Design Optimisation via BIM Supported MaterialPassports

Stefan Schützenhofer1, Meliha Honic2, Iva Kovacic31,2Institute of Interdisciplinary Construction Process Management - Intergratedconstruction Planning and Industrial Building, Vienna University of Technology3Institute of Interdisciplinary Construction Process Management - Integrated con-struction Planning and Industrial Building, Vienna University of Technology1,2,3{stefan.schuetzenhofer|meliha.honic|iva.kovacic}@tuwien.ac.at

Scarceness of resources, lack of waste sites, dependency on imports, increasingurbanization thus increasing consumption of resources and upcoming of wasteare current challenges in built environment. Reduction of both, energy andresources consumption, should thereby be the primary aims for sustainabledesign. Even though by 2020 70% of the building waste has to be either recycledor reused , resources efficiency is less considered than energy efficiency in thedesign stage of buildings. Previous research has shown, that the generation ofBuilding Information Modelling (BIM)-based Material Passports (MP) ispossible and can for example be used for optimization in early design stages. Inthe current curricula the energy design is well represented in the courses ofbuilding science, however, optimization of resource efficiency and recyclingpotentials are still lacking. The focus of this proposal is the implementation of thedeveloped BIM-based Material Passports in teaching for optimization of designproposals, thus enhancing the awareness for recyclability and reusability inconstruction among students of architecture and civil engineering.

Keywords: BIM in education, Material Passport, Sustainability in education,Environmental sustainability, Integrated Planning

INTRODUCTIONScarceness of resources, lack of waste sites, depen-dency on imports, increasing urbanization thus in-creasing consumption of resources and upcomingof waste are current challenges in the built environ-ment.The Architecture, Engineering and Construc-tion (AEC) industry is responsible for 60% of globalraw material extractions (Bribian et al., 2011), 40% ofCO2 emissions (WGBC 2016) and a significant pro-

portion of waste. In Austria, construction waste ac-counted for about 17% (BAWP 2017) of total wastein 2015 (about 40% of the total amount of waste,if excavated materials are not considered), althoughthere is a strong local divergence here. However, notonly the proportion of ”construction waste” is veryhigh in urban areas but is often but is often similarin size as the mass required for the construction ofnew buildings (Brunner 2011). Reduction of both -

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energy and resource consumption - should therebybe primary aims for sustainable design. Even thoughby 2020, 70% of the building waste (non-hazardous)must be either recycled or reused (EU-WRC 2008), re-cycling is currently a less considered design objec-tive than energy efficiency. Material managementtherefore plays a crucial role in creating a more sus-tainable future. Not only valuable primary resourcesare saved through recycling andcascade use in ac-cordance with the (EU-CL 2015), but the limited vol-ume of landfill space is also preserved. However,the (AWG, 2002), which represents the national im-plementation of (EU-WRC, 2008), only defines a veryvague criterion in this respect to when componentsmust actually be reused or recycled: ”Recyclable ma-terials need to be recovered if this is ecologically ex-pedient and technically possible and if it does notinvolve disproportionate costs.” (AWG, 2002) P. 29,§16 pt. 7.1 (translated to English). Therefore, it isessential to know which materials will be availableand how the Ecological Footprint of these materi-als changes due the use of secondary raw materials.Only through knowledge of the effects of stakehold-ers’ actions a conscious decision-making process ispossible. Therefore, it is essential to impart knowl-edge already during the education of planners, ar-chitects and engineers who are responsible for thecreation of the built environment. Raising aware-ness offers a suitable action at the social level (Filhoet al. 2019; [5]). The research questions that willbe addressed are the degree to which MPs can beused for such optimization and how the optimiza-tion process affects architectural and structural de-sign quality, as well as the cost. Thereby, the researchobjective of this paper is to enhance the awarenessand competences of students from architecture andcivil engineering for recyclability and reusability inconstruction. Through simulation of a design to de-construction process supported by Building Informa-tion Modelling (BIM) in teaching, BIM-based MaterialPassports were used for optimization of design pro-posals. A further expected impact is introducing theknowledge of resource efficiency in architectural and

civil engineering curricula. Therefore, the curriculaof civil engineering, architecture and environmentalengineering were examined and searched for suit-able contents. In a further step, a course, which of-fers students the opportunity to deal with the topic,was established. The examination of the curriculumof civil engineering at the TU Vienna shows one com-pulsory course with explicit teaching content in thebachelor’s programme and four in the master’s pro-gramme, whereby their completion is optional. Thefaculty of architecture at TU Vienna offers bachelor’stheses on this topic, and in the master’s programmealso four optional courses. The environmental engi-neering programme delivers four courses in the bac-calaureate and four in the master’s programme. Dueto the new curriculum of environmental engineeringat TU Vienna, the master’s programme is not acces-sible yet, but will be in one or two years. Measureswhich can be found in the literature include (manda-tory) material documentation, as well as a life cycleassessment / recycling evaluation. In the current cur-ricula the energy design is well represented in thecourses of building science and building physics inboth teaching and research. However, the designtools for optimization of resource efficiency as wellas material and recycling potentials are still lacking.This paper is structured as following: first, a digres-sion of the data and tools used as well as the originof the data is given. This includes which parameters,such as eco- and disposal indicators as well as costindicators for cost calculation, are needed to createa Material Passport For cost calculation, parametersare provided ranging from single element layers andlayer packages, like layers of floor constructions, tofacade elements. Next, it is shown how the calcula-tion process of the Material Passport and cost calcu-lation works, and how their results are linked to ob-tain conclusions about the necessarymonetary inputto improve the sustainable performance of the build-ingmodel. In a further step this is shown through aBIM-model given to the students as an example andanalysing the results afterwards.

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METHODOLOGYThrough research led teaching the students of civilengineeringwill implement BIM-basedMaterial Pass-portswith 5DBIMassessment and conduct optimiza-tion upon delivered predesigns by students of ar-chitecture. Using qualitative evaluation and feed-back,the optimization potentials and design trade-offs will be explored, thereby developing the strate-giesfor recycling and reuse of building elements andmaterials already in the early design stage. Themod-els were created by architecture students in a previ-ous semester. The theme of this coursewas to designa building for social housing, considering aspects ofsustainability, prefabrication and modularity.The useof BIM already during this design process was of par-ticular interest, as it allows to consider how muchwaste avoidance could have been achieved with an-other design. However, the focus of this course isnot only the material optimization, but also the con-sequences on costs. For this purpose, masses andquantitiesare readout from the BIM model, includ-ing all relevant components with their geometric pa-rameters,as well as their material structure and ref-erence quantities such as areas, lengths and num-bersof units. This element/component informationis then combined with the relevant parameters (lifecycle assessment and recycling evaluation - IBO[3, 4];costs - BKI [1]). It is important that suitable materi-als and structures as well as databases are found andthat these areassigned (matched) to the existing datagenerated from the BIM model. Due the lack of dataregarding eco-indicators and disposal indicators ofwindowsand doors in the data sources used , a con-sideration of these parts was not possible. For ex-ample, the influence of replacing plastic windows bywood-aluminium windows can unfortunately not betaken into account.

Data and tools”Material Passports are digital sets of data whichprovide the necessary information about materi-als,products and components for a circular use of.” (BAMB 2019) In order to process planning tasks,

suchas the creation of an MP, or the calculation ofconstruction costs, certain data, such as cost pa-rameter per unit (depending on the planning phaseyou needdifferent parameters) or material parame-ters, like the density, are required. It is importantto have an extensive as possible databases (fromthe same source). Due to different approaches orcalculation models during data collection and thecreation of databases,it should be avoided to usedifferent data sources for the same purpose. Tofulfil the task demanded in this course, necessarydata was collected on the one hand from [4] (Aus-trian Institute for Building and Ecology), more ex-actly baubook-eco2soft [3] for sustainability aspects,and on the other hand for the cost calculationchar-acteristic values from the [1] (Baukosteninformation-szentrumDeutscher Architektenkammern), more ex-actly the data of 2017 for residential buildings.Evenif these data is catptured in Germany, it has beenshown that this data fits good enough for furthercalculation in Austria. Therefore, the different taxlevel unddifferent cost group classification must beconsidered. To generate the Material Passport, thecalculation is based on (EI10 2018b and OI3 2018a),linkedwith the data from [3]. (EI10 2018b and OI3,2018a) are guidelines on how to deal with the datafrom[3], for example which recycling quota must beassignedto the respective disposal indicator. The cal-culation of building indexes like in those guideline-sis waived, but the disposal indicator is applied onbuilding level. Furthermore, in this paper the tota-lamounts of the parameters Global Warmth Poten-tial (GWP), Acidification Potential (AP), and PrimaryEnergy, Non-Renewable Resources (PENRT), as wellas the total mass of waste and recycling material ofthe entire life cycle are described. When looking atthe material results (EI 10 2018b), an evaluation ismade according to the school grading system and acorrespondingrecycling quota. The result dependson how much of the whole building can be recy-cled.The data was provided as the BIM model, in theform of the native ArchiCAD files and in IFC format,atemplate (Excel) for creating and calculating theMP,

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anda template (Excel) for calculating the costs duringthe planning phases (cost framework; cost estimatio-nand cost calculation according to ÖNORM B 1801-1). The data for the creation of the MP can be seen ineco2soft. This is an online calculation tool, in which-components can be created and modelled, thus en-abling the calculationof an entire buildingmodel. Anextensive material database is available, which con-tainsguideline values for general material designa-tions, but also data of explicit products. In the field ofBaukosteninformationszentrum Deutscher Architek-tenkammern, the chapters for ”Wohnbauten”of the2017 edition weremade available in digital form. Us-ing data which is not completely up to date is a com-mon strategy in the field of cost calculation.

Figure 1Workflow for theMaterial Passport

Relevant parametersThe data required from (eco2soft, 2020) are dividedinto the areas of waste and recycling managementrelevant parameters, and life cycle assessment rele-vantones. Information about density and life time ofthe component layers and materials is required for-both areas. Further, thematerial parameters GWP [kgCO2 equ/kg], AP (kg SO2 equ/kg] and grey energy- PENRT [kJ/kg] are required to calculate the envi-ronmental impact. For the calculationof the materialmanagement aspects, the disposal classification isalso necessary. The data used to consider the impacton costs resulting from the optimizationstep ( BKI

2017 Bauteile-Neubau, chapter - Ausführungsvari-anten). This step is only possiblewith cost parametersin a certain level of detail, because with these datathe material change of a single shift can be consid-ered in part. However, since the data for precast andelementary components are not very high, the use ofthe data from 2020 might be more useful.

CalculationMethodologyMP. After determining all necessary data, like layerstructures, materials, ecological data, disposal char-acteristics and others, and matching the materials ofthe databases with thematerials of the BIMmaterials. The scheme of the calculation is level based, wherethe building is divided into four levels: the Building-Level, which consists of the massand the amount ofall materials in the whole building; the Component-Level, which is the sum of all materials existing ina particular component; the Element-Level, whichrepresents materials of one particular element andwhere each element is identifiedthrough the Glob-ally Unique Identifier (GUID a fixed 22 characterlength string) (e.g. “01Storey slab_-Regelgeschoß”),which is automatically assigned in BIM-Software, andthe Material-Level, whereby the mass, type of con-nectionwith the enclosedmaterials and the recyclingpotential is described for one specific layer/mate-rial.The first step is to calculate the mass producedat layer level per unit. For example 14.8 kg/m² fora2cm thick solid parquet layer. By taking into ac-count the existing surface area and service life, themass incurred during construction and the plannedservicelife, for example 100 years, can now be calcu-lated. It must be considered that the life expectancycalculated must be adjusted to reflect reality.This isthe case, for example, if the outer layer has a longerlife than the inner layer. Furthermore,this is also nec-essary for the disposal classification. Bonding, for ex-ample, often reduces the recyclability. Therefore, adowngrading of the bonded layers mustbe carriedout. With the total masses identified in this way, itis nowpossible to determine the future recycling andwastemasses thatwill be produced.The environmen-

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tally relevant emissions result from the use of thesematerials. In a further step, one can see to what ex-tent these emissions areinfluenced using secondaryraw materials obtained from the recycling process(figure 1).

Figure 2Workflow for costcalculation duringthe planning phase

Figure 3Workflow to link theenvironmentalsustainabilitypotential, with thechange ofconsequentenvironmental cost

Figure 4Materialcomposition oncomponent level

Costs. The costs which were used for further consid-eration correspond to a cost calculation. Since datafrom Germany was used and structured accordingto DIN,some adaptations had to be made. The costgroups must be changed and restructured, the valueadded tax (VAT) difference has to be taken into ac-count,and since the data is from 2017, they had to beadjust using a cost index. Even if the data basisis notconsistent here, students are requested to researchnon-existing data concerning refabricationelementsthemselves (figure 2).

Optimization and EvaluationAfter the MP was created and the cost calculationwas made, the MP had to be optimisedand the re-sulting changes were compared to the costs. As sus-tainable aspects were required in the creation of theBIM models, but were not the only focus, there issome optimisation potential. Improvements can beachieved in differentways. For example, by changinga layer thickness, by changing amaterial (e.g. chang-ing from plastic to wooden windows),by changing aconstruction (e.g. changing from bitumen sealing towater-repellent concrete), orthe targeted use of ma-terial according to mechanical aspects (hollow coreslabs, ribbed slabs). Basedon these optimisationpro-posals, an MP-optimised and a cost-optimised calcu-lation can bemade. Subsequently, themonetary useis to be compared with the ecological improvement(figure 3). However, as this is a multi-criteria assess-ment, it is alsopossible that the improvement of oneparameter has negative effects on another.

RESULTS OF THE USE CASEMaterial PassportMaterial EI10. In figure 4 the results of one particularbuilding component is shown. This component rep-resents the ceiling of the standard storey, and thusrepresents aconsiderable proportion of the flat com-ponents. The main structure is a Cross LaminatedTimber (CLT)-plate with a thickness of 18cm. Becauseof the goodperformance of CLT, and the share in thetotal mass of the component (75%), the component

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is performing good as well. More than 50% of the to-tal component masscan be recycled (figure 5). Thisis because of the high amount of wood in this com-ponent. But wood isn´t just performing good underthe aspect of the ability to be recycled,but also theecological performance is good as well.

Figure 5Waste andRecycling mass oncomponent level

Figure 6Materialcomposition onbuilding level

Figure 7Waste andRecycling mass onbuilding level

On Building-level, you can see the big influenceofconcrete structures, as well as cement containingbuilding parts. Just two floors of concrete (cellarand ground floor as well as the balcony structures) incombination with gypsum plaster, which makes therecycling process of concrete more complicate, andthe disposal indicatormust be downgraded, produc-ing half of the building mass, and change the recy-cling rate under 50% (figure 6 and7). Thus, the build-ing has disposal grade 3, according to the disposalindex on material level and adaptation on buildinglevel (figure 8).

Ökobilanz OI3. In figure 9 the results of the life cy-cle analysis (LCA) are shown, whereby the calcula-tion of a single key figure according to (OI3 2018a)waswaived. The scale of the individualeco-indicatorswas adjusted to make the results more transparent.For example, the result ofGWP100 is given in 10 kgCO2equ.

CostsSee table 1 for the results of the cost calculation,structured according to (ÖNORM B1801-1). BWK arethe costs of the physical building, BAK are the costs ofBWK with the costs of for example work you have todo on the building sight to be able to build and cre-ate outdoor facilities. Relevant to link the costs to theMaterial Passport is the BWK.

Evaluation andOptimizationIdeally, an improvement will be achieved in both theeco-indicators and thematerial balance. More essen-tial, however, is that interactions between the differ-ent areas can be shown, depending on the optimiza-tion measures, and based on this a discourse aboutgood and less good, maybe even bad measures be-comes possible (figure 10).

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Table 1Cost calculationresults

Figure 8Disposal grade ofthe building

Figure 9eco indicators onbuilding level

Figure 10multi-criteriaanalysis

CONCLUSIONThe aim of this lecture is to create awareness of thestudents, to the problem of high material consump-tion and lack of waste sites, and the growing impor-tance of doing something against these problems. Inorder to overcome these problems, the use of tech-nical tools such as BIM is suitable for documentingthe necessaryinformation in the construction sectorand for taking optimization steps based on this in-formation.Therefore, during a course the Material-Passport was presented, which shows the informa-tion required to performwhich calculation steps andhowBIM can be used to support this. The optimiza-tion step of the Material Passport and the determi-nationof the conclusion on costs enables not only aholistic view, but also creates an awareness of whichmeasures have positive or negative effects on dif-ferent areas. Since models of students of architec-ture are used as a basis for planning, a situationwhich is common to practice is created and whichshould underline the importance of an integral plan-ning approach. The implementation of the MGP inthis form in teaching is not only an attempt to cre-ate awareness for sustainability aspects already dur-ing the education, but also offers the opportunity togive students an insight into the current state of re-search. In addition, results have shown that creativeapproaches to solutions in theuse of BIM are some-times created in the course. The results of the calcu-lation, especially the costs and improvement of en-vironmental factors, in addition to further data likethe demolition, disposal and recycling costs can beused as an aid to decision-making in future demoli-tionprojects after validation for correctness, and thusbe applied in the implementation of the (ARR 2002)- see above - guidelines. In a further step, the con-sideration of reuse should also be embedded in theprocesspresented, as this is stillabove recycling in thewaste hierarchy. Another suitableuse of the Mate-rial Passport would be to generatea Material Cadas-tre, especially in big cities, becausethere thematerialbalance is mostly given as

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