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 Unmaking  Waste  2015  Conference  Proceedings  22  –  24  May  2015  Adelaide,  South  Australia  

Systems for building and construction waste in virtual and material worlds

Session 8

JunkUp: supporting e-procurement of used materials in the construction industry using eBay and BIM – Tim MCGINLEY

Enabling the Reuse of Building Components: A Dialogue between the Virtual and Physical Worlds – John SWIFT, David NESS, Nicholas CHILESHE, Ke XING and John GELDER

Re-Valuing Construction Materials and Components through Design for Disassembly – Philip CROWTHER

 

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Unmaking  Waste  2015  Conference  Proceedings  22  –  24  May  2015  Adelaide,  South  Australia  

JunkUp: supporting e-procurement of used materials in the construction industry using eBay and BIM

Tim McGinley

University of South Australia, Australia

Waste informatics

Materials are typically sourced in the building industry as new materials in bulk that carry guarantees of safety, quality and delivery. The distributed and diverse origins of used materials means that they do not normally carry these guarantees. This paper proposes an information system to support the procurement of used materials at a scale that is appropriate for construction projects. Used materials are commonly placed on sites like eBay either by businesses or end users. The individual nature of each auction means that it could be difficult to manage and procure multiple items in order to satisfy the quantities, condition and type required by the contractor. Therefore this paper proposes the development of a tool called ‘JunkUp’ that would allow multiple auctions of similar items from diverse sellers to be managed as a single item. Based on this system, In future work, it should be possible to use this tool to test strategies to address the risk to safety, quality and delivery. Which should ultimately lead to the opportunity to increase material reuse (and reduce waste) in the building and construction sector.

Keywords: BIM; JunkUp; IFC; Agile Fabrication Protocol; e-procurement; eBay

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Introduction

Despite a global understanding of resource scarcity, the building industry as a whole, still uses a large majority of new materials in construction projects. This paper proposes an approach to make sourcing used materials more attractive to the construction industry. From a logistics perspective this has been referred to as ‘reverse logistics’ (Barros, Dekker, & Scholten, 1998). Services such as eBay provide methods for consumers to purchase new and used products for building projects from both businesses and individual consumers by specifying eBay categories such as ‘building products / DIY’. In eBay it is possible to purchase building products and specify the quantity required as well as query the dimensions of the available tools. It is also possible to specify the ‘condition’ of the product.

The construction industry is currently going through organizational change due to the implications of implementing BIM (building information modelling) which promises an information model for every component in the building. The current process of searching for individual items and separately arranging the logistics for each item is suitable to the self-builder, but may not be appropriate in medium and large construction projects. Which are more likely to require information rich material (virgin) supply chains over the ad hoc item information provided by eBay for used materials.

Therefore this paper proposes an ‘agile’ approach to material procurement by enabling the materials for potentially each element of the building to be sourced independently from waste, recycled or virgin channels. The paper proposes the creation of an ‘agile’ material system and accompanying digital tool that can be used to search for BIM specified material on eBay. This would enable the adaptation of the building material systems to changes in supply chain availability of virgin materials and ultimately support the procurement of waste materials into the construction of buildings.

To achieve this, it is necessary to propose a material file that holds terms that are relevant to the construction industry and could be used to search databases of materials such as eBay. Based on this file a tool is developed to query BIM materials in eBay’s databases. In future work this could be extended to the development of a web / mobile phone app that could automatically bid and arrange delivery of items within a defined geographical radius of the building site. This would enable a software ‘bot’ linked to a CAD program such as REVIT to propose a building based on local salvaged materials, updating the current bidding cost and availability of the items in real time. The following section explores previous approaches to this challenge.

Background

The architecture practice Superuse Studio (Jongert, 2015) describe reusing materials as ‘harvesting’ waste materials. In two projects in the Netherlands, Superuse Studio used reclaimed materials to create challenging architecture including; Worm, a cultural institution in Rotterdam and espressobar *K, a coffee shop / space station in the foyer of the TU Delft architecture department. Both examples were made from reused materials, espressobar *K used reclaimed airplane seats, washing machine doors and many other materials. However we rarely see this kind of approach in larger construction projects.

There is an interest in the construction industry in the implications of BIM in electronic procurement (e-procurement) for the ‘quantity take off’ stage and efficiencies in cost estimating in large construction projects (Ren, Skibniewski, & Jiang, 2012). It is possible to imagine that projects that implement BIM (building information modelling)

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can handle greater complexity and could support increased risk using e-procurement of materials in the construction industry. It is therefore possible that this could enable improved support for used materials. The challenge is that used materials typically do not have the informational assets required by BIM technologies to achieve their proposed optimizations. At the same time the construction industry is still behind other industries in terms of e-procurement. However (Grilo & Jardim-Goncalves, 2011) argue that Model-Driven Architecture, Service Oriented Architecture, and Cloud Computing offer solutions from computer science to bring the AEC industry up to speed (Jardim-Goncalves & Grilo, 2010). However, even with the implementation of these technologies, BIM uptake has its own organizational, legal and technical challenges (Rezgui, Beach, & Rana, 2013).

Looking at the problem from the end of a building’s lifecycle, Cheng & Ma, (2013) propose a method to use BIM to help the construction and demolition industry to make recyclers aware of the type and volume of material in a building prior to demolition. It is therefore possible that such BIM enabled waste could be reused in new construction. Whilst this is appealing it does not help with the existing non BIM used construction material that is potentially available to construction projects. Dankers, Geel, & Segers, (2014) report that BIM implemented in a web platform with an open standard such as IFC (Industry Foundation Classes) which links to external sources could support lifecycle management of materials in buildings. IFC provides an independent data format to support the sharing of building and material information in the building and construction industry. IFC is used as the basis for OpenBIM (OpenBIM, 2015) IFC has many classes for dealing with materials. OpenBIM has been used in a variety of uses including supporting cost estimation in early stage building design (Choi, Kim, & Kim, 2015).

It is clear that the diverse and unpredictable nature of used materials may be incompatible with BIM technologies. This paper seeks to develop a method to source used (non BIM) materials and using a standard such as IFC develop and apply a pseudo BIM (agile material file) to the used materials based on the information stored on the sellers platform in eBay for instance.

Method

This paper aims to propose an agile material systems file that could be used by an app to query eBay’s databases for used construction materials. This involves the development of two artefacts, the material file and the tool to support the information system. Hevner & Chatterjee (2004) propose the use of design science to develop information systems. Additionally, Peffers, Tuunanen, & Rothenberger, (2008) propose a design science methodology for developing information systems which can be defined in the following stages: problem identification and motivation; definition of solution objectives; design and development; demonstration; evaluation; and finally communication. The problem identification stage has been established in the previous sections. The evaluation stage represents the discussion stage in this paper and the communication stage is this paper. The remaining stages are addressed in the following sections.

Solution objectives

This paper aims to identify an approach to support the procurement of used materials from diverse sources as a viable alternative to the procurement of new material from a

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single supplier in the building and construction industry. The background identified that the IFC standard enables an ‘open BIM’ standard that supports data interoperability between traditional stakeholders in the buildings industry. However eBay is built to describe lots of different items and does not follow BIM standards in its description of items in its building materials / DIY category. Therefore this paper propose the development of a schema to link IFC and eBay using the eBay API. The challenges involved in this work will be identified in this section. Some of will be addressed in this work and the remainder will be highlighted for future work. This paper focuses on supporting the user to identify salvaged building material using eBay’s product database, at a scale that is appropriate to medium size construction projects. This will requires the identification of a material schema modelled on common concepts between the IFC BIM standard and eBay’s existing product definitions that enables the user to identify materials in a different digital environment, such as a CAD package. This requires that the user can:

Aggregate a specified quantity, condition and type of material from multiple eBay auctions in one event.

Therefore this paper proposes the creation of an ‘agile material file’ which supports both IFC and eBay terms. The term agile is used to represent that the file can represent lots of different materials at different conditions and types of material. This file will be tested by developing a web app that uses eBay’s API and the agile material file to identify salvaged materials at a scale appropriate for construction projects. The following section describes the stage to develop a tool to address the identified requirements.

Design and development

The tool needs to work with the agile material schema which in turn should be relevant for both the IFC BIM standard and the eBay API terms. For the tool, eBay provides an API (Application programming interface) that allows software developers to produce software that makes use of eBay’s databases. This should offer the opportunity to source building material from eBay. The tasks involved are captured first in a use case diagram (Figure 1) for sourcing used materials on eBay from multiple auctions in one transaction.

Figure 1: JunkUp use case diagram

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The tasks in the use case diagram (Figure 1) are translated into user requirements for each of the users (Table 1).

Table 1: User requirements based on the use case diagram.

User Requirements

Buyer Capacity to specify the quantity of material required and query the eBay database for the required material (may require multiple auctions)

Seller Uploads the item to eBay using standard interface and eBay terms

This presents several technical and practical challenges including how to capture and ‘translate’ eBay’s existing material descriptions to enable designers to source material from eBay. To address this an agile material (translation) file is proposed in the following sections to enable the easy uploading of salvaged material to eBay and the easy recall of this data from inside (or close to) the designers CAD package. OpenBIM provide an ‘xBIM API’ to enable developers to produce software that is in line with the OpenBIM standards. It will not be possible to fully integrate the xBIM API into this iteration of the research, but this is included in future research plans. The proposed tool application will be called ‘JunkUp’ to emphasise and question the waste status of ‘upcycling’ materials.

Figure 2: JunkUp logo

IFC concepts

For the material file, one approach to address this is to produce an ‘entity relationship diagram’ that describes the relationship between concepts (entities) in a database. This should include concepts from BIM and eBay. The IFC Classes ifcMaterialLayer and

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ifcMaterial are therefore relevant to an approach to identify a standard material file that could be read by the app. These classes and their attributes are described in Figure 3.

Figure 3: Material definitions in IFC

The material system file will need to contain attributes that are of interest to the designer, including the extensive values of depth, height and width as well as a material type. The following section identifies the eBay specific concepts for the agile material file.

eBay concepts

eBay is interesting in helping to investigate the concept of new and used. Whilst as a consumer we frequently see used or new or ‘brand new in box’ as a description. Different categories describe new or ‘usedness’ differently. To get around this eBay uses a conditionID value from 1000 to 7000 (eBay, 2015). Building materials generally fit into the business and industrial category and therefore map to the typical eBay conditionID names.

Table 2: eBay API defintions for item condition (eBay, 2015)

ConditionID Typical Name

Cameras & Photo, Cell Phones & PDAs, Computer & Networking, Electronics, Business & Industrial, Home & Garden, Musical Instruments

1000 New New

1500 New other (see details) New other (see details)

1750 New with defects

2000 Manufacturer refurbished Manufacturer refurbished

2500 Seller refurbished Seller refurbished

3000 Used Used

4000 Very Good

5000 Good

6000 Acceptable

7000 For parts or not working

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Mapping the concepts

The previous two sections identified the component concepts of the agile material file. In response to this, Table 03 attempts to map key concepts from the IFC standard and eBay API (eBay, 2015) to common material concepts using an entity relationship diagram. This provides the relationship between the concepts as well as their attributes. In this way, the IFC standard and eBay API provide a standardized set of concepts (entities) that the agile material system could employ.

Table 3: Agile material file concepts

Concept ifcMaterialLayer ifcMaterial eBay API

name name name

Category Category ?

productType Material name

Description Description

Thickness LayerThickness ?

length ? packageLength

width ? packageWidth

depth ? packageDepth

quantity ? quantity

condition conditionID

location location

Table 03 shows that some concepts are shared across the domains of BIM and eBay. The condition concept would be important in a construction context and future work will attempt to identify a nondestructive method of testing the artefacts before they go into the construction of the building.

Demonstration

The tool is still in development and so no user testing has been carried out at this stage however the proof of concept demonstrated that it was possible to establish links between the IFC and eBay concepts and that these could be developed into tools that the design and construction team could use in the future (Figure 4).

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Figure 4: JunkUp search results

Discussion

The previous section demonstrated that it was possible to map some of the terms from IFC to the eBay API. However the method specified the following solution objective:

Aggregate a specified quantity, condition and type of material from multiple eBay auctions in one event

The mockup’s ability to satisfy the elements of this objective are discussed in the following section. These are reviewed through the embedded links to the top three search results (Figure 5).

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Figure 5: Top 3 search results

Specified quantity

It would be possible to specify a specific quantity of the items on offer. However it is more challenging to specify a square meter age of material for instance due to the textual descriptions on the page or in the title rather than users typically inputting the length width and depth/thickness of the material as discrete values in the auction.

Specified condition

This factor was employed in the original API call:

&itemFilter.name=Condition&itemFilter.value=3000

This was successful in limiting the search results to those that specified ‘used’ in their listing. However it is unclear if listing giving different conditionID (Table 2) would have been missed off the search results.

Specified type

A specific type was not called in this case such as a material, or listing category, as the use of key words is quite effective in identifying building products and general category types such as ‘building material / DIY’ do not help to reduce the number of results in the filter. However in future work the effect of category and material filters and their relationship to their IFC analogues should be investigated in more detail. A limitation of this work is the current reliance on cuboid dimensions that may not represent the ‘form’ of the material. Along with this there are syntactical challenges in the way that the materials are to be described on a system such as eBay. One approach to address the challenges with the ever decreasing cost of LIDAR and 3d scanning technologies would be for the seller, to scan the item and for this digital model of the item to be included with the item. In the same way that eBay currently offers users prefilled values for known items it could be linked to a 3d model database, such as that provided by Trimble (formerly owned by Google) with its 3dwarehouse (Trimble, 2015) technology .

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Conclusion

The main limitation of this paper is that it was not tested in the field, however the aim was not to develop the app, but to propose an agile material system that could support the procurement of used materials from eBay from a variety of sellers at scale. Future work should investigate the potential for a JunkUp seller’s tool for sellers to easily post items that include terms that would be relevant to the construction industry. These terms could possibly be a line of human readable code that could be read by the JunkUp buyer app. appended to a standard description. Feasibility of a second system to enable waste from building sites to be quickly reused by others. It may also be appropriate to develop an app using eBay’s seller API which would enable users to input Agile X specific information into the eBay listing.

Ultimately these tools should link to a digital design environment such as REVIT that can arrange the search results into a ‘super’ component containing individual eBay items that could form a wall, slab or roof item in a CAD program using the IFC schema. This should also be able to identify material clashes and propose the necessary joints and cuts. This future work will be supported by the ‘agile’ material file format proposed here to enable contractors to source salvaged material with minimum risk to the project from automated third person services such as eBay. Based on the evaluation of the tools in this paper, the availability of additional APIs such as xBIM’s open source BIM development API and eBay’s API appear to be appropriate technology candidates for this important work.

References

Barros, a. I., Dekker, R., & Scholten, V. (1998). A two-level network for recycling sand: A case study. European Journal of Operational Research, 110, 199–214. doi:10.1016/S0377-2217(98)00093-9

Cheng, J. C. P., & Ma, L. Y. H. (2013). A BIM-based system for demolition and renovation waste estimation and planning. Waste Management, 33(6), 1539–1551. doi:10.1016/j.wasman.2013.01.001

Choi, J., Kim, H., & Kim, I. (2015). Open BIM-based quantity take-off system for schematic estimation of building frame in early design stage. Journal of Computational Design and Engineering, 2(1), 16–25. doi:10.1016/j.jcde.2014.11.002

Dankers, M., Geel, F. Van, & Segers, N. M. (2014). A web-platform for linking IFC to external information during the entire lifecycle of a building. Procedia Environmental Sciences, 22, 138–147. doi:10.1016/j.proenv.2014.11.014

eBay. (2015). eBay API Program. Retrieved from https://go.developer.ebay.com/

Grilo, A., & Jardim-Goncalves, R. (2011). Challenging electronic procurement in the AEC sector: A BIM-based integrated perspective. Automation in Construction, 20(2), 107–114. doi:10.1016/j.autcon.2010.09.008

Hevner, A., & Chatterjee, S. (2004). Design Science Research in Information Systems. In A. Hevner & S. Chatterjee (Eds.), Design Research in Information Systems (Integrated., Vol. 22, pp. 9–23). Boston, MA: Springer US. Retrieved from http://www.springer.com/business+&+management/business+information+systems/book/978-1-4419-5652-1

Jardim-Goncalves, R., & Grilo, A. (2010). SOA4BIM: Putting the building and construction industry in the Single European Information Space. Automation in Construction, 19(4), 388–397. doi:10.1016/j.autcon.2009.11.009

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Jongert, J. (2015). SuperUse Studios. Retrieved from http://superuse-studios.com/index.php/category/materials/

OpenBIM. (2015). OpenBIM: The open toolbox for BIM. Retrieved from http://www.openbim.org/

Peffers, K. E. N., Tuunanen, T., & Rothenberger, M. A. (2008). A Design Science Research Methodology for Information Systems Research. Journal of Management Information Systems, 24(3), 45–77. doi:10.2753/MIS0742-1222240302

Ren, Y. ., Skibniewski, M. J. ., & Jiang, S. . (2012). Building information modeling integrated with electronic commerce material procurement and supplier performance management system. Journal of Civil Engineering and Management, 18(February 2015), 642–654. doi:10.3846/13923730.2012.719835

Rezgui, Y., Beach, T., & Rana, O. F. (2013). A Governance Approach for BIM Management across Lifecycle and Supply Chains Using Mixed-Modes of Information Delivery, (February 2015), 37–41. doi:10.3846/13923730.2012.760480

Trimble. (2015). 3d Warehouse. Retrieved from https://3dwarehouse.sketchup.com/

 

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Unmaking  Waste  2015  Conference  Proceedings  22  –  24  May  2015  Adelaide,  South  Australia  

Enabling the Reuse of Building Components: A Dialogue between the Virtual and Physical Worlds

John SWIFT, David NESS, Nicholas CHILESHE, Ke XING and John GELDER

University of South Australia, Australia

This paper examines the potential for, and attendant impediments of, connecting the virtual and physical worlds, thus enabling the reuse of building components, thereby reducing waste, energy, emissions and cost. It outlines how this may be achieved by the exchange of data between building information models (BIM) and radio-frequency identification (RFID) tags. Whilst BIM and RFID are both established technologies, they have only been employed in the construction sector for transport to site and for onsite tracking of components, rather than for monitoring along the life-cycles. RFID tags are particularly suited to act as an insitu and physical re-writable repository for data such as year and place of manufacture of components, for physical properties, ownership, life history, embodied energy and carbon footprint. Other AutoID technologies such as bar codes only offer read-only information. Access to this information is important for those considering building material reuse, especially as warranting performance history often presents a significant barrier to the reuse of building products. Of course the BIM can hold this information too, and is re-writable, but it isn’t in situ or physical. The proposition that BIM can communicate with RFID via a shared database is investigated and the findings reported. Once this can be demonstrated successfully, it becomes possible for data on physical components (captured by RFID tags) to be interrogated and re-written via a BIM over their lifecycle. Consequently, this facilitates many potential waste elimination or minimisation applications. For example, a building owner may maintain an ongoing ‘health check’ of all the components of a building, structure or facility, for asset management purposes. With regards to ‘unmaking waste’, it becomes possible for an architect or engineer to reconfigure the components within the BIM. Furthermore, via the internet, a designer of another new building may be able to ascertain the availability of building components within the vicinity (in buildings being or about to be dismantled), to assess their properties and suitability, and to be able to import these into a BIM for the new structure. This method should advance a more sophisticated and informed decision-making process, so that the reuse of existing, relocated components may be weighed against the procurement of new components, using parameters such as cost, transport, embodied energy and carbon footprint. This paper also examines how the integration of BIM and RFID technologies may benefit the building sector financially, the types of structures and materials where it may have most application (e.g. demountable, modular steel industrial sheds), the barriers to its success and the kinds of data that would be most appropriate to record.

Keywords: Reuse; Building Components; Connecting BIM and RFID; Data Sets

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Introduction

This paper examines the potential for connecting the virtual and physical worlds to aid reuse of building components, thereby reducing waste, energy, emissions and cost.

The virtual world as used in construction is increasingly being represented by Building Information Models (BIM) as outlined in Azhar (2011) and items in the physical world (predominantly used in logistics) by Radio Frequency Identification (RFID) tags as outlined in Bolic et al. (2010). However until recently, little research has been undertaken into connecting BIM and RFID for modelling of components along the lifecycle. To date, most of the connections between RFID and BIM have been to aid the onsite construction process. However, research into the connection between these technologies has begun to attract some attention, the most relevant being Motamedi and Hammad (2009), Motamedi et al. (2013) and Hinkka and Tätilä (2013).

This research is bounded to steel beams because of their durability, suitability for disassembly and reuse, high embodied energy and to promote the use of calculations as a comparative exercise (due to the availability of reliable data). Though 85% of steel is recycled, this process is highly energy intensive and there is a relatively low level of reuse of steel components (Steel Stewardship Forum 2011) (SSC 2012). As BlueScope Steel (2012) acknowledged, “reuse is the ultimate in recycling, no reprocessing energy is required: the components is simply moved from one location to another”.

In Ness et al. (2014), members of the research team illustrated that, when configured into a cohesive system, a series of existing technologies may facilitate disassembly, take back and reuse of steel components. Connecting BIM with RFID tags during the occupancy phase could enable designers, contractors and others to know the whereabouts, appropriateness for reuse and service history of disassembled components. This could enable the purchase or trade of these components using an internet-based exchange or sale. The properties held on these RFID tags could be imported into models for new buildings at the design stage using Industry Foundation Class (IFC) protocols (BuildingSMART 2015).

One of the most critical and potentially problematic challenges lies in the retrieval and synchronisation of data between the physical (RFID tags) and their corresponding entries in the BIM. Accordingly this research considers the major impediments to the seamless flow of data between BIM and RFID tags:

• Identifying the relevance of the data set to relevant stakeholders.

• The method of data transfer.

• Interoperability of the data.

This paper reports upon this research in progress, and is structured as follows. After enlarging upon the background to the project, the methodology is described. A ‘steel beam property set’ is then established, setting out the range of possible data describing the properties of a steel beam. This data is then analysed to determine the key data influencing a decision on reuse or new procurement. The last section explores the means of integrating such data within a BIM framework to assign object attributes.

Background

There is an emerging theme of wireless connectivity of consumer durables, which has become known as the internet of things (IOT) and is now gaining acceptance with logistic organisations as an aid to efficiencies (Gubbia et al. 2013). If we consider the

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construction sector as partially a logistics enterprise, then the use of logistic tools from external industries and services could be employed to aid construction in new ways.

The steel industry is responsible for 6.5% of Global Greenhouse Gas (GHG) emissions, and 51% of that steel is used for construction. There is estimated to be a 20% increase in the ‘very heavy’ use of BIM in projects from 2013 to 2015 (McGraw Hill 2014, 9). .

A system which can integrate both BIM and RFID would be of use in decision making in construction.

It is expected that this research will initially be most applicable to buildings that are modular, prefabricated and demountable, or that employ a repetitive structural design. However, as envisaged in Ness et al. (2014), greater industrialisation of the building industry, including adoption of the principles of ‘design for disassembly’, ‘open building’, and ‘smart building’, may increase take up of these approaches.

RFID is one of a range of generic technologies used to automate identification of objects (to reduce data entry time and errors). The technologies in this range are termed ‘automatic identification’ or AutoID. RFID is an AutoID technology and can be broadly divided into three categories:

• Active (fully battery powered) tags.

• Semi-passive tags which use batteries to hold data but use reader-derived power to communicate.

• Passive tags which use only the power provided by the reader to operate.

The research proposition is based on the use of passive RFID tags applied to steel beams.

Research Objective

This research forms the first phase of a more extensive project, and aims to test the proposition that data RFID tags may be synchronised with data in a BIM, and vice versa, over the building lifecycle. This part of the research is concerned with identifying data sets that may be most useful.

The research will also examine the reuse of steel building components and illustrate potential savings in waste, energy, and cost. It also lays a logical foundation for the ‘live’ phase of the research.

Research Method

Given the funding restraints and difficulty in accessing a physical structure, the research team decided to initially demonstrate the feasibility of connecting BIM and RFID and define an appropriate data set to underpin further iterations of the research.

Firstly, to determine the range of possible data associated with such a steel beam and its RFID tag, a ‘steel beam property set’ is established. Secondly, the key data influencing decisions on reuse or new procurement is defined. Finally, a systematic approach has been taken to define a property set for a steel beam and the business case calculations have been based on this.

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Steel Beam Property Set

Primarily, every object will have a parent object. Following the Uniclass 2015 classification system schema (aligned to ISO 12006-2:2015), for Products the parent object will be a System. For a steel beam this might be the Structural steel floor framing system. This System will have properties of its own, some of which the beam should inherit, such as minimum required durability.

Second, every object is a member of a class of like objects. This can be assigned to all objects in its class and so it is not project-specific.

Third, every object is of a type. A particular beam could be a ‘hot rolled steel universal beam’, along with many others in the project. In the project specification there would be a clause describing this type. The specifier might model all such beams as being just the one type, with different designations (e.g. 610 UB, 150 UB) being dealt with as ‘instance variants’. Or, the specifier might model beams with different designations as beams of different types. In this case, designation would not be an ‘instance variant’. This choice in modelling is project-specific, so type is necessarily project-specific.

Many countries have national master specification systems, including NATSPEC BUILDING in Australia, NBS Create in the UK (being aligned to Uniclass 2015) and MasterSpec Comprehensive in the USA. These contain standardised library type clauses for objects of various classes, which specifiers can adapt for project use.

Other type properties include the identity of the manufacturer (e.g. OneSteel or BlueScope), the standard (in this case, AS/NZS 3679.1:2010), certification (e.g. ACRS or Responsible Steel), and various sustainability attributes such as non-renewable material resources depletion and non-renewable energy resources depletion.

Fourth, every object is an instance of a type. There might be just the one instance, or there might be hundreds of them. Each individual beam will have a UID (Unique ID). Each beam would also have a unique geometry (though of course there might be a row of beams in a gridded structure with identical lengths and end-conditions), a unique location, and unique loadings. Properties modelled as unique to an instance are ‘instance variants’, a well-known example being door signage.

Instances are project-specific, but their general modelling can be standardised through national BIM libraries, such as the NBS National BIM Library in the UK (2015), Autodesk Seek (2012) in the USA and the BIM-MEPAUS (2014) library in Australia.

Finally, phase properties can be assigned to every instance of a beam. This might include the identity of the installer and the date installed etc. This gives a history of the beam through its life cycle.

Data Exchange

The virtual world precedes the physical, but during their co-existence the two worlds should develop in parallel, so they agree with each other. This means that the BIM and the RFID tags need to ‘talk’. Objects in the physical world typically display some properties, such as a stamp showing the manufacturer and the type of section. However, by attaching an RFID tag to a steel beam, many more properties can be handled. These properties should be standardised in the project specification, rather than left to each manufacturer or supplier to devise.

Hence model will record automatically, as it is developed, the identity of the person changing the model and the date the change was made. This metadata can be used for

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quality control and subsequent calculations, and should also be uploaded to the RFID tags.

For steel beams, potential re-users will be interested in some properties rather more than others. They will want to know its size and its structural capability, but they may have no interest in its embodied energy or its design history, making the decision about information stored on the tag a difficult proposition.

Similarly the needs of future interrogators will have to be foreseen, which is problematic. However, subsequent data can be added to the RFID tags if there is sufficient capacity and the facility to over-write, ideally automatically.

The model does not hold data sets that are needed to support calculations, e.g. for embodied energy or cost rates. Nor will the RFID tags.

It is more likely to transpire that a UID be held on a tag and that information alone is linked to the BIM dataset as a redundancy.

The data might change because the physical project has changed, e.g. a beam has been cut or moved. If the RFID tags and the model can communicate bi-directionally, such changes made to one will automatically change the other.

The data might change all by itself. For example, a cited standard may be superseded, a manufacturer may go out of business, a design regulation may be modified, and the building owner may change. The model and the tag should change accordingly. This is a major data maintenance issue.

At the end of a project’s life, the disassembled systems and products will be dispersed and lose any connection they once had with the BIM. The BIM might be purposefully or accidently erased, or archived (e.g. by the UniSA Architecture Museum). For each object the project data, whatever it is, will then be held only in the RFID tags (Table 1).

Table 1: Types of tag usage

Data Use in Decision Support

As discussed in the previous sections, the information stored in and retrieved from tagged structural steel components can comprise their types, locations, original manufacturers, production and logistics processes, construction and maintenance methods, and other accumulated data from various handlings over the life-cycle. This data is managed, recorded, and encoded by different players at different supply chain stages from production to use.

By interrogating and incorporating such data into BIM, additional functionality is provided, which can support decision making on reuse of steel elements, with the confidence that they are fit for the intended applications and net savings could be made in both financial and environmental senses.

Simple tag Over-writable tag Over-writable tag with GPS

Basic original information

ü ü ü

Expanded and historical information

ü ü

Sense of ‘self’ ü

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Figure 1 illustrates the data logic that can support the assessment and decision making.

Figure 1: Data logic for steel reuse decision support

To be functionally reusable, firstly a structural steel component has to be of correct type (e.g. hot-rolled steel universal beam) and geometries (e.g. 610UB/607 x 228 mm). Although a steel component may meet the functionality requirements, its physical fitness for reuse also needs to be verified as this may change over time, which is defined as the state of reliability. Essentially, the major determinants for the level of physical fitness are material degradation and structural fatigue.

Upon the demolition of a building, a key factor for deciding whether certain structural members are to be retrieved intact for reuse or dismantled for disposal is the associated environmental implications, or environmental loads. This is of particular concern when a project is for design and construction services with the requirement to minimize the environmental impacts of a new building development. For any individual

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steel member, the direct total environmental load, e.g. waste or carbon footprint, related to its reuse or recycling can be assessed as Eq.1.

𝐸𝐿!"!"# = 𝐸𝐿!" +𝑚!𝛼 𝐸𝐿!" + 𝑑 ∙ 𝐸𝐿! + 𝐸𝐿! +

1 − 𝛼 𝐸𝐿!" + 𝑑′ ∙ 𝐸𝐿!! + 𝐸𝐿!" + 𝐸𝐿! (1)

𝐸𝐿!"!#$: total embodied environmental load 𝐸𝐿!": embodied environmental load of the original steel member 𝐸𝐿!": unit environmental load of disassembly/deconstruction per kg 𝐸𝐿!, 𝐸𝐿!!: unit environmental load of transportation per kg 𝐸𝐿!: unit environmental load of installation per km,kg 𝐸𝐿!": unit environmental load of dismantling per kg 𝐸𝐿!": unit environmental load of recycling and re-fabrication per kg 𝑚!: total mass of the steel member (in kg) 𝑑,𝑑′: total distance for transport (in km) 𝛼: a decision factor: 𝛼 = 1 for reuse and 𝛼 = 0 for disposal/recycling

Consequently, at the project level, the relative environmental savings can be evaluated by calculating the difference in the total environmental load (∆𝐸𝐿) between two scenarios, i.e. with reuse and without reuse, as expressed in Eq.2 below:

∆𝐸𝐿 = 𝐸𝐿!"!#$!!

!!! !/  !"#$"− 𝐸𝐿!"!#$!!

!!! !/!  !"#$" (2)

𝑖: an individual item of steel component in the building structure, where 𝑖 = 1,… ,𝑛

The data about unit environmental load for production, disassembly / dismantling, transport, and recycling operations can be obtained from relevant life-cycle inventory databases based on the type of steel, the manufacture method applied, and the retrieval method employed.

Similar thinking and methods can be followed for the evaluation of the economic implications, or economic worth, of structural steel components for their suitability to reuse. Considered as an asset after being installed in the building, the economic worth of structural steel components at the time of demolition can be determined in two forms: the direct cost of recovery and the relative economic savings. For the direct cost of recovery, the assessment is based on the total cost of resource use (e.g. labour, energy, and equipment), logistics (e.g. storage, transport, and other handling processes required), and treatments involved for retrieving and reusing a structure member, offset by its salvage or resale value. However, in order to have a holistic view of the costs and benefits of reusing steel components for a new construction project, it is more suitable to use the measure of relative economic savings. The relative economic savings are estimated as the difference between the project scenario with all reused steel components and the scenario that structural members are purchased as new.

Conclusions and Future Research

In this paper we test the proposition that passive RFID tags may be synchronised with data from a BIM, and vice versa. The proposed data stored on the tags includes information for steel reuse decision support, which enables the construction industry to support the decision making process based on the following four key areas: (1) functional reusability, (2) physical fitness, (3) economic value for reuse, and (4)

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environmental advantage. The paper has highlighted the need and potential for connecting the virtual and physical worlds to enable reuse of building components, thereby reducing waste, energy, emissions and costs. The key barriers emerging from this research were mainly technical in nature and concerned the ‘relevance of the data set’ and ‘method of data transfer’.

One possible system of RFID is to use “license plate” tagging systems, which would refer to a URL for up-to-date BIM data. This system would only require low cost passive tags but would require an internet connection to operate. At the other end of the spectrum would be the use of active tags with links to GPS and environmental sensors. These tags would be able to be updated with additional data when necessary, e.g. when loads exceed their design limits or they have been moved.

First, the proposed BIM/RFID integration may assist building owners to develop and conduct a system for ongoing ‘early health monitoring’ from the facilities management and assets management perspective. This health check would be conducted on all components of a building, structure or facility. Second, it may assist practitioners such as engineers or architects in either refurbishment or new build options. When new building is the preferred alternative, the designer could ascertain the availability and appropriateness of building components within the vicinity with onboard properties which could then be imported into a BIM for a new building. Third, this research implies that the key stakeholders within the procurement process will be able to make informed decisions on reuse versus new procurement. Finally, key areas identified from the application of the data logic for steel reuse decision support can be calculated automatically at any given point during the project life-cycle (design, construction and dismantling).

While this study contributes to the integration of BIM and RFID tags within the construction sector, the interpretation of this proposition is subject to several limitations. In future, this research aims to test the applicability of integrating RFID tags and BIM technology in the reuse of building components on real (live) projects. This will demonstrate of how BIM can communicate with RFID via a shared database over the lifecycle. A limitation of the research was the reliance on hypothetical data in the data logic for steel reuse decision support as illustrated in Figure 1. Future research should empirically validate the decision support by using real data. The next logical step in this research is to extend the work done to date into the coding phase of the project.

References

AS/NZS 3679.1:2010 Structural steel – Hot-rolled bars and sections

Autodesk Seek 2012, “Easily find, preview and download high quality BIM models & DWG files”, Accessed July 2012 http://seek.autodesk.com/

Azhar, S. 2011. ”Building Information Modeling (BIM): Trends, Benefits, Risks, and Challenges for the AEC Industry.” Leadership Manage. Eng., 11(3):241–252.

BuildingSMART Australasia. 2012, National Building Information Modelling Initiative, vol 1, strategy

BIM-MEPAUS (2014),” BIM-MEPAUS “, Accessed February 2015, http://www.bimmepaus.com.au/home_page.html

Bluescope Steel. 2012 Accessed July 2012, http://sustainability.bluescopesteel.com.au/reuse

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Bolic, Miodrag. Simplot-Ryl David. and Stojmenovic, Ivan. 2010. RFID Systems: Research Trends and Challenges. United Kingdom :John Wiley and Sons

Gubbia, J. Buyyab, R. Marusica, S. and Palaniswami, M. 2013 “Internet of Things (IoT): A vision, architectural elements, and future directions”, Future Generation Computer Systems vol 29. 7:1645–1660

Hinkka, V. and Tätilä, J. 2013. “RFID tracking implementation model for the technical trade and construction supply chains” Automation in Construction 35:405–414

ISO 12006-2:2015 Building construction – Organization of information about construction works – Framework for classification of information.

McGraw Hill Construction. 2014 Smart Market Report. The Business Value of BIM in Australia and New Zealand

Motamedi, A. Setayeshgar, S. Soltani, M. and Hammad, A. 2013. “Extending BIM to incorporate information of RFID tags attached to building assets” paper presented at 4th Construction Specialty Conference, Montreal Quebec, May 29 -June 1

Ness, David. Swift, John. Ranasinghe Damith. Xing Ke. and Soebarto, Veronica. 2014. “Smart steel: new paradigms for the reuse of steel enabled by digital tracking and modeling” Journal of Cleaner Production Accessed March 2015. http://authors.elsevier.com/sd/article/S0959652614008786

National BIM Library 2015. Accessed March 2015 http://www.nationalbimlibrary.com/

Motamedi, A. and Hammad, A. 2009. “Lifecycle management of facilities components using radio frequency identification and building information model” 14: 238-262 Special Issue Next Generation Construction IT: Technology Foresight, Future Studies, Roadmapping, and Scenario Planning http://www.itcon.org/2009/18

SSC, 2012. “Steel reuse, Sustainable Steel Construction.” Accessed July 2012 http://johnjing.co.nz/green_web/reuse.php

Steel Stewardship Forum. 2011. “Responsible Steel.” Accessed July 2012. http://steelstewardship.com/

Acknowledgments

This paper builds on Ness D, Swift J, Ranasinghe D, Xing K, Soebarto V. (2014), ‘Smart steel: new paradigms for the reuse of steel enabled by digital tracking and modelling’ for Journal of Cleaner Production, and the subsequent successful Zero Waste SA Sustainable Design and Behaviour (sd+b) Centre Research Funding Scheme 2014 program: Tracking and reuse of building components using BIM and RFID. The project team comprises Dr Nicholas Chileshe, A/Prof David Ness, Dr John Swift, Dr Ke Xing and John Gelder.

 

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Unmaking  Waste  2015  Conference  Proceedings  22  –  24  May  2015  Adelaide,  South  Australia  

Re-Valuing Construction Materials and Components through Design for Disassembly

Philip CROWTHER

Queensland University of Technology, Australia

Architecture

The construction industry accounts for a significant portion of the material consumption of our industrialised societies. That material consumption comes at an environmental cost, and when buildings and infrastructure projects are demolished and discarded, after their useful lifespan, that environmental cost remains largely unrecovered. The expected operational lifespan of modern buildings has become disturbingly short as buildings are replaced for reasons of changing cultural expectations, style, serviceability, locational obsolescence and economic viability. The same buildings however are not always physically or structurally obsolete; the materials and components within them are very often still completely serviceable. While there is some activity in the area of recycling of selected construction materials, such as steel and concrete, this is almost always in the form of down cycling or reprocessing. Very little of this material and component resource is reuse in a way that more effectively captures its potential.

One significant impediment to such reuse is that buildings are not designed in a way that facilitates easy recovery of materials and components; they are designed and built for speed of construction and quick economic returns, with little or no consideration of the longer term consequences of their physical matter.

This research project explores the potential for the recovery of materials and components if buildings were designed for such future recovery; a strategy of design for disassembly. This is not a new design philosophy; design for disassembly is well understood in product design and industrial design. There are also some architectural examples of design for disassembly; however these are specialist examples and there is no significant attempt to implement the strategy in the main stream construction industry. This paper presents research into the analysis of the embodied energy in buildings, highlighting its significance in comparison with operational energy. Analysis at material, component, and whole-of-building levels shows the potential benefits of strategically designing buildings for future disassembly to recover this embodied energy. Careful consideration at the early design stage can result in the deconstruction of significant portions of buildings and the recovery of their potential through higher order reuse and upcycling.

Keywords: design, disassembly, reuse, architecture, construction

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Introduction

The construction industry is responsible for or a significant portion of our material consumption and our energy use. This investment in the build environment is however not always a long term investment. In our industrialized societies we are demolishing our buildings after disturbingly short life spans. This demolition, largely driven by economic factors, accounts for a significant portion of our society’s solid waste, which represents not only a waste of material, but also creates significant negative environmental impacts. “A simple and effective measure to reduce the environmental impact of construction is responsible materials management at the construction stage” (Hammond and Jones 2008, 96). If buildings were designed with their future deconstruction in mind we could re-value the materials and components in them, and also recapture the energy embodied within them. This embodied energy of the built environment has been estimated at between 10% and 20% of Australia’s total energy consumption (Haynes 2010).

Waste in the construction industry

Quantities of waste

Globally, the construction industry is responsible for a significant portion of the solid waste stream, typically between 20% and 60%. In the U.S.A. for example 30% of all waste produced comes from the construction and demolition industry (Guy and Ciarimboli 2003, 2). There is no reliable recent data for the whole of Australia; however some recent research suggests that construction and demolition waste represents as much as 69% of all landfill (Li et al. 2013).

While some demolition material is recycled, the rates are low. Recycling rates in Australia range by State from as low as 17% in Western Australia to 79% in South Australia, with a national average of 58% (Li et al. 2013). It is important however to note that the majority of this is low level recycling, with little higher order reuse.

Perhaps the most significant factor in these high rates of waste is the short life expectancy of buildings and their materials and components.

Life expectance of buildings

Buildings are no longer demolished simply because they are old and structurally unstable. Buildings are now demolished for reasons of economic obsolescence, social obsolescence, locational obsolescence and stylistic trends. In the U.S.A. 27% of buildings that existed in the year 2000 are expected to be replaced by 2030 (Guy and Ciarimboli 2003, 2). A study by the Athena institute in the U.S.A. found that 30% of demolished buildings were less than 30 years old (Guy and Ciarimboli 2003, 5).

While this life expectancy of modern buildings is disturbingly short, many parts of the buildings have an even shorter life expectancy; and in some ways this is driving the overall life span down. For example the envelope of the building, its outer skin, is typically only expected to last half or a quarter as long as the building structure, and the services and space fit-outs inside the building are expected to be replaced on an even shorter cycle. These different building layers have distinctly different life expectancies (see Table 1). It is these disparate life expectancies of different layers of the building that are causing such high rates of material waste. Most buildings are still being designed as a single entity as if they will last for centuries with little or no consideration about the potential embodied within their materials and components.

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Table 1: Life expectancy of different building layers, in years

Structure Skin Services Space Building type

100 25-50 25 10 House: timber frame, brick cladding, ceramic tile roof (Fay, Treloar and Iyer-Raniga 2000)

100 25 10-20 4-10 Non-residential Open building (Kendall 1999)

30-300 (typically 60)

20 7-15 3-10 Undefined (Brand 1994)

50 50 15 5-7 Office buildings (Duffy and Henney 1989)

60-100 15-40 5-50 5-7 Office buildings (Curwell 1996)

60 (assumed maximum life)

20 7-15 3-5 Commercial buildings (Storey 1995)

65 65 10-40 5 Office buildings (Howard and Sutcliffe 1995)

50 (assumed maximum life)

30-50 12-50 10 Freestanding singe unit dwelling (Adalberth 1997)

40 (assumed maximum life)

36 33 12 Office buildings (McCoubrie and Treloar 1996)

40 12-30 30-40 8-40 Timber frame, brick cladding (Tucker and Rahilly 1990)

Energy in construction

One significant aspect of these quantities of materials and waste in the built environment is the energy used to create these materials, construct our buildings, and to operate them. “Worldwide, 30-40% of all primary energy is used for buildings and they are held responsible for 40-50% of greenhouse gas emissions” (Ramesh, Prakash and Shukla 2010, 1593). It has been a long held view that the energy used to operate our buildings (lighting, heating, air conditioning, etc.) is the only significant component of their full life cycle energy use; that the energy use to construct them (embodied energy) is very small in comparison. As such, most research into energy efficient buildings has focused on operational energy; however it now seems that “embodied energy consumption may be more significant than previously thought” (Troy et al. 2003, 9).

Operational energy

The operational energy required for any given building is very dependent on the building type and what it is used for, and perhaps more importantly, where the building is located climatically. Worldwide data on the operational energy for office buildings shows a wide range of typical values from as low as 290 MJ/a.m2 to as high as 1,980 MJ/a.m2 (Suzuki and Oka 1998) (Ramesh, Prakash and Shukla 2010, 1598). For residential buildings the values are typically as low as 540 MJ/a.m2 to as high as 1,440 MJ/a.m2 (Ramesh, Prakash and Shukla 2010, 1598). It is important to note that these

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are typical values and do not represent high performance energy-efficient designs or buildings in extreme climatic locations.

The most significant factor in determining operational energy use is typically the climate. It is indeed because much research into building energy consumption has been conducted in the colder climates of northern America and northern Europe that operational energy has been so high, and traditionally been seen as the only significant component of life cycle energy use.

Embodied energy

The embodied energy of a material or product is the sum of all the energy required to produce that material or product. This will include the energy required for; materials extraction, materials processing, transport and direct manufacturing. It also includes part of the energy required to create the buildings and machinery associated with all these steps in processing. Calculating embodied energy for construction materials and components is notoriously difficult and unreliable. Values vary considerably from one study to the next and vary considerably over time; older studies typically providing higher values than more recent research; despite the variances “they can be considered to provide good benchmarks for use in determining the life-cycle performance of buildings” (Hammond and Jones 2008, 89).

For office buildings typical values for embodied energy are in the range of 7,000 MJ/m2 to 17,000 MJ/m2 (Ramesh, Prakash and Shukla 2010). In one Australian study the typical values were measured at being between 8,000 MJ/m2 and 9,000 MJ/m2 (Treloar 1993). For residential buildings the typical values of embodied energy range from 4,000 MJ/m2 (Hammond and Jones 2008, 94) to as high as 14,100 MJ/m2 (Fay, Treloar and Iyer-Raniga 2000, 38). We can also look at how this embodied energy is distributed between the different layers of the building (structure, skin, services and space fit-out), noting that those parts that typically have very short life spans constitute a considerable portion of the overall embodied energy (see Table 2).

Table 2: Typical percentage of embodied energy in different building layers

Structure Skin Services Space Building type

36 31 11 22 House: Timber frame, brick cladding, ceramic tile roof (Fay, Treloar and Iyer-Raniga 2000)

48 29 10 13 Single storey office building (Yohanis and Norton 2002)

33 29 24 14 Commercial building (Atkinson et al. 1996)

39 23 15 23 Single family dwelling (Haynes 2010)

34 36 18 12 Multiple dwelling housing (Thormark 2002)

32 28 26 14 Office building (Cole and Kernan 1996)

36 34 - 19 2 storey office building (Oppenheim and Treloar 1995)

30 - 15 25 Office buildings (Suzuki and Oka 1998)

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Total energy

As previously noted, operational energy is clearly much greater than embodied energy and it has understandably received much greater research attention over the years. However, as buildings become more energy efficient in operation, the significance of embodied energy will proportionally increase. It has been shown previously that in a subtropical climate operational energy is generally lower than in temperate regions of northern America and Europe, so that embodied energy is proportionally greater (Crowther 2006).

Numerous studies in a range of international contexts have calculated that the embodied energy of a building, with a 50 year life expectance, is typically 5% to 20% of total life cycle energy (Ramesh, Prakash and Shukla 2010). But as noted above, for low-energy use buildings, or energy-efficient buildings, embodied energy may be as much as 40% to 60% of total energy use (Thormark 2007). A meta-analysis of the comparative energy use of sixty case studies calculated the embodied energy of conventional buildings at between 2% and 38% of total life-cycle energy, and the embodied energy of energy-efficient buildings at between 9% and 46% of total life-cycle energy (Sartori and Hestnes 2007). Other international studies have shown embodied energy to be as high as 67% of the total life cycle energy (Yohanis and Norton 2002, 77).

Research in Australia has shown that embodied energy is typically equivalent to ten years of operational energy for dwellings and thirty years of operational energy for office buildings (Sattary and Thorpe 2012, 1402); this would equate to 10% and 33% of total life cycle energy over 100 years, or double those percentages over 50 years.

Another study of 25 dwellings in Australia has shown a mean operational energy value of 810 MJ/a.m2 and a mean embodied energy value of 9,900 MJ/m2; showing that over a 50 year life cycle the embodied energy represents almost 25% of total energy (Pullen 2000, 90). Yet another Australian study has shown that embodied energy for residential buildings to be from 20% to 25% of the life cycle energy use (Troy et al. 2003). We can conclude that “embodied energy is significant relative to operational energy” (Fay, Treloar and Iyer-Raniga 2000, 39).

It is worth noting that the direct energy of the actual building construction (operation of machinery and plan on site) is relatively small and has variously been measured at between 6% and 15% of the embodied energy, or between 0.5% and 3% of the overall life cycle energy cost (Fay, Treloar and Iyer-Raniga 2000) (Pullen 2000, 88). Similarly the direct energy for demolition and removal of materials for disposal is typically less than these percentages of total life-cycle energy (Suzuki and Oka 1998). The significance of this is that at such a small percentage, compared to the overall embodied energy, any additional construction energy required to implement a design for disassembly strategy will be far outweighed by the energy recovered from materials and components.

If we combine the life expectancies of different building layers from Table 1 and the typical embodied energy values from Table 2 we can see that with periodic refurbishment the embodied energy over 50 years is a significant portion of total life cycle energy (see Figure 1).

Recycling energy

The reuse of building and construction materials for the same purpose as their original use can save up to 95% of the embodied energy since there is little or no processing involved. The recycling of materials, through reprocessing and remanufacture, is

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usually less efficient; typically saving from 5% for glass, up to 95% for aluminum, with most construction materials in the lower part of this range (Sattary and Thorpe 2012). One study of actual building demolition waste showed a potential embodied energy recovery through recycling of 37% to 42% (Thormark 2002).

Figure 1: Total life cycle energy use over the 50 year life of a typical office building

The ability to reuse materials and components is much more energy wise than recycling. Despite this the majority of materials that are salvaged are recycled or down-cycled not reused. For example, rates of steel recycling in the U.K. and the U.S.A. are 86% and 97% respectively, but with little or no direct reuse (Lee, Trcka and Hensen 2011, 68-69).

One study of life cycle energy use shows that the periodic refurbishment and maintenance of a building, over a fifty year period, can be more than the initial embodied energy (Yohanis and Norton 2002). If the materials and components removed during the refurbishment are sent to landfill then the embodied energy being lost can be more than the initial embodied energy of the building. The potential for recovering the embodied energy through recycling and reuse is significant.

Design for disassembly

It has been shown that a significant hindrance to higher rates of materials and component reuse is the inability to easily and economically disassemble them from each other (Crowther 2009). This is especially true at the junction of the layers; between structure, skin, services and space fit-out. The future capacity for reuse and recycling is being determined at the initial building design stage. If buildings were designed to facilitate future disassembly then higher rates of high-order reuse and embodied energy recover could be achieved.

There have historically been many such buildings designed with future deconstruction in mind, and a review of them has identified a number of principles for design for disassembly (Crowther 2009, 231-235). These principles include:

• Minimise the number of types of materials

• Minimise the number of types of components

• Avoid secondary finishes to materials

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• Use mechanical connectors not chemical

• Use modular design

• Provide adequate access to components • Size the components to suit means of handling • Apply realistic tolerances during manufacture • Limit the types of connectors • Allow for parallel assembly and disassembly • Use lightweight materials and components • Identify points of disassembly

These principles are neither complex nor surprising. What is surprising is how little regard there is in the construction industry for considering these principles as a way to reduce the environmental burden and reduce the material waste in our built environment. If buildings were designed for disassembly the potential for embodied energy recover could be in the order of 25% to 50% of total life cycle energy. Following a strategy of design for disassembly may require additional material and energy input at the initial stages, though as shown, the energy for actual on-site construction is comparatively small. By comparison the potential material and energy recovery is significant. It is also worth noting that such energy and material recovery would come with significant financial savings. Material costs, as a percentage of building costs, vary widely depending on material choice and construction method. It is however reasonable to expect that materials may typically be half of the overall build cost; as such any material and component reuse represents a significant financial saving and well as energy and material saving.

The reuse potential of a material or component is only as good as the initial design is in allowing such recovery. The investment in our built environment can offer returns through re-valuing of materials and components if we are wise enough to consider the reuse potential at the design stage and allow for future disassembly.

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Philip Crowther is an academic at the Queensland University of Technology (QUT). He has qualifications in architecture, film, and higher education. Philip has worked on architecture projects in all the eastern States of Australia and in China. He has taught in all year levels of the architecture program and is currently the Head of the Architecture Department at QUT.