literature on life-cycle assessment suggested that current methods of life-cycle assessment revealed shortcomings in using LCA as a process management or process improvement tool. Emblemsvåg [24] proposed applying activity-based costing to LCA, in which energy drivers and associated energy consumption intensities are traced to each activity for environmental assessments. Fig. 1 shows a diagram that depicts a process of assessment in which assigning energy and environmental input to each activity on which CO2 footprints are calculated. Distinct from conventional life-cycle assessment, activity-based life LCA develops life cycle inventory on each activity in the activity list. Traditional LCA uses one-staged allocation where environmental input and output such as energy are allocated to each stage of life cycle. On the other hand, activity-based LCA uses two-staged allocation where environmental input and output are allocated to activities, which are then allocated to each stage of life cycle [25]. However, Emblemsvåg and Bras [25] still used activities at the aggregate level, which prevents users from using the data in process improvement efforts. This study adopts a process map to identify activities on which resources and environmental input are allocated. The process of ABLCA employed in this research is shown in Fig. 2. This research extends the scope of ABLCA to the function of process management. The study classifies activities into five levels: least sensitive, less sensitive, normal, sensitive, most sensitive. The activities are classified based on the adjusted value1 of their environmental impacts using the following criteria:  Above 80 percentile: Most Sensitive  60 ~ 80 percentile: Sensitive  40 ~ 60 percentile: Normal  20 ~ 40 percentile: Less Sensitive  Below 20 percentile: Least Sensitive 3.2 Standard and Designation of Activity Categories of Curtain Wall System To measure the environmental impacts the activities can be developed by comprehensively considering the following: 1) input of resource, 2) usage of energy, and 3) the level and type of environmental impacts. In this research, the activities deduced from each method of emission of environmental substance are categorized as the following; 1) Direct Activity (DA), 2) Indirect Activity (IA), 3) Changeable Activity (CA), and 4) Non-Impact Activity (NA). ‘Direct activity’ refers to those that directly affect the environment in the construction field with inputs of resource or uses of energy. ‘Indirect activity’ refers to the activity of emitting indirectly 1

The study used exponential growth function for its classification due to the values of environmental impacts of each activity showing immense variability. 4

affecting substances such as design works, ordering, receiving orders and quality checks. In other words, even if a direct input of resource or energy doesn’t occur, if there is energy or a resource used during operation of the factory, the activity can be configured as an indirect activity. ‘Changeable activity’ refers to activity that varies the amount of input/output substance in production units according to each project such as shipping. Here, changeable activity should include input/output substances for each construction site by tracking down the transportation of the raw material even if the substances are produced in the same factory. ‘Non-impact activity’ includes activity that does not emit substances that affect the environment. In order to establish activities of the curtain wall system, a detailed process was analyzed for the total life cycle. On the analysis of the detailed process, activities were categorized according to environmental factors which are ‘activity drivers’. Categorized activities are divided into 4 types of activities and these types were coded to increase their utilities Table 1. 4. Case Description and Conditions of Analysis 4.1 Purpose and Scope of Activity-based LCA This research intended to measure the emission of environmental effects for each activities of the curtain wall (CW) system and to understand the activities which designate future management positions by implementing an activity-based LCA. In particular, this research applies to cases on unit-type CW systems which are mostly factory produced, to decrease uncertainties during the field installation for more effective utility of activity-based LCA. 4.2 Case Description The analysis of activity-based LCA suggested in this research was carried out in a high-rise residential building project located in Seoul, Korea. The size of project is 109,707 m2 in gross area and there are 4 buildings with 9 stories below ground and 27 – 35 stories. The construction period was total of 52 months from September 2009 to January 2013. The production amount of materials and the information of inputs/outputs for the curtain wall system were collected from the manufacturing factory of the specialty contractor in charge of production and delivery. The production factory is located in Ko-yang city, Gyeoung-gi province, Korea, and is approximately 25 km apart from the construction site. 4.3 Analysis Conditions The reproducibility of research and reliability of outcome in the LCA analysis can be improved if the implementation conditions are clearly defined. Therefore, the study intended to clarify the size, shipping distance, recycle ratio of curtain wall system which may vary in characteristics for each construction project to increase the reproducibility and reliability. In addition, the research carried out a direct observation on the production and assembly of materials focusing on production amount during May to October 2011 as well as on operating hours and downtime of the equipment from June to November 2011. 4.3.1 Curtain Wall System Because curtain wall systems are generally customized to each site conditions, it is hard to generalize the standard size of curtain wall systems. Therefore, systems with the most common types and sizes among curtain wall systems used in the case were applied. Here, a simple unit type curtain wall system with 1200 mm x 3200 mm in size, 160 mm thickness and 24 mm tempered double-glazing was used in the research. The unit weight of the curtain wall system is

5

approximately 100 kg excluding the glass and approximately 150 kg with the glass. 4.3.2 Transport The distance between the manufacturing factory and the construction site is about 25km. The transport route uses local roads on a 5-ton diesel truck. Each truck can load 4 pallets and each pallet can transport 4 – 5 sets of curtain wall units. In summary, the maximum load for a 5-ton truck is 16 – 20 sets of curtain wall units. 4.3.3 Maintaining and Dissolution Unit type CW systems generally have less defect cases due to infrequent field installations. Also, because the completion of the case project is relatively recent, the actual data of maintaining and dissolution stage could not be applied. For this matter, based on the opinions from professionals from installation and production businesses, the repair was assumed to be carried out on 5% of the total installation amount of the CW system. According to the Korea Waste Association (2010)’s landfill, incineration and recycle ratio of waste classification, 95% of waste aluminum and 60% of waste glass were recycled as scrap process, and the rest of the waste materials were buried in the landfill. As the activities of maintaining and dissolution stages occur after the project completion, the estimation value was calculated by applying the Eq. (1). Ek (kWh) = Pk × Wk × Ok

(1)

Ek :

the energy consumption of Activity using equipment k (kWh)

Pk :

the energy output of equipment k (kW)

Wk :

Total operating time of equipment k (hr)

Ok :

Utilization rate of equipment k assigned on Activity

5. Activity-based LCA Analysis of Curtain Wall System 5.1 Configuring System Boundaries Based on the activities (Table 1) from the detailed process of the life cycle analyzed in Section 3.3, the system boundaries of Activity-based LCA (ABLCA) analysis was configured focusing on ‘changeable activities’. For ‘indirect activities’ such as manpower, facility management and orders, as values can differ by difference in labor and deterioration of facilities, these were excluded from the target of this research. Also, as the stage of ‘raw material gathering and manufacturing’ is reflected in the stage of ‘material production and assembling’ when applying previously established LCI (Life Cycle Inventory) DB (Database), it was excluded from the target of this research. From the stages of ‘dissolution’ and ‘maintaining’, as the case project has only recently been completed, actual data couldn’t be obtained. Instead, it was substituted by estimation. The system boundaries of this research configured with process map showing functional flow of input material and energy source in the curtain wall supply chain are as shown in the shaded part of Fig. 3. 5.2 Inventory Analysis 5.2.1 Inventory Analysis of Inputs

6

To carry out the inventory analysis for each activity, the total production amount and total energy consumption of the CW system were investigated. In addition, energy consumption for equipment was measured taking into consideration the operating ratio of the equipment for each activity,. Normally, for curtain wall systems, the amount is calculated based on weight (kg). However, in this research, each element of the curtain wall system is recognized as a unit to calculate the LCI DB and LCI was formed on the activities included in the unit so that it satisfies the purpose of the Activity-based LCA. Therefore, as shown in Eq. (2), the categorized production weight (Wb, Wp, Wg, Wz) is divided by the unit weight (Wu, 151.4 kg) to calculate the total production quantity (Eu) as shown in Table 2. Eu = (Wb+Wp+Wg+Wz) / Wu

(2)

The energy consumption was distributed and calculated from the usage of electricity and fuel considering the operating ratio of equipment used for each activity. The total energy consumption evaluated from this method is shown in Table 3. As the energy consumption for each unit was assigned by the operation ratio of equipment for each activity, the value was obtained by dividing the total number of produced units into the energy consumption. When an identical material is used by multiple activities to produce one part, the consumption of the material is evenly distributed for all activities. The input list of resource and energy for each activity of the curtain wall system calculated in this manner is shown in Table 3.

5.2.2 Inventory Analysis of Outputs The inventory analysis of outputs was analyzed based on that of inputs for each activity. To perform the inventory analysis of outputs, the LCI DB of input resources and energy is advised to apply the national or regional DB according to the ISO14040 Series. Therefore, this research utilized the DB developed in Korea for the LCI DB for resource and energy of the activity. The inventory analysis for each activity referred to the aluminum extruded bar, aluminized sheet, plate glass and galvanized sheet iron from the material section of the relevant LCI DB, and fuel and electricity are referenced for the energy section. The emission amounts of major substances (such as CO2, CO, CH4, NOx, N2O, SO2, Sox, and VOC) were measured to assess the impact level for each environmental impact category. The inventory analysis of outputs for each activity is depicted in Table 4.

5.3 Impact Assessment of Curtain Wall System In this section, the environmental impacts on each activity of the curtain wall system were assessed. Outputs were classified by the environmental impact category, and characterization was implemented to calculate the weighting factors in the relevant category. 5.3.1 Classification In this research, the environmental effects of the curtain wall system was assessed based on the environmental impact categories configured by TRACI (Tool for the Reduction & Assessment of Chemical and other environmental Impacts); Global Warming Air, CO2-eq/kg, Acidification Air, H+moleseq/kg, Human Health Cancer Air, benzene-eq/kg, Human Health Non-cancer Air, toluene-eq/kg,

7

Human Health Criteria Air, milli-DALYs/kg, Eutrophication Air, N-eq/kg, Ozone Depletion Air, CFC-11-eq/kg, Eco-toxicity Air, 2,4-D-eq/kg, and Photochemical Smog Air, gNOx-eq/g. The inventory analysis of outputs from the case study showed that the curtain wall supply chain process made an impact on five categories out of nine environmental impact categories as shown in Fig. 4. 5.3.2 Characterization In the ‘characterization’ phase, all the outputs were translated under the same standard. The relative indices provided from IPCC (Intergovernmental Panel on Climate Change) and TRACI were applied in this research, and the relationship between outputs and the environmental effects in the case study is described in Fig. 5. The value of characterization in the relevant environmental impact category can be obtained by multiplying the weighting factors of the above categories and each representative output. The standard output is displayed by affixing ‘-eq (-equal)’. The value of characterization for the case study of CW system is shown in Table 5 below.

5.3.3 Interpretation of Activity-based LCA After comprehensive analysis on the environmental impact on the curtain wall system using the Activity-based LCA (ABLCA) model suggested in this research, the assessment results of the aluminum extrusion bar cutting activity (B11) and aluminum extrusion bar processing activity (B12) were overwhelmingly higher than other activities from the manufacturing and assembly stages of the material. The environmental impacts of material manufacturing and assembly were higher in the order of aluminum sheet punching (B21), aluminum sheet bending (B22), glass cutting (B31), glass tempering (B32) and glass double-glazing (B33). And environmental impacts of the installation stage were higher in the order of lifting (D13) and installation (D14). In conclusion, it was recognized that the amount of emission rapidly increases during the activities of processing the raw materials of aluminum curtain wall including aluminum extrusion bar, aluminum sheet and 24 mm tempered double-glazing. The assessment of environmental impacts for each category was presented in a graph to explain the level of environmental impact for each activity. Fig. 6 below shows an example of the category of ‘Photochemical Smog Air’. 6. Environmental Impact Management System using ABLCA The outcome of environmental impacts assessment derived in Section 5 shows a significant deviation for each activity. Therefore, in this section, the outcome value of environmental impact assessment was adjusted to provide an effective management system using ABLCA. The environmental impact on each category was divided into 5 levels, and critical management points have been selected for the purpose of an efficient utilization of the ABLCA model. 6.1 Categorization of Activity The ABLCA model suggested in this research developed an environmental management system based on the environmental impact category, and divided each activity into 5 levels in

8

the order of ‘Most Sensitive, Sensitive, Normal, Less Sensitive and Least Sensitive’. The outcome of the impact assessment was logged to adjust the value as shown in Table 6. It is ‘Most Sensitive’ if the adjusted value of environmental impact category is in the top 20%, ‘Sensitive’ for top 20% - 40%, ‘Normal’ for top 40% - 60%, Less Sensitive for top 60% - 80% and ‘Least Sensitive’ for low 20%. For each environmental impact category, all activities were classified according to the adjusted value as shown in Table 7. 6.2 Development of Management System using ABLCA In order to build a management system for environmental impact using ABLCA, three stages (1st management point, 2nd management point and continuous management point) of critical management points according to effectiveness based on the process map (Fig. 3) of the curtain wall system were selected. ‘1st management point’ included activities with the ‘Most Sensitive’ level from environmental impact assessment. More urgent improvement should be suggested to decrease environmental impact on the activities classified as ‘1st management point’. ‘2nd management point’ included activities with the ‘Sensitive’ level from the impact assessment. If additional measures to decrease environmental impact are required, this point can be considered along with ‘1st management point’. ‘Continuous management point’ included activities with the ‘Normal’ level. These classified activities are not high on the environmental impacts, but these points should be consistently observed to prevent any increase in emission amount. Based on the critical management points selected in this manner, a decision maker can establish an efficient management plan for each environmental category. For an exemplary case, category of ‘Photochemical Smog Air’ is shown in Fig. 7. 7. Discussions The proposed ABLCA method can be an effective means in evaluating life cycle emissions of construction supply chain coupled with process / operational study. Existing LCA implements an environmental impact assessment for life cycle stages. In other words, it analyzes inputs and outputs for each life cycle stage and carries out an environmental impact assessment. The summary is presented in Table 8 below. The outcome of the environmental impact assessment from the existing LCA model showed an overwhelmingly high value of ‘raw material gathering and manufacturing’ stage in all environmental impact categories. The next highest value was in the ‘construction’ stage. Also, the ‘maintaining’ stage showed the least environmental effect. On the ‘global warming’ category, the value from the ‘dissolution’ stage was higher than that of the ‘transportation’ stage, but other environmental impact categories showed a higher value from the ‘transportation’ stage Table 8. When the outcome of an existing LCA model in Table 8 is compared to the detailed analysis of activity-based LCA model in Section 5.3.3, the utilization is clearly differentiated. For example, from the impact category of ‘Photochemical Smog Air’, the existing LCA showed a higher environmental impact in the order of ‘production and assembly > construction (installation) > transportation > dissolution > maintaining’. However, in the ABLCA model, it was found that the transportation activity (C11) contributed higher environmental impact factors compared to ‘aluminum sheet painting’ (B23) , ‘curtain wall assembly’ (B41), ‘shipment’ (B44) and ‘carry in on-site’ activity (D11). In the existing LCA, the ‘production and assembly’ stage showed an overwhelmingly higher value in all environmental impact categories compared to other life cycle stages. However, in

9

the ABLCA, critical management points differ according to each detailed activities. This information was not given from an existing LCA outcome, and this not only allows more segmented reasons for emission of pollutants but also suggests clear grounds for establishing improvement measures to decrease environmental impacts. Also, when environmental costs are charged under the existing analysis of LCA, environmental costs can be concentrated simply on the ‘production and assembly’ stage. However, when using Activity-based LCA, environmental cost can be reasonably distributed into activities which cause environmental effects, enabling a more effective production management. 8. Conclusion The application of LCA in the construction industry is in line with the global movement to decrease emission of environmental impacts. Though related researches on LCA of building materials have been implemented, varied input materials and equipment as well as long life cycle were obstacles in vitalization of LCA application in the construction industry. With awareness on this matter, this paper suggests Activity-based LCA (ABLCA) which adopts the ‘activity’ concept in the ABC cost accounting method to carry out assessment and analysis of environmental impacts for the life cycle. This paper proposes Activity-based LCA (ABLCA) which adopts the methodology of the activity-based costing system to carry out the assessment and analysis of environmental impacts for the life cycle. The research carried out a case study on the curtain wall supply chain. The outcome of inventory analysis for each activity and environmental impact assessment showed the curtain wall supply chain process made an impact on five environmental impact categories: global warming air, acidification air, HH criteria air; eutrophication air, and photochemical smog air. The study also extended LCA to include an environmental management tool, which uses a process map. The process map has five categories classified by emission amounts: most sensitive, sensitive, normal, less sensitive, and least sensitive. The most significant finding in this study emerged from detailed analysis on production process. While the existing LCA model analyzed the environmental impacts based on six life cycle stages, the ABLCA included more detailed analysis based on the process map which included 28 activities. The outcome of the environmental impact assessment from the existing LCA showed an overwhelmingly high value in ‘production & assembly’ stage in all environmental impact categories. The next highest value was in the ‘construction’ stage. The results from ABLCA show that activity C11 (transportation) contributed higher environmental impact factors than activities B23 (aluminum sheet painting), B41 (curtain-wall assembly), B44 (shipment), and D11 (carry in on-site). The proposed method allows a project manager or environmental manager to work with a construction manager in charge of process management to reduce environmental impacts of activities which are classified as critical. The research shows how ABLCA can be implemented and suggests how the results can be leveraged for managerial purposes assuming stakeholders involved in a supply chain are cooperative. It is noted, however, that the use of ABLCA outcomes can be challenging in managing construction supply chains where multiple entities are involved, each of which has its own commercial interests. In future research, the issue of implementation, i.e., how ABLCA results can be leveraged for managerial purposes, needs to be investigated. The implementation issue also includes (1) aligning interests among project stakeholders and (2) integrating ABLCA results with traditional activity data (e.g., costs and schedule). Acknowledgements This work was supported by the National Research Foundation of Korea’s Grant funded by the Korean Government (NRF-2013008723) and UW (University of Washington)'s P. D. Koon Endowed Funds.

10

References [1] Straut, J. (1993). Greener Building–Environmental Impact of Property: The Macmillan Press Ltd. England. [2] Cole, R. J. (1998). Emerging trends in building environmental assessment methods. Building Research & Information, 26(1), 3-16. doi: 10.1080/096132198370065 [3] Crawley, D., & Aho, I. (1999). Building environmental assessment methods: applications and development trends. Building Research & Information, 27(4-5), 300-308. [4] Rees, W. E. (1999). The built environment and the ecosphere: a global perspective. Building Research & Information, 27(4-5), 206-220. [5] Cooper, I. (1999). Which focus for building assessment methods–environmental performance or sustainability? Building Research & Information, 27(4-5), 321-331. [6] Junnila, S. and A. Horvath (2003). Life-Cycle Environmental Effects of an Office Building. Journal of Infrastructure Systems, 9(4), 157-166. [7] Junnila, S., et al. (2006). Life-Cycle Assessment of Office Buildings in Europe and the United States. Journal of Infrastructure Systems, 12(1), 10-17. [8] Lizana, J., Barrios-Padura, Á., Molina-Huelva, M., & Chacartegui, R. (2016). Multi-criteria assessment for the effective decision management in residential energy retrofitting. Energy and Buildings, 129, 284-307. doi:http://dx.doi.org/10.1016/j.enbuild.2016.07.043 [9] Bilec, M., Ries, R., Matthews, H. S., & Sharrard, A. L. (2006). Example of a hybrid life-cycle assessment of construction processes. Journal of Infrastructure Systems, 12(4), 207-215. [10] Zhang, Z., Wu, X., Yang, X., & Zhu, Y. (2006). BEPAS—a life cycle building environmental performance assessment model. Building and Environment, 41(5), 669-675. doi: http://dx.doi.org/10.1016/j.buildenv.2005.02.028 [11] Bribián, I. Z., Uson, A. A., & Scarpellini, S. (2009). Life cycle assessment in buildings: State-of-theart and simplified LCA methodology as a complement for building certification. Building and Environment, 44(12), 2510-2520. [12] Kellenberger, D., & Althaus, H.-J. (2009). Relevance of simplifications in LCA of building components. Building and Environment, 44(4), 818-825. doi: http://dx.doi.org/10.1016/j.buildenv.2008.06.002 [13] Azari, R. (2014). Integrated energy and environmental life cycle assessment of office building envelopes. Energy and Buildings, 82, 156-162. doi: http://dx.doi.org/10.1016/j.enbuild.2014.06.041 [14] Kim, K.-H. (2011). A comparative life cycle assessment of a transparent composite façade system and a glass curtain wall system. Energy and Buildings, 43(12), 3436-3445. doi:http://dx.doi.org/10.1016/j.enbuild.2011.09.006 [15] Curran MA (1996). Environmental life cycle assessment. US: McGraw Hill. [16] Andrae, A. S. (2009). Global life cycle impact assessments of material shifts: the example of a leadfree electronics industry: Springer Science & Business Media. [17] Initiative, U.-S. L. C. (2009). Guidelines for social life cycle assessment of products. United Nations Environment Programme. ISBN, 978-992. [18] Craig Weiland (2008). Life-cycle assessment of I-5 pavement replacement. University of Washington

11

research report. [19] Minne, E., Wingrove, K., & Crittenden, J. C. (2015). Influence of climate on the environmental and economic life cycle assessments of window options in the United States. Energy and Buildings, 102, 293-306. doi:http://dx.doi.org/10.1016/j.enbuild.2015.05.039 [20] Kim, Y.-W., & Bae, J. (2010). Assessing the environmental impacts of a lean supply system: Case study of high-rise condominium construction in Korea. Journal of Architectural Engineering, 16(4), 144-150. [21] Azari-N, R., & Kim, Y.-W. (2012). Comparative assessment of life cycle impacts of curtain wall mullions. Building and Environment, 48, 135-145. [22] Dadhich, P., Genovese, A., Kumar, N., & Acquaye, A. (2014). Developing sustainable supply chains in the UK construction industry: A case study. International Journal of Production Economics. [23] Albino, V., Izzo, C., & Kühtz, S. (2002). Input–output models for the analysis of a local/global supply chain. International Journal of Production Economics, 78(2), 119-131. doi: http://dx.doi.org/10.1016/S0925-5273(01)00216-X [24] Emblemsvåg, J. (2001). Activity-based life-cycle costing. Managerial Auditing Journal, 16(1), 17-27. [25] Emblemsvåg, J. and Bras, B. (2000). Activity-Based Cost and Environmental Management: A Different Approach to the ISO 14000 Compliance. Kluwer Academic Publishers.

12

Fig 1 . Process Diagram of Activity-Based Life Cycle Assessment

Fig. 2. Activity-Based Life-Cycle Assessment (ABLCA)

13

Fig. 3. Process Map with System Boundary of CW System

Fig. 4. Classification of Environmental Impact Category

14

Fig. 5. Weighting Factors of Environmental Impact Category

Fig. 6. Environmental Impact on ‘Photochemical Smog Air’ category

15

Fig. 7. Activity Map for Environmental Impact Management (Photochemical Smog Air)

16

Fig. 8. Comparison of Impact Assessment between LCA & ABLCA (Photochemical Smog Air)

17

Table 1. Activities of Curtain Wall (C/W) System level 1

level 2

Life Cycle Stage

Activity

Activity Type

Activity Code

DA

A11

DA

A12

DA

A13

DA

A14

Aluminum bar cutting

DA

B11

Aluminum extrusion bar processing

DA

B12

Aluminized sheet punching

DA

B21

Aluminized sheet bending

DA

B22

Aluminum panel painting

DA

B23

Aluminum panel insulation

IA

B24

Glass cutting

DA

B31

Glass tempering

DA

B32

Double glazing

DA

B33

Curtain-wall assembly

DA

B41

Glazing

IA

B42

Quality inspection

IA

B43

Shipment

DA

B44

Transportation

CA

C11

Carry in on-site

DA

D11

Inspection

IA

D12

Lifting

DA

D13

Installation

DA

D14

defects received

IA

E11

repair-work preparation

DA

E12

defects repair

DA

E13

Demolition

DA

F11

Delivery

CA

F12

waste treatment

DA

F13

Aluminum extrusion bar processing Raw material gathering Aluminized sheet processing & plate glass processing Manufacturing galvanized sheet iron processing

Production & assembly

Transportation

Construction

Maintaining

Dissolution

18

Table 2. The Production Amounts of Unit CW System Component Weight or Production Units

Item

Total weight of products

Main material Anchors & Bolts

Aluminum extrusion bar (Wb)

209,738 (kg)

Aluminized sheet (Wp)

37,013 (kg)

24mm tempered double-glazing (Wg)

123,350 (kg)

Galvanized sheet iron(10T) (Wz)

3,465 (kg)

The total number of production units (Eu)

2,467 (EA)

19

Table 3. Energy Consumption of Activities Activity

Equipment

Source

Consumption

unit

B11

double-bladed cutter

electricity

49,752

kwhr

B12

CNC, notching machine

electricity

54,727

kwhr

B21

Punching machine

electricity

4,045

kwhr

B22

Bending machine

electricity

4,045

kwhr

B23

Painting machine

electricity

1,618

kwhr

B31

Glass cutter

electricity

8,903

kwhr

B32

glass furnace

electricity

8,903

kwhr

B33

Double-glazing facility

electricity

8,903

kwhr

B41

Hand tool

electricity

3,317

kwhr

B44

Forklift

Fuel

600

L

C11

Delivery

5ton truck

140

EA

D11

Forklift

Fuel

600

L

D13

Tower crane (12ton)

electricity

27,450

kwhr

D14

AC arc welder

electricity

3,465

kwhr

E13

motor operated gondola

electricity

525

kwhr

F11

Backhoe, crusher, hydraulic

Fuel

5,832

L

F13

Backhoe, crusher, loader

Fuel

697

L

20

Table 4. Inventory Analysis of Each Activity (Unit: kg/unit) Life Cycle

Production & Assembly

Transport Construction Maintaining

Activi ty

CO2

CO

CH4

NOx

N2O

SO2

SOx

VOC

B11

6.24E+02

5.08E-01

1.58E+00

1.34E+00

5.92E-02

2.49E+00

3.87E-01

5.79E-02

B12

6.25E+02

5.09E-01

1.58E+00

1.34E+00

5.92E-02

2.49E+00

3.90E-01

5.79E-02

B21

1.42E+01

6.53E-02

1.55E-02

7.27E-02

1.51E-04

1.78E-02

5.23E-02

8.74E-03

B22

1.42E+01

6.53E-02

1.55E-02

7.27E-02

1.51E-04

1.78E-02

5.23E-02

8.74E-03

B23

3.20E-01

3.18E-05

2.32E-04

7.82E-04

1.00E-06

1.07E-03

B31

1.43E+01

2.99E-02

3.06E-02

4.80E-02

7.29E-05

1.58E-02

6.04E-02

1.04E-02

B32

1.43E+01

2.99E-02

3.06E-02

4.80E-02

7.29E-05

1.58E-02

6.04E-02

1.04E-02

B33

1.43E+01

2.99E-02

3.06E-02

4.80E-02

7.29E-05

1.58E-02

6.04E-02

1.04E-02

B41

6.55E-01

6.52E-05

4.75E-04

1.60E-03

2.06E-06

2.19E-03

B44

1.66E-02

3.52E-06

1.53E-06

1.47E-05

6.70E-09

2.37E-05

7.11E-06

7.26E-08

C11

1.33E-01

5.10E-05

2.58E-07

1.76E-03

4.16E-06

1.20E-06

1.22E-08

D11

1.66E-02

3.52E-06

1.53E-06

1.47E-05

6.7E-09

2.37E-05

7.11E-06

7.26E-08

D13

1.26E+01

1.26E-03

9.17E-03

3.10E-02

3.97E-05

4.23E-02

4.54E-04

D14

5.57E+00

2.71E-02

2.43E-03

3.92E-02

7.38E-05

1.02E-02

1.11E-04

5.16E-07

3.76E-06

1.27E-05

1.63E-08

1.73E-05

1.86E-07

4.14E-02

1.15E-05

2.35E-05

E11

5.18E-03

F11

1.61E-01

3.43E-05

1.49E-05

1.43E-04

6.51E-08

2.30E-04

6.91E-05

7.06E-07

F13

7.24E-04

1.54E-07

6.71E-08

6.43E-07

2.93E-10

1.04E-06

3.11E-07

3.18E-09

Dissolution

21

Table 5. Impact Assessment of ABLCA Life Cycle

Production & Assembly

Transport Construction Maintaining Dissolution

B11

Global warming 6.76E+02

B12

6.77E+02

2.00E+02

3.76E-02

5.94E-02

1.40E+03

B21

1.46E+01

6.47E+00

4.07E-04

3.22E-03

8.04E+01

B22

1.46E+01

6.47E+00

4.07E-04

3.22E-03

8.04E+01

B23

3.25E-01

8.57E-02

1.72E-06

3.46E-05

7.92E-01

B31

1.50E+01

5.79E+00

9.45E-04

2.13E-03

5.66E+01

B32

1.50E+01

5.79E+00

9.45E-04

2.13E-03

5.66E+01

B33

1.50E+01

5.79E+00

9.45E-04

2.13E-03

5.66E+01

B41

6.66E-01

1.75E-01

3.52E-06

7.09E-05

1.62E+00

B44

1.66E-02

2.15E-03

3.62E-07

C11

1.33E-01

7.07E-02

3.93E-06

7.80E-05

1.76E+00

D11

1.66E-02

2.15E-03

3.62E-07

6.51E-07

1.48E-02

D13

1.28E+01

3.39E+00

6.86E-05

1.37E-03

3.14E+01

D14

5.64E+00

4.19E+00

6.61E-04

1.73E-03

3.96E+01

E11

5.26E-03

1.39E-03

2.79E-08

5.63E-07

1.29E-02

F11

1.61E-01

2.09E-02

3.51E-06

6.33E-06

1.44E-01

F13

7.25E-04

9.44E-05

1.59E-08

2.85E-08

6.48E-04

Activity

Acidification

HH Criteria

Eutrophication

2.00E+02

3.76E-02

5.94E-02

Photochemical smog 1.40E+03

22

6.51E-07

1.48E-02

Table 6. Adjusted Environmental Impacts

B11

Global Warming Air 2.83

Acidification Air 2.30

HH Air -1.43

CriteriaEutrophication Photochemical Air Smog Air -1.23 3.15

B12

2.83

2.30

-1.43

-1.23

3.15

B21

1.16

0.81

-3.39

-2.49

1.91

B22

1.16

0.81

-3.39

-2.49

1.91

B23

-0.49

-1.07

-5.76

-4.46

-0.10

B31

1.18

0.76

-3.02

-2.67

1.75

B32

1.18

0.76

-3.02

-2.67

1.75

B33

1.18

0.76

-3.02

-2.67

1.75

B41

-0.18

-0.76

-5.45

-4.15

0.21

B44

-1.78

-2.67

-6.44

-6.19

-1.83

C11

-0.88

-1.15

-5.41

-4.11

0.25

D11

-1.78

-2.67

-6.44

-6.19

-1.83

D13

1.11

0.53

-4.16

-2.86

1.50

D14

0.75

0.62

-3.18

-2.76

1.60

E13

-2.28

-2.86

-7.55

-6.25

-1.89

F11

-0.79

-1.68

-5.45

-5.20

-0.84

F13

-3.14

-4.03

-7.80

-7.55

-3.19

23

Table 7. Classification of Environmental Impact Category Global Warming Air Impact Level

Activities

Most Sensitive

B11, B12

Sensitive

B21, B22, B31, B32, B33

Normal

B23, B41, D13, D14

Less Sensitive

C11, F11

Least Sensitive

B44, D11, E13, F13

Acidification Air Impact Level

Activities

Most Sensitive

B11, B12, B21, B22

Sensitive

B31, B32, B33

Normal

B41, D13, D14

Less Sensitive

B23, C11, F11

Least Sensitive

B44, D11, E13, F13

HH Criteria Air Impact Level

Activities

Most Sensitive

B11, B12

Sensitive

B31, B32, B33, D14

Normal

B21, B22, B41, C11, D13, F11

Less Sensitive

B23

Least Sensitive

B44, D11, E13, F13

Eutrophication Air Impact Level

Activities

Most Sensitive

B11, B12

Sensitive

B21, B22

Normal

B31, B32, B33, C11, D13, D14

Less Sensitive

B23, B41, F11

Least Sensitive

B44, D11, E13, F13

Photochemical Smog Air Impact Level

Activities

Most Sensitive

B11, B12, B21, B22

Sensitive

B31, B32, B33

Normal

C11, D13, D14

Less Sensitive

B23, B41, F11

Least Sensitive

B44, D11, E13, F13

24

Table 8. Impact Assessment of Conventional LCA Production & Assembly

Transport

Construction Maintaining Dissolution

Global Warming (kgCO2-eq/unit)

1.43E+03

1.33E-01

1.85E+01

5.26E-03

1.62E-01

Acidification (kgH+ moles-eq/unit)

4.30E+02

7.07E-02

7.58E+00

1.39E-03

2.10E-02

HH Criteria (kgmilli-DALYs-eq/unit)

7.88E-02

3.93E-06

7.30E-04

2.79E-08

3.53E-06

Eutrophication (kgN-eq/unit)

1.32E-01

3.19E-03

3.11E-03

5.63E-07

6.36E-06

Photochemical Smog (gNOx-eq/unit)

3.13E+03

1.76E+00

7.10E+01

1.29E-02

1.45E-01

25