Research Article BIM Application to Select Appropriate Design Alternative with Consideration of LCA and LCCA

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1 Mathematical Problems in Engineering Volume 205, Article ID 28640, 4 pages Research Article BIM Application to Select Appropriate Design Alternative with Consieration of LCA an LCCA Young-su Shin an Kyuman Cho Department of Architectural Engineering, Chosun University, 309 Pilmun-aero, Dong-gu, Gwangju , Republic of Korea Corresponence shoul be aresse to Kyuman Cho; cho29@chosun.ac.kr Receive 27 March 205; Accepte 0 June 205 Acaemic Eitor: Mohame Marzouk Copyright 205 Y.-s. Shin an K. Cho. This is an open access article istribute uner the Creative Commons Attribution License, which permits unrestricte use, istribution, an reprouction in any meium, provie the original work is properly cite. Avancements in builing materials an technology have le to the rapi evelopment of various esign solutions. At the same time, life cycle assessment (LCA) an life cycle cost analysis (LCCA) of such solutions have become a great buren to engineers an project managers. To help conuct LCA an LCCA conveniently, this stuy (i) analyze the information neee to conuct LCA an LCCA, (ii) evaluate a way to obtain such information in an easy an accurate manner using a builing information moeling tool, an (iii) evelope an Excel spreasheet-base framework that allowe for the simultaneous implementation of LCA an LCCA. The framework evelope for LCA an LCCA was applie to a real builing case to evaluate three possible alternatives for an external skin system. The framework coul easily an accurately etermine which skin system ha goo properties in terms of the LCA an LCCA performance. Therefore, these results are expecte to assist in ecision making base on the perspectives of economic an environmental performances in the early phases of a project, where various alternatives can be create an evaluate.. Introuction During the planning, esign, an construction of a builing, cost management has traitionally been recognize as one of the most important ecision-making factors for project participants in the construction inustry. Cost planning in the planning an esign phase of a project an monitoring an controlling in the construction phase of a project are very important management activities that can etermine the success of a construction project. Over the last 0 years, consieration of the life cycle cost (LCC) to analyze the economic feasibility has been one of the greatest changes in the fiel of project cost management []. LCC analysis (LCCA) is most effective when it is conucte in the initial phases (i.e., planning an esign phases) of a construction project. For this reason, project managers or engineers have analyze the economic feasibility of various alternatives with a focus on the iverse elements of builing, construction methos, an items [2]. In aition to consiering the LCC concept, attention has been given to greenhouse gas (GHG) emissions in all inustries aroun the globe. In particular, builings are believe to have a consierable impact on the environment because they account for more than 39% of the total primary energy consume an approximately 39% of the GHG emissions that occur in the Unite States [3]. Consequently, many stuies have been conucte to both evaluate an reuce the GHG emissions that occur in the builing prouction cycle. In particular, the methoology of life cycle assessment (LCA) is wiely use. LCA is use to evaluate the GHG emissions throughout the entire process, incluing the material prouction, transport, assembly, operation, an emolition of a builing. Just as with LCCA, LCA is effective when applie to the planning an esign phases of a construction project. LCA evaluates GHG emissions base on a comparison of various alternatives as it focuses on the construction prouction system, incluing the materials an construction methos require in the early phase to complete the construction of abuiling[4]. LCA an LCCA have three major points in common: (i) their effects can be maximize if they are conucte in the early phase of a project, (ii) they can be conucte for a prouction system that inclues all the elements of the builing an construction methos, an (iii) they provie

2 2 Mathematical Problems in Engineering an analysis process that facilitates the selection of the optimal alternative by evaluating the economic an environmental performances of the alternatives [2, 4, 5]. On the other han, it is ifficult to apply the two techniques to builings, compare to other proucts, because of the following unique characteristics of construction projects: (i) builings are large in size, with a wie variety of materials use in construction projects; (ii) there are a larger number of people involve in construction projects, an the emans of the project owner change frequently; an (iii) because each builing is unique, the prouction system is less stanarize compare to those for most other manufacture goos [6, 7]. Base on this backgroun, this stuy was conucte to evelop a metho for improving the performance of LCA an LCCA utilizing the three-imensional parametric builing information moeling (BIM) approach. This stuy was conucte using the following four steps. Instep,aliteraturereviewwasconuctetoanalyzetheLCA an LCCA process an analysis methos, while simultaneously examining their limitations an problems. In step 2, the information an ata require for LCA an the LCCA were analyze base on the results from step. The analysis leto(i)theinformationrequiretoconuctboththelca an LCCA an (ii) aitional information that was require to utilize each technique. In step 3, the BIM was aopte as an approach to provie information an ata for the LCA an LCCA implementations, which were analyze in step 2. In aition, a spreasheet-base framework, which compile the information outflow from the BIM, was evelope to conuct the LCA an LCCA simultaneously. In step 4, a case stuy, in which the evelope framework was applie to a real builing project, focuse on ientifying the applicability of the research output. The case stuy facilitate an in-epth analysis of the usefulness of the framework that was suggeste in the present stuy. 2. Step : State of the Art 2.. LCA. The LCA concept is generally accepte within the environmental research fiel. When applie to builings, LCA encompasses the analysis an assessment of the environmental effects of builing materials, components, an assemblies throughout the entire life of the builing, incluing its construction, use, an emolition [8]. Because of the increase in the number of methos for LCA an examples of its use, international organizations such as the International Stanar Organization (ISO) have worke on the stanarization of LCA, which has resulte in the ISO 4040 series. In particular, ISO 404 covers the efinition an inventory analysis of LCA an is recognize as the stanar for the LCA technique in many cases. Accoring to ISO 404, LCA coul be applie in the following four steps. (i) The LCA goal an scope are efine to secure the reliability of the analysis results by clarifying the scope of the target prouct. (ii) A life cycle input-output inventory analysis isconuctetoestablishthelifecycleinventoryatabase (LCI DB), which contains a large volume of process an prouction ata, incluing the raw material inputs, energy use, main prouct to coproucts ratio, prouction rates, an equivalent environmental releases. The unit process atasets form the basis of every LCI DB an the founation of all LCA applications. A unit process ataset is obtaine by quantifying theinputsanoutputsinrelationtoaquantitativereference flow from a specific process. These inputs an outputs are generate from mathematical relationships base on the raw ata. Consequently, a unit process is efine as the smallest element consiere in the life cycle inventory analysis in ISO (iii) An environment impact assessment is performe base on the results of the inventory analysis, an (iv) the evaluate ata is interprete. LCA can be use in a variety of ways to manage an environmental loa, compare alternatives, an establish environmental policy [9]. In the construction fiel, many stuies have been conucte to evaluate the environmental performance base on LCA analysis. Hong et al. [3] suggeste an integrate moel for assessing the cost an CO 2 emissions an calculate the CO 2 emissions base on the strength of reay-mixe concrete. In another stuy, Hong et al. [0] introuce a greenroofsystemwithenergysavingmeasuresfocusingon elementary schools in Seoul, South Korea, to analyze the cost an CO 2 emissions. Khan et al. [] evelope ecisionmaking methoology that integrate the LCA concept into risk analysis theory for ientifying optimal plant esign in theprojectearlyphase.leeetal.[2] confirmethatthe ifference in CO 2 emissions epene on the strength of the concrete accoring to the perio of use. Cole [8] confirme the ifference in CO 2 emissions using ifferent major structural systems of builings LCCA. LCCA is use to evaluate the economic feasibility base on the calculation of the equivalent values of all the important costs that occur within the life span, with particular focus on builings or the major components of builings [3]. An LCCA is conucte using the following four steps. (i) The analysis target is ientifie, which is the first step towar making a cost-effective ecision by creating an evaluating the alternatives that can meet the minimum performance stanars. (ii) The basic assumptions are establishe for the LCCA, incluing the analysis perio an iscount rate. In aition, the initial investment cost, operating cost, alteration/replacement cost, an other associate costs are confirme, an the time of the occurrence of each cost is verifie. Because these cost items occur at ifferent points in time, it is important to convert each cost to the value at a single point in time. (iii) The LCC is calculate for each alternative by aing up the costs accoring to the type for each alternative. (iv) The relate inices are calculate to evaluate the economic feasibility (the LCCA), incluing the net savings, savings-to-investment ratio, an payback perio. In aition, a sensitivity analysis can be implemente to complement the LCCA methoology, which will provie reliability to the LCCA results. Many previous stuies have examine LCCA. Early stuies on the LCC focuse on minimizing the installation cost in the initial phases of builing construction an maintenance, along with the replacement cost in the operation phase. Recently, attention has been given to stuies on the energy cost in the operation phase, with the goal of evaluating

3 Mathematical Problems in Engineering 3 the environmental performance of various materials an construction methos. For example, Uygunoğlu an Keçebaş [4] analyzetheenergysavingperformanceinrelationtothe formanthicknessofaconcreteblockanexaminethe payback perio accoringly. Wong et al. [5] conucte an LCCA when green roof systems were use, which aime at proving economic effects. Zhang an Wang [6] examine the economic performance of thermal power plants using LCCA. Chang et al. [7] uselccatoanalyzethewaterconservation an energy saving effects of green roof systems an examine the cost-reuction effects of those systems. Akairi et al.[8] evelope an assessment moel base on the use of iverse sustainable materials an suggeste costreuction effects that coul be attribute to the use of sustainable materials.fu et al. [9] suggeste a new algorithm for calculating the carbon emission in orer to optimize builing plans in terms of sustainability through comparing the five LCA tools Integration of BIM into LCA an LCCA. While BIM efinitions vary significantly accoring to the organization an researcher, the common concept is that the BIM is a program or process for extracting an reusing ata by eveloping a moel, which is presente in a multiimensional virtual space, using the ata on the life cycle of a construction project [20, 2].Currently,BIMisusewielyintheconstruction inustry because of the following avantages: (i) a graphic user interface, which provies a work environment where the operator can observe the work visually, (ii) convenient moification an aition because object-base moeling can be performe, which leas to excellent esign changes an alternative comparisons, an (iii) the prouction of iverse information with high usability. In other wors, onetime moeling allows for the prouction of various esign ocuments an quick an accurate quantity estimation for variousalternatives[22]. Several previous stuies on BIM have been conucte, but very few stuies have been conucte that escribe the integration of BIM into LCA an LCCA. Basbagill et al. [23] evelope a combine BIM-LCA metho to figure out which materials an superstructure esigns coul be effective in terms of CO 2 emissions reuction accoring to BIM prescriptions for replacing materials in ifferent types of structures. Consequently, it is possible to provie a metho to help engineers select materials an superstructures appropriately uring the early phases of a project. Han et al. [24] suggeste an optimization metho for builing components that integrates genetic algorithms into the BIM approach, along with the LCCA result for each component. In this research, the BIM approach was utilize to calculate the energy consumption as a function of the installation of each component. Ristimäki et al. [25] evelope a moel for combining LCA an LCCA, in which a single energy system was aopte. This research emonstrate that the evelope moelwaslimitetoasmallpartofabuiling,becauseof the ifficulty in acquiring the ata necessary to conuct the two analysis methos simultaneously. Ion an Firth [26] analyze CO 2 emissions of a small welling house uring theplanningphase,wheretheyutilizethebimapproachto consier various alternatives to builing components, incluing structure an envelope systems. In the previous research reference above, BIM has been use mostly to conveniently generate various esign alternatives for conucting LCA or LCCA analysis, but there have been few ieas or theories on how BIM coul not only be integrate to conuct LCA an LCCA, but also how to conuct them simultaneously Problem Statements. Given the increase focus on the economic an environmental performances of construction projects, most of the elements comprising projects have been consiere in evaluations of their performances using LCA an LCCA. Despite this, the previous stuies that were conucte ha the following limitations. (i) The analyses were limite to a small number of esign alternatives, because a large volume of ata was neee to implement the LCA an LCCA. (ii) Some recycling of previous ata was neee for each implementation of the LCA an LCCA because of the unique characteristics of construction projects. (iii) There has been little research focuse on the application of the BIM approach for conucting LCA an LCCA simultaneously, for the purposes of reucing an recycling the information require for the two methos. Base on this backgroun an the ientifie problems, this paper proposes a metho for efficiently performing LCA an LCCA, while reucing an recycling the information require for the two methos. This paper (i) ientifies the information neee to conuct the LCA an LCCA (in step 2), (ii) shows how the information require for the two methos can be obtaine conveniently using a BIM approach (in step 3), an (iii) emonstrates how the LCA an LCCA canbecomputesimultaneously,baseontheevelope framework, which incorporates the information obtaine using the BIM approach (in step 3). 3. Step 2: Ientifying Data Require for Conucting LCA an LCCA As the first stage for eveloping a metho that facilitates the LCA an LCCA implementation, in step 2, the information require for conucting the two methos was ientifie, along with each phase of the LCA an LCCA (i.e., construction, operation, an isposal) an the target activities of that phase, as liste in Table. 3.. Require Data for LCA an LCCA in Construction Phase. Accoring to the LCA methoology by the ISO, the target activities of the LCA in the construction phase of a builing consist of the prouction, transport, an assembly of materials. Accoring to Hong et al. [3], an examination of previous stuies relate to LCA showe that the environmental impact factors generate in the construction phase can generally be calculate using (). As shown in this equation, the quantity of environmental emissions in the construction phase for system A (EQ Con A ) is the sum of the environmental impacts from the releases uring prouction, transport, an assembly: () Environmental emissions in the prouction process: if system A consists of i materials, the environmental

4 4 Mathematical Problems in Engineering Life cycle phase Construction Target activities for conucting LCA an LCCA Table : Data require for conucting LCA an LCCA. Manufacturing factory e e Transporting e e (i) Fuel type Assembling site e e (ii) Fuel consumptions Require information for LCA Require information for LCC Q EF Aitions Q UC Aitions (i) Operation perio (ii) Repair cycle (iii) Repair rate e e (i) Unit cost, incluing labor an equipment costs. It can be foun usingrsmeansata (i) Operation perio (ii) Repair cycle (iii) Repair rate Maintenance an repair e e e e Operation Replacement e e (i) Replacement cycle e e (i) Replacement cycle Operating e (i) Energy consumption e (i) Energy consumption Disposal Disposal e e (i) Fuel type (ii) Fuel consumptions e e (i)unitcostforisposal n Q =quantityofmaterials,ef=emissionfactor,anuc=unitcost. impacts generate in the prouction process can be calculate by multiplying the quantity of each material (Q M a ) an the emission factor of the environmental release when manufacturing that material (EF M a ). In general, the emission factor of each material canbereferrefromthelcidbofthecountries. (2) Environmental emissions in the transport process: if manufacture materials are transporte to the construction site by j number of vehicles, the environmental impacts can be calculate by multiplying the quantity of each vehicle (Q V b ) by the emission factor of the environmental release of that vehicle (EF V b ). (3) Environmental emissions in the assembly process on site: if k number of the equipment is use to assemble the materials at the construction site, the environmental impacts can be calculate by multiplying the quantity of equipment (Q E c ) by the emission factor of the environmental release of the iniviual pieces of equipment (EF E b ). (4) To etermine the emission factors of the transport vehicles an installation equipment, (i) the fuel type (i.e., gasoline, iesel, etc.) for each vehicle an piece of equipment for conucting the work shoul first be ientifie, an then (ii) the emission factors, along with the fuel type, can be foun by referring to the LCI DB [27]. (5) With consieration of the above environmental impacts in each element, the amount of environmental emissions in the construction phase can be calculate using EQ Con A = i a= (Q M a EFM a )+ j b= (Q V b EFV b ) () k + (Q E c EFE c ), c= where EQ Con A = the quantity of environmental emissions in the construction phase for system A, Q M a =thequantityofmateriala comprising system A, EF M a = the emission factor of the environmental release while manufacturing material a, Q V b =the number of vehicles use to transport material b, EF V b = the emission factor of the vehicle use for material b, Q E c = the pieces of installation equipment, an EF E c = the emission factor of the equipment. Generally, accoring to Dell Isola an Kirk [3], the costs of items in the construction phase to conuct the LCCA can be calculate using (2). IfsystemA woul consist i of materials, the installation costs of system A (C Ins A )canbe etermine by multiplying the quantity of each material in the system by the installation cost of a unit area (i.e., unit cost). The unit cost generally refers to reporte ata such as from RS Means. Thus, such ata inclues the labor cost an equipment cost per unit area: C Ins A = i (Q M a UC a), (2) a= where C Ins A = the installation cost of system A, QM a =the quantity of material a comprising system A, anuc a =the unit cost for installing material a (i.e., $/m 2 ). As escribe above an liste in Table,to conuct the LCA an LCCA in the construction phase, it is necessary to obtain the following information: (i) the quantity of each material in the targete system an the quantity of each set of equipment for transportation an installation, (ii) the emission factor of each material an piece of equipment, an (iii) aitional information such as the fuel type an fuel consumption of equipment, as well as the unit installation cost Require Data for LCA an LCCA in Operation Phase. The target activities of the LCA in the builing operation phase consist of maintenance an repair (M&R), replacement, an operation. Accoring to previous stuies, the quantity of environmental emissions generate uring the operation phase can be calculate as follows [28]: () Environmental impacts for M&R an replacement: these can be calculate in the same manner as

5 Mathematical Problems in Engineering 5 the environmental impacts uring the construction phase. Along with the expecte occurrence times for the replacement an M&R of the system, environmental impacts can be calculate consiering the quantity an emission factors of the material, transport vehicle, an installation equipment. (2) Environmental impacts uring operation: these are calculate by multiplying (i) the annual quantity of energy consumption (Q E a ) for each type (i.e., heating, air-conitioning, appliance, etc.) neee for the operation of builings, (ii) the emission factors of environmental release epening on the energy type (EF E a ), an (iii) the perio in operation (n) (referto (3)): EQ O A =(QE a EFE a ) n, (3) where EQ O A = the quantity of environmental emissions uring the operation phase for system A, Q E a =the annual energy consumption of the system, EF E a =the emission factor of environmental release epening on the energy type, an n = the perio in operation. The LCCA uring the operation phase inclues the M&R anenergycosts,whichcanbecalculateusing(4) an (5), respectively: () Maintenance, repair an replacement costs (C MR A ): along with the expecte occurrence times of the M&R an the replacement of the system, the costs are calculate by multiplying (i) the quantity of each item )insystema that requires maintenance, repair, an replacement by (ii) the unit cost (UC MR )for such target activities. Moreover, because M&R an replacement costs will be incurre in the future, the equivalent present worth of the costs iscounte at theinterestrate(dr)forthem&ranreplacement time (T ) shoul be consiere (please refer to [3]for the etails): (Q MR C MR A = l = (Q MR UC MR ( + DR) T ), (4) where C MR A = the present worth of total M&R an replacement costs of system A, Q MR =thequantityof each item comprising the system that requires M&R an replacement, UC MR =theunitcostform&ran replacement, DR = the iscount rate, an T =the M&R an replacement time of each item. (2) The operation energy cost (C E A ) is the prouct of the quantity of annual energy consumption (Q E a )anthe unit cost of the energy source (UC E ). Moreover, because the cost is a future cost that occurs annually, the iscount rate (DR) for the operation perio (n) is consiere to convert the cost to an equivalent present value in total (please refer to [3] for the etails): C E A = (QE a UCE ) ( + DR)n n, (5) DR ( + DR) where C E A = the present worth of total energy cost of system A uring n years, Q E a = the annual energy consumption of the system, UC E =theunitcostof the energy source, an n = the perio in operation. As escribe above an liste in Table,to conuct the LCA an LCCA uring the operation phase, it is essential to obtain (i) the quantity information, (ii) information on the emission factor, an (iii) aitional information such as information on the M&R an replacement (i.e., operation perio, repair cycle, repair rate, replacement rate, etc.) an information on the energy (i.e., energy consumption an energy cost) Require Data for LCA an LCCA in Disposal Phase. During the isposal phase of the builing, the LCA an LCCAcanbeconuctebaseon(6) an (7), respectively [28]. The quantity of environmental emissions uring the isposal (EQ D A ) can be calculate consiering the quantity of the isposal equipment (Q ED )antheemissionfactoraccoring e to the energy type of the iniviual pieces of equipment )(referto(6)). Therefore, (EF ED e EQ D m A = e= (Q ED e EF ED e ). (6) The isposal cost (C D A ) can be calculate by multiplying the isposal quantity (Q D A ) by the unit cost (UCD A )forthe isposal work. Similar to the M&R cost, the isposal cost nees to be converte to an equivalent present cost iscounteatacertaininterestrate(dr)forthetimeofthe isposal (T ), because the cost will be incurre in the future (refer to (7)). Therefore, C D A =QD A UCD A ( + DR) T. (7) AsescribeaboveanlisteinTable,thefollowingare neee to conuct the LCA an LCCA uring the isposal phase: (i) the quantity information, (ii) information on the emission factor, an (iii) aitional information such as the fuel type an consumption of the equipment an unit cost for isposal Require Data for LCA an LCCA. As analyze in this step, a large amount of information is neee to conuct the LCA an LCCA, which makes project managers hesitant to apply these techniques. In aition, even if they are use, it is ifficult to apply them to a range of alternatives. Therefore, this stuy evelope a metho to overcome the problems associate with conucting LCA an LCCA base on easiness of ata acquisition an ata recycling. This

6 6 Mathematical Problems in Engineering section ientifies the ata require for LCA an LCCA, along with the project phase, an then classifies the ata into two categories: (i) the ata commonly require an (ii) aitional ata, aslistein Table. 4. Step 3: Framework for Conucting LCA an LCCA Instep3,aframeworkfortheLCAanLCCAwasevelope using the following process: (i) mapping between the require LCA an LCCA ata analyze in step 2 an the acquirable ata from BIM an (ii) emboying the calculation methos (Equations () to (7)) an all the ata neee for LCA an LCCA into an Excel spreasheet-base framework. 4.. Mapping Require Data for LCA an LCCA with BIM Data. Despite some ifferences between the ifferent types of BIM software, the application of BIM generally facilitates the acquisition of the following ata: (i) visual moel ata expresse in a three-imensional space, (ii) information on a quantity estimation, (iii) information on the necessary energy consumption to operate a builing through an energy simulation, an (iv) information on construction interference among work activities [29]. As liste in Table, it is important to obtain iverse information to conuct the LCA an LCCA. Therefore, mapping can be performe as follows between the ata that can be obtaine from the BIM an the information that is require to conuct the LCA an LCCA: (i) Quantity information about the material resources for each alternative: as liste in Table,the basic ata to conuct the LCA an LCCA are information on the quantity of the input resource for each life cycle of the builing. Among such iverse quantity information, information about the quantity of materials use to form the relevant builing is funamental to conucting the LCA an LCCA. This is because information about the quantity of materials has the greatest influence on making a ecision base on the results of the LCA an LCCA in the construction an operation phases. Such information about the quantity of materials can be reaily obtaine from BIM. Furthermore, information about the quantities ofmaterialsforvariousalternativescanbeobtainein aconvenientanaccuratewayinthefeasibilityphase of a project, in which the level of change in the esign plan can be significant. (ii) Energy consumption: consiering the recent tren of usingmanyenergysavingtechniques,energyconsumption is the most important factor among the factors that affect the results of the LCA an LCCA in the operation phase of a builing. If the BIM is use in the operation phase, it is possible to obtain information on the energy consumption in a case where various energy saving techniques are applie. In aition to a builing information moel of a particular builing, information on the following builing conitions is require for analyzing the builing s energy consumption: its location, azimuthal angle, climate conition, mechanical systems, an thermal conuctivity performance. Once these conitions have been establishe, the BIM software can calculate the energy consumption of the builing, expresse by parameters such as the monthly energy balance. In the elivery process for an environmentally frienly builing, the following aspects have recently become important great issues: (i) information about the quantity of materials an ata on the energy consumption are the most funamental for conucting the LCA an LCCA for various esign alternatives, epening on the application of energy saving techniques; an (ii) the convenient acquisition of such core ata from the BIM can be a great benefit when the LCA an LCCA are implemente in the elivery process for an environmentally frienly builing. In the meantime, the remaining ata liste in Table (i.e., the LCI DB, machinery ata, operation perio, etc.) can be obtaine base on the existing methoologies for the LCA an LCCA Framework for Conucting LCA an LCCA Using BIM. Because the ata obtaine from BIM are reaily compatible with an Excel spreasheet, the framework was establishe using the spreasheet program, in which the LCA an LCCA implementation methos are automatically connecte to each other. As shown in Figures through 4, theframework consists of four sheets in total, incluing three sheets for conucting the LCA an LCCA in the construction phase, operation phase, an isposal phase an one sheet for summarizing the results from these three sheets. Meanwhile, the ata on each sheet can be entere manually after it has been extracte automatically using BIM Worksheet for Construction Phase. As shown in Figure, cell lines to 6 on the sheet represent the quantity information that is commonly require to conuct the LCA an LCCA for the system, which was extracte automatically using the BIM. In other wors, cell lines an 2 show the material information for each system, whereas cell lines 3 to 6 present the quantity information for each material, incluing theweight(i.e.,cellline3)antheequivalentvolume(i.e., cell line 4), area (i.e., cell line 5), an length values (i.e., cell line 6) corresponing to this weight. Cell lines 7 to 25 are use for inputting the information that is neee to conuct the LCA for the equipment that is use in manufacturing (cell lines 0 to 7), transport, an construction (cell lines 22 to 25). In aition, (i) the fuel type of the input equipment an vehicles for material manufacture, transport, an construction (i.e., electricity, iesel, an gasoline) an (ii) the capacity of the equipment an vehicles (i.e., kg/ea, m 3 /EA, m 2 /EA, an m/ea) make it possible to calculate the require amount of fuel for the equipment an vehicles for the manufacture, transport, an construction (i.e., cell lines 8 an 26). Subsequently, the emission factors

7 Mathematical Problems in Engineering 7 A B C D E F G H I J K L M N O P Q R S T U V W X Y System A System N Quantities 2 Material Material 2 Material i 3 BIM Weight (kg) Q 4 ata Equivalent volume (m 3 M Q ) EV Q M i M 5 Equivalent area (m 2 EV Q ) EA Q M i M EA Q 6 Equivalent length (m) EL Q M i M EL Qi M 7 Fuel types of equipment Fuel types of equipment 8 Manufacturing equipment Electricity Gasoline Diesel Electricity Gasoline Diesel Electricity Gasoline Diesel 9 C F 2 F/C 3 C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C 0 (kg) E G0 = F0/E0 E. 2 Equipment (m 3 ). 3 capacity. 4 per hour 5 (m 2 ).. 6 (m). 7 E E8 = E3 SUM(G0:G) + E4 SUM(G2:G3) + E5 SUM(G4:G5) + E6 SUM(G6:G7) k E 8 User Fuel s sum for equipment Q E Q _e _g E Q_ E Q2_e E Q E Q 2_g 2_ E Qi_e E Qi_g E Qi_ E 9 input Transportation Fuel types of vehicles Fuel types of vehicles 20 ata an Electricity Gasoline Diesel Electricity Gasoline Diesel Electricity Gasoline Diesel 2 construction vehicles C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C FF/C C F F/C 22 E G22 = F22/E22 Vehicle (kg) V 23 capacity. 24 (m 3 per hour ). 25 E E26 = E3 SUM(G22:G23) + E4 SUM(G24:G25) j V 26 Fuel s sum for vehicles Q_e V Q_g V Q_ V Q V Q 2_e 2_g V Q2_ V Qi_e V Qi_g V Qi_ V 27 Emission factors For material Material Material 2 Material i 28 EF M EF M 2 EF M i 29 (LCI DB) Electricity Gasoline Diesel Electricity Gasoline Diesel Electricity Gasoline Diesel For equipment 30 EF e EF g EF EF e EF g EF EF e EF g EF 3 Unit cost ($/m 2 ) UC A UC N 33 LCA CO EQ con 2 emission quantity for materials (kg) E33 = E3 E result CO 2 emission quantity for machinery (kg) EQ con2 _e EQ con2 _g EQ con2 _ EQ con2 2_e EQ con2 EQ con2 2_g 2_ 35 LCC result Initial costs ($) CA Ins C = capacity per one cycle F 2 = fuel value for the capacity F/C 3 = resource per unit capacity EQ con E34 = (E8 + E26) E30 E35 = E5 E3 EQ con EQ con2 N 2_x C Ins N Y33 = SUM(E33:X33) Y34 = SUM(E34:X34) Y35 = SUM(E35:X35) Total EQ con Total EQ con2 Total C Ins Figure : Worksheet for LCA an LCC analysis in construction phase. accoring to the type of material an equipment from the LCI DB (cell lines 27 to 30) are use to calculate the CO 2 emission quantity for materials an machinery (cell lines 33 an 34). To calculate the construction costs comprising the LCC, it is necessary to input the unit cost (cell line 3) of each system, which can be provie by RS Means, an so forth Worksheets for Operation an Disposal Phases. As shown in Figure 2 an (3) to (5), the material quantities an energy requirements per year, which can be extracte by the BIM program, are use to conuct the LCA an LCCA in the operation phase. Base on this information an program, if a user enters (i) the electricity price (i.e., cell (D7) in Figure 2), (ii) unit cost (i.e., aopte from the sheet construction phases, cell (E3) in Figure ), an (iii) operation information per system (i.e., cells (D9) to (D5) in Figure 2), they can automatically obtain the LCA an LCCA results in the operation phase. The LCA an LCCA in the isposal phase are performe in a manner similar to that in the construction phase. They are also conucte base on the input values for the equipment use to emolish builings (refer to Figure 3) Worksheet for Summary. This sheet inclues the results corresponing to Total on sheets to 3 above (i.e., line 33, line 34, an line 35 of column Y on sheet ; line 9, line 20, anline2ofcolumnlonsheet2;anline6anline7of column Y on sheet 3) (refer to Figure 4). 5. Step 4: Case Application A case application was conucte to verify the usability of the evelope framework an the methoologies for conucting thelcaanlcca.thefollowingpresentsanoverviewof the builing project selecte for the application: (i) Location: Hak-ong, Dong-gu, Gwangju, Republic of Korea. (ii) Structural system: steel-reinforce concrete structure.

8 8 Mathematical Problems in Engineering A B C D E F G H I J K L System A System N Quantities 2 Material Material 2 Material i 3 Equivalent area (m 2 ) EA Q M EA Qi M BIM 4 ata Source Electricity 5 Energy Energy type simulation Heating Hot-water Air-conitioning Ventilation supply fan Appliance 6 Energy requirement (MWh/yr) ER H ER HW ER AC ER V ER A 7 Electricity price ($/MWh) UC E 8 Unit cost ($/m 3 ) UC A UC N 9 Replacement term (yr) 0 Maintenance term (yr) User Maintenance rate (%) input Operate 2 Stuy perio (yr) 3 ata information Number of replacement times D6 = D3 D8 4 Number of maintenance times 5 Discount rate (%) D7 = (D3 D8) D 6 Replacement cost ($) UC MR A UC MR N 7 Maintenance cost ($) UC MR2 A UC MR2 N 9 LCA CO 2 emission quantity result uring operation phase (kg/yr) EQ E EQ E H HW EQ E AC EQ E V EQ E A 20 LCC Energy costs ($) C E 2 result R&M costs ($) Unit cost = aopter from the sheet for construction phase D2 = D6/( + D5)^(D9 D3) + D7/( + D5)^(D0 D4) + CA MR D20 = (SUM(D6:H6) D7) (( + D5)^D2 )/(D5 ( + D5)^D2) L9 = SUM(D9:H9) L20 = D20 MR L2 = SUM(D2:K2) C N Total EQ E Total C E Total C MR Figure 2: Worksheet for LCA an LCC analysis uring operation phase. A B C D E F G H I J K L M N O P Q R S T U V W X Y System A System N Quantities 2 BIM Material Material 2 Material i 3 ata Weight (kg) Q 4 Equivalent volume (m 3 M Q ) EV Q M i M EV Qi M 5 Disposal cost ($/kg) UC D A UC D N 6 Stuy perio (yr) Operate 7 information Discount rate (%) 8 Fuel types of equipment Fuel types of equipment 9 User Disposal equipment Electricity Gasoline Diesel Electricity Gasoline Diesel Electricity Gasoline Diesel 0 input C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C ata F 2 F/C 3 Equipment G = F/E capacity (m 3 ) E per hour m ED E2 = E4 G 2 Fuel s sum for equipment Q_e ED Q_g ED Q_ ED Q2_e ED Q2_g ED Q2_ ED Qi_e ED Qi_g ED Qi_ ED 3 Emission For Electricity Gasoline Diesel Electricity Gasoline Diesel Electricity Gasoline Diesel 4 factors (LCI DB) equipment EF e EF g EF EF e EF g EF EF e EF g EF 6 LCA CO 2 emission quantity EQ ED _e EQ ED _g EQ ED _ EQ ED 2_e EQ ED 2_g EQ ED 2_ result for machinery (kg) 7 LCC Disposal costs ($) C result A D E6 = E2 E4 E7 = (E3 E5)/( + E7)^E6 EQ ED i_x C D N Y6 = SUM(E6:X6) Y7 = SUM(E7:X7) Total EQ ED Total C D C = capacity per one cycle F 2 = fuel value for the capacity F/C 3 = resource per unit capacity Figure 3: Worksheet for LCA an LCC analysis in isposal phase.

9 2 2 Mathematical Problems in Engineering 9 A B C Phase Assessment LCCO 2 LCC 2 Total EQ con B2 = construction phase!y33 Construction 3 Total EQ con2 Total C Ins B3 = construction phase!y34 4 Operation Total EQ E Total C MR B4 = operation phase!l9 5 Total C E 6 Disposal Total EQ ED B6 = isposal phase!y6 Total C D 7 SUM Total emission quantity B7 = SUM(B2:B6) Total costs C2 = construction phase!y35 C4 = operation phase!l20 C5 = operation phase!l2 C6 = isposal phase!y7 C7 = SUM(C2:C6) Figure 4: Summary worksheet for LCA an LCC analysis. 3 3 z y x z y x Original moel an alternative moel 2 (a) Alternative moel (b) Figure 5: Results of BIM for each alternative. (iii) Type: office builing. (iv) Stories an floor area: stories (one story below groun an 0 stories above groun), a builing area of m 2, an a gross floor area of 7,05.94 m 2. Because it is important to obtain a large volume of ata to conuct the LCA an LCCA for the entire builing, the application of the evelope framework was esigne to focus only on the external skin of a builing. In aition, thelcaanlccawereconuctewithparticularfocuson the construction an operation phases. Because the external skin of a builing plays an important role in achieving energy efficiency, it has a remarkable effect on the results of the LCA an LCCA. Consequently, among the various alternatives for the skin of a builing, it is possible to select the most valuable skin system base on the LCA an LCCA results, if the evelope framework is use. In this stuy, the authors consiere three alternatives for the external skin system, incluing the original external skin system. The following escriptions give an overview of each alternative: (i) Original skin system: 22 mm ouble-glaze curtain wall (5 mm glass + 2 mm air layer + 5 mm glass) with athermaltransmittanceof2.79w/m 3 K. (ii) Alternative : cement brick wall with ouble-glaze winows (5 mm glass + 6-mm air layer + 5 mm glass) with a thermal transmittance of 3.25 W/m 3 K. (iii) Alternative 2: 24 mm low-e glass curtain wall (6 mm glass + 2 mm argon layer + 6 mm low-e glass) with a thermal transmittance of.80 W/m 3 K. 5.. Moeling an Data Acquisition. The moeling of the builing was performe using the ArchiCAD version 5 software in the following orer: (i) creation of site, (ii) creation of structural columns, (iii) creation of bearing wall, an (iv) creation of the slab. After one story was complete, copy an paste commans, along with the gri system function, were use to complete the moeling of the floors (up to the 0th floor). Next, the moeling of the external skin system for each alternative was performe before entering the attribute information. The time require was approximately 2 h. Figure 5 presents the complete 3D builing information moel. As mentione, the moeling of the internal space wasexcluefromthiscasestuybecausethepurposeof the case application was to conuct the LCA an LCCA for each alternative external skin system. Accoring to several previous stuies, the skin system of a builing critically affects its thermal conuctivity performance. Consequently, the skin system coul be regare as one of the most important

10 0 Mathematical Problems in Engineering Table2:QuantityanenergyataobtainebyBIM. Type of ata from BIM Properties of each alternative Original skin Alt. Alt. 2 Aluminum frame Volume (m 3 ) Weight (kg) 56,85 50,23 56,85 Glass Volume (m 3 ) Weight (kg) 25,32 46,23 30,385 Cement brick Volume (m 3 ) 68.6 Weight (kg) 20,264 Quantity ata Mortar Volume (m 3 ) 6.4 Weight (kg) 6,020 Polystyrene Volume (m 3 ) 4.2 Weight (kg) 426 Concrete Volume (m 3 ) 3.24 Weight (kg) 74,976 Argon Volume (m 3 ) 2.77 Weight (kg) 7.62 Heating Hot-water supply Energy amount (MWh/yr) Air-conitioning 2,653 2,737 2,487 Ventilation fan Appliance,770,770,770 Total consumption 5,55 5,25 4,986 factors affecting the energy consumption of a builing. Therefore, this research was structure to conuct energy simulations base on numerous alternatives for builing skin systems, while the other simulation conitions were fixe. As escribe in step 3, the aitional information necessary for calculating the energy consumption uring the operation phase was set as follows: (i) location (35 9 in latitue an in longitue), (ii) bearing angle (340 ), (iii) type of use (office builing), (iv) climate ata: KOR Kwangju IWEC [30], an (v) type of air-conitioning an heating system (central system). Once the moeling was complete, (i) the element function of ArchiCAD was use to retrieve the quantity information for each alternative external skin, an (ii) EcoDesigner, which is an a-on function of ArchiCAD, was use to calculate the energy consumption for each alternative, all of which are liste in Table 2. Accoring to the calculations, alternative 2, in which low-e glass was use, showe the lowest total energy consumption (4,986 MWh/yr) Input Data for LCA an LCCA. To conuct the LCA an the LCCA for the three target alternatives, it was important to provie the information neee by the three worksheets (i.e., Figures, 2, an3). For example, Figure 6 shows the input ataanresultsfortheworksheetintheconstructionphase when the original skin system (i.e., normal curtain wall) was use. As shown in the figure, the information obtaine from the BIM provie quantity information on aluminum an glass(i.e.,cell(e3)tocell(e6)ancell(n3)tocell(n6)in Figure 6),whicharethemainmaterialscomprisingtheoriginal skin system. Secon, because (i) three sets of equipment (i.e., aluminum cutter, notching clipper, an painter) were use for manufacturing the aluminum, (ii) they were operate by electricity, an (iii) they manufacture raw aluminum in length units; the equipment capacity an fuel requirement were entere into cells (E4) to (E6) an cells (F4) to (F6), respectively. Similarly, the capacity an fuel requirement of the equipment for glass manufacturing were entere, as shown in Figure 6 (i.e., cells (N0) to (N3) an cells (O0) to (O3)). In aition, the capacity an fuel requirement of the vehicles use for construction (i.e., a forklift, tower crane, an loaer) were entere into lines 2 to 23, accoring to their fuel types. Finally, the unit cost of $79.737/m 2 for the curtain wall installation work was entere base on the Korean Price Information for Construction Work, which is similar to the cost ata provie by RS Means in the USA [3]. To calculate the LCA an LCCA uring the operation phase, (i) the analysis perio use when simultaneously conucting the LCA an LCCA was etermine to be 40 years, which was the life span of the reinforce concrete builing as stipulate by legislation, an (ii) the iscount rate for the LCCA was calculate base on the inflation rate an eposit interest rates over the past 0 years, which were provie by the Bank of Korea. 6. Results an Discussion 6.. LCA an LCCA Results. Table 3 lists an Figure 7 shows the LCA results. As liste in Table 3,whenabuilingis operate for 40 years, among the three alternatives, alternative 2 has the lowest CO 2 emission (low-e curtain wall system: 26,389,800 kg). The CO 2 emission of alternative 2 (i.e., 944,786 kg) is the highest among the three alternatives in

11 Mathematical Problems in Engineering Table 3: LCA an LCCA results for each alternative. LCA results (kg) LCCA results (US $) CO 2 emission in construction phase CO 2 emission in operation phase CO 2 emission in isposal phase Builing skin system Original skin Alt. Alt. 2 Aluminum frame 839, ,0 839,987 Glass 00,432 39,2 04,346 Manufacturing Cement brick 2,39 Mortar 6,873 Polystyrene 826 Concrete 3,23 Argon 453 Construction 940,49 84, ,786 Energy consumption One year (kg/yr) 668,30 675, , years (kg) 26,732,400 27,022,880 26,389,800 Disposal (kg) Total amount of CO 2 emission 27,672,400 (kg) 27,864,438 (kg) 26,389,800 (kg) Construction phase Initial investment costs 9,220 96, ,988 Operation phase Replacement an maintenance costs 36,765 32,938 60,20 Energy costs 8,204,352 8,359,094 7,935,464 Disposal phase Disposal costs 9,565 4,507 0,54 Total amount costs $8,54,902 $8,703,462 $8,329,808 A B C D E F G H I J K L M N O P Q R S T U V W Quantities Normal curtail wall installation 2 Aluminum Glass 3 Weight (kg) 56, , BIM ata Equivalent volume (m 3 ) Equivalent area (m 2 ) (N/A) Equivalent length (m) (N/A) 7 Fuel types of equipment 8 Manufacturing equipment Electricity Gasoline Diesel Electricity Gasoline Diesel 9 C F 2 F/C 3 C F F/C C F F/C C F F/C C F F/C C F F/C 0 Glass reinforcer (kg) Glass multilayer Glass cutter Equipment (m 2 ) Spattering equipment capacity Aluminum cutter per hour (m) Nothing clipper Painter User Fuel s sum for equipment 38, , input ata Transportation an construction Fuel types of vehicles 9 Electricity Gasoline Diesel Electricity Gasoline Diesel 20 vehicles C F F/C C F F/C C F F/C C F F/C C F F/C C F F/C 2 Vehicle (kg) Fork-lift capacity Tower crane per hour (m 3 ) Loaer Fuel s sum for vehicles For material Aluminum Glass 26 Emission factors For equipment Electricity Gasoline Diesel Electricity Gasoline Diesel 28 (LCI DB) Unit cost ($/m 2 ) LCA CO 2 emission quantity for materials (kg) 82, , ,04 32 result CO 2 emission quantity for machinery (kg) 8, , , LCC result Initial costs ($) 9, ,220 C = capacity per one cycle F 2 = fuel value for the capacity F/C 3 = resource per unit capacity Figure 6: Example of application of worksheet for construction phase.

12 2 Mathematical Problems in Engineering Break-even point (6.6 years) 40 (kg) 30 Break-even point (6.6 years) 20 (6 yrs.) (7 yrs.) 0 <Cumulative emissions> Low-E curtain wall> Normal curtain wall> Masonry wall <Cumulative emissions> Normal curtain wall> Masonry wall> Low-E curtain wall Normal curtain wall Masonry wall Low-E curtain wall (years) Figure 7: Results for accumulating LCA amount over years. the construction phase but the lowest (659,745 kg/yr) in the operation phase. Therefore, alternative 2 was foun to have the lowest total amount of CO 2 emissions. Figure 7 shows the cumulative CO 2 emissions over the operation time. This alternative (low-e curtain wall system) can be consiere to be the most environmentally frienly alternative after 8 years. In aition, Table 3 lists an Figure 8 shows the LCCA results. As liste in Table 3, when the builing is operate for 40 years, among the three alternatives, alternative 2 is the most economical (low-e curtain wall system: $8,329,808). The initial investment cost of alternative 2 is the highest ($223,988) among the three alternatives, whereas the energy cost of alternative 2 is the lowest ($7,935,464). Therefore, alternative 2 was foun to be the most economical in terms of the total amount cost. As shown in Figure 8, which epicts the cumulative LCC over the operation time, alternative 2 can be consiere to be the most avantageous alternative in terms of the cost at the time point of 3.4 years because the energy cost is the lowest Avantages an Disavantages of Applying BIM Technique to Conuct LCA an LCCA. Given the recent trens in the construction inustry, which place emphasis on the economic an environmental performance, LCCA an LCA have been wiely use. However, their implementation has been a great buren to engineers an project managers. The application of the results of this stuy will be useful in resolving such problems. In the case application results, it took approximately 2 hours to perform the BIM for the three alternatives for the external skin system, an the moel provie information on the material quantities require an energy consume, which are key items of information for conucting LCA an LCCA. The methoology suggeste in this paper can be use to obtain LCA an LCCA results in an efficient manner. TheBIMmaeitpossibletoobtaintheresultsofthe quantity calculation immeiately, an it is compatible with other software because commercial BIM programs can provie their results as Excel spreasheet. Because various esign ocuments are use to conuct the existing twoimension-base quantity calculations, a large amount of time is require, an errors occasionally result. On the other han, because the BIM can provie relevant information immeiately, it is possible to save time in the early phase of theconstructionprojectanobtainmoreaccuratequantity information. In aition, it is important to analyze the energy consumption that is require in the operation phase, wherein thelcaanthelccaareconucte,whichrequiresconsierable time an effort. The energy evaluation function of

13 Mathematical Problems in Engineering ($) 5 0 Break-even point (3.4 years) Break-even point (3.2 years) Break-even point (3.4 years) Break-even point (3.2 years) 5 <Cumulative costs> Normal curtain wall> Low-E curtain wall> Masonry wall <Cumulative costs> Low-E curtain wall> Normal curtain wall> Masonry wall (3 yrs) (4 yrs) <Cumulative costs> Masonry wall> Normal curtain wall> Low-E curtain wall Normal curtain wall Masonry wall Low-E curtain wall (years) Figure 8: Results for accumulating LCC amount over years. the BIM facilitates calculations of the energy consumption consiering the environmental effects. It is necessary to calculate the fuel consumption for a iverse range of machineries when the LCA is conucte. On theotherhan,itisstillaburenforengineerstoanalyzesuch requirements, because no information on the machinery can be gathere from the BIM results. The information relate to machinery can be supporte by COBIE spreasheets [32]. In aition, for a quantity surveying task, it is common to use a margin to make the results of the task more ajustable, whereas there is no margin for the quantity calculation results provie by BIM. Therefore, it is important to a such a function to the BIM tool to make it possible to conuct the LCA an LCCA in a more accurate way. Finally, it is necessary to have macro or library functions as a-ons that allow for LCA an LCCA for the BIM in the future. In other wors, if the macro or library functions, which can create the require ata automatically, were ae to the evelope framework, it woul be possible to conveniently gather the iverse ata necessary for implementing the framework. 7. Conclusions This stuy evaluate the usability of BIM to conuct LCA anlccaintheearlyphaseofaconstructionproject.to accomplishthis,(i)themethoologyaninformationneee to conuct the LCA an LCCA were analyze, (ii) mapping between the require information an the information that coul be obtaine using the BIM was conucte, an (iii) an Excel worksheet-base framework was evelope. To ientify the usability of the BIM to conuct the LCA an LCCA, a case application was conucte that analyze three external skin systems for an actual builing. Base on the possible iverse alternatives that were consiere as a result of the characteristics of the early project phase, the BIM an evelope framework coul suggest alternatives with better performance in terms of the economic an environmental aspects. Therefore, if the framework evelope in this stuy is applie, it is expecte to be suitable for making important ecisions in the early phases of a project. BIMwasapplietotheframeworkevelopeinthis stuy to obtain the quantity information an energy consumption of a project. Consequently, it was insufficient to verify the accuracy of the acquire information. Because the accuracy epene on the performance of the BIM software, this stuy i not conuct such verification. Rather, a test of the usability of the BIM an framework was performe. In the future, it will be necessary to evelop a BIM library to help engineers an project managers gather the require information, incluing the LCI DB, to conuct the LCA an LCCA. Conflict of Interests The authors eclare that there is no conflict of interests regaring the publication of this paper.

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