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Integrated design of product lifecycles—The fridge case study
CIRP Journal of Manufacturing Science and Technology 1 (2009) 214–220
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Integrated design of product lifecycles—The fridge case study Alexis Gehin, Peggy Zwolinski *, Daniel Brissaud G-SCOP Laboratory, Grenoble University, 46 avenue Fe´lix Viallet, 38031 Grenoble Cedex 1, France
A R T I C L E I N F O
A B S T R A C T
Article history: Available online 21 June 2009
To help engineering designers understand and translate environmental constraints into effective actions, new methods and tools for engineering have to be developed and used at the product conceptual design phase. Indeed, this design stage is mainly concerned with the actual trade-off among all the constraints, therefore generating more environmentally benign design alternatives. This paper aims at presenting a method to support designers in the definition of the product lifecycle scenario, including component lifecycle scenarios, when designing the elements of the structure of the product. The current design can be continuously assessed by lifecycle analysis (LCA) methods. The main concept used is the lifecycle brick that has been proposed to support both the product model and the lifecycle scenario. The data encapsulated in the model are computed to outcome quantitative contribution to the environment in now classical eco-points. The method is illustrated via a fridge case study. ß 2009 CIRP.
Keywords: Engineering design Lifecycle scenario Environmental impacts Simplified LCA
1. Introduction The future of the next generations lies in our efficiency in reducing the environmental degradation of our planet. The challenge of sustainable development encompasses different actions, among which the reduction of polluting emissions and production of wastes are of primary importance. Engineering and manufacturing are being challenged to create the ‘‘new world.’’ Recent directives in Europe hold the manufacturers responsible for their products even after they are sold, applying the Extended Producer Responsibility principle. Facing the dilemma of being competitive and clean at the same time, industrialists are willing or are forced to take actions to reduce the environmental burden of their activity [1]. The hypothesis is that designing products with an environmental sense of responsibility as soon as possible can make it possible to anticipate more and more demanding regulations [2]. This paper focuses on the product and on its ability to be clean and re-valuable. In order to help engineering designers understand and translate the environmental constraints into effective actions, a methodology that enables the generation of more environmentally benign design alternatives according to LCA criteria [3] has been developed. It is assumed that the focus of designers should be (1) on the entire lifecycle of the product and consequently that they must know more about each phase and (2) on the end-of-life strategies where many gains could be made by reusing components with intelligence. This paper aims at presenting a part of this work using simplified lifecycle
* Corresponding author. Tel.: +33 4 76 82 52 74; fax: +33 4 76 82 70 43. E-mail address: [email protected] (P. Zwolinski). 1755-5817/$ – see front matter ß 2009 CIRP. doi:10.1016/j.cirpj.2009.05.002
impact assessment (LCIA) to assess the environmental impacts (EIs), and emphasizes the concept of lifecycle bricks to structure the product data when designing. This concept supports the development of the adequate product lifecycle model for environmental assessment during the early design phase. This central proposition (Section 2) enables the designer to rapidly formulate lifecycle scenarios and then test them according to LCIA methods. Results can be visualized quantitatively and graphically as well as connected to the elements of the product model. The methodology proposed in the paper is illustrated via the design of a fridge (Section 3). 2. Method for the product Lifecycle environmental assessment during the conceptual design phase The perception of sustainable products has changed over the past few years, sliding from a cradle-to-grave approach to a cradleto-cradle one [4,5]. Closed-loop industrial systems imply that OEM do not only take care of product manufacturing and use, but also of how products can be taken back and treated at their end-of-life or re-included in new lifecycles [6,7]. Therefore, the role of designing the products whose components might be reused, remanufactured or recycled is of major importance [8,9]. To keep and reuse the high manufacturing added-value embedded in each element of a product when it is discarded, the EoL strategy of the whole product depends on the most appropriate EoL scenario of each product element. Consequently, the product EoL strategy should be a mix of the three EoL scenarios: reuse, remanufacture, and recycle, and is named 3R strategy in the paper. Unfortunately, existing engineering design methodologies do not take into account the fact that products might go through several usage cycles, yet this
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aspect will condition the design of the product [10] as well as its environmental performance [11]. It has also been said for many years that the available design methodologies cannot efficiently support the environmental perspective while still being in the conceptual design phase [12]. Indeed - Guidelines have been developed to guide designers’ decisions in the early design phases. These guidelines are well adapted to the conceptual design phase, used as drivers for a sustainable design, but have failed to return usable quantitative indicators that could be analysed and balanced with the other design indicators at this stage of the design project [13]. - Lifecycle analysis (LCA) to evaluate the environmental impacts of the product [14–16] and design for environment (DfE) tools [17,18] are frequently used late, during the detailed design phase, only when a large set of data are available (components, weights, material, joining techniques, manufacturing processes, . . .) but also when modifications to the product are difficult to realize without a large waste of time and money [19,20]. Our general vision on design methodology is to run a situationbased approach [21] that focuses on the negotiation of strategies and their impacts on product characteristics throughout the product development phase. It is assumed that negotiations between product engineers and end-of-life strategy engineers can be prepared, performed, and then controlled. For that reason, an innovative way of modeling products during the early design stage has been proposed. First of all, it allows taking into account 3R strategies and consequently the product lifecycle over several usage cycles. Second, this model makes it possible to create product lifecycle scenarios suitable for quantitative environmental assessment. Third, it has been adapted to be used by practitioners. The proposed methodology is based on The ‘‘lifecycle bricks’’ to support designers in building lifecycle scenarios. A method to assess sustainable lifecycles from an environmental perspective. 2.1. The lifecycle bricks to support designers in building lifecycle scenarios As described in the introduction, there are large strategies that allow retention of the added value of product components after
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their usage cycle, such as recycle, remanufacture, and reuse [22]. While developing the product, designers need to quickly determine the lifecycle strategy applied to each component, and therefore require some robust indicators to select the most appropriate [23]. From an environmental point of view, it is thus necessary to consider not only the initial use phase of the product, but as many phases as the product can have. The lifecycle of the product is said to be closed (closed-loop) though, and the product will ‘‘live’’ through as many loops as possible before being finally removed from the manufacturing world. In order to do that, a representation of the product lifecycle is needed. The product lifecycle is classically represented as a sequence of phases, namely (and to make it simple) material extraction, manufacturing and assembly, use and end-of-life that make sense for environmentalists. Frequently, the LCA experts realize the analysis from the product bill of materials. They list the components of similar materials and calculate the sum of the mass for each material present in the product. Then, they carry out the analyses on these aggregated values without being able to know thereafter the exact contribution of each component. To avoid these aggregated results that are not usable by designers to improve the components and products design, the classical lifecycle representation has been adapted (see Fig. 1): - More lifecycle phases have been defined, depending on the designers’ expertise in being able to consider the real causes of the environmental impacts. So, eight generic phases have been used to model the lifecycle from a designer’s point of view: (1) material extraction and transformation, (2) component manufacturing and assembly, (3) component distribution, (4) product assembly, (5) product distribution, (6) product use, (7) product take-back, (8) component end-of-life. - Two different levels have been highlighted: the product level and the component level. Indeed, recovery strategies belong to the component lifecycles. Thus, when developing the product, designers have to determine an EoL scenario for each component, as components do not all have the same ability to be recovered at their end-of-life. The different flux of components and products are represented by arrows in Fig. 1. The possible ways or strategies are not exclusive and have to be precisely defined for each component. It is quite frequently the case that a part of a component in end-of-life can be remanufactured whereas the other parts of the component are recycled.
Fig. 1. The Lifecycle representation.
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The model proposed is based on the lifecycle brick concept. The objective is to help designers to rapidly build lifecycle scenarios that can be environmentally assessed, so that new design alternatives can be generated and then tested. A lifecycle scenario is composed of a sequence of lifecycle phases represented by lifecycle bricks for the products or for the component. The lifecycle bricks were built with the aim of delivering relevant results to designers who are not environmental experts: this is directly linked to the engineering design feature of the product and its lifecycle. The bricks give information to enable evaluation of the environmental impact of the product components for each lifecycle phase of the product. The objective is to allow designers to have access to sufficient detailed information that can be usable in analyzing their design choices of materials, manufacturing processes, logistics, usage, end-of-life, . . . So, a lifecycle brick has two dimensions: a lifecycle phase and a product/component dimension. It addresses Components for the phases while the product is disassembled (number 1, 2, 3, and 8 on Fig. 1). The whole product for the phases while the product is assembled (number 4, 5, 6, and 7 on Fig. 1). The lifecycle brick is defined as a black box containing the necessary data for the calculation of environmental impacts according to the lifecycle impact assessment methodology. Each brick contains the following information (see Fig. 2): An identifier, based on the name of the lifecycle phase and the component or product name. Data related to the components or product and relevant to the lifecycle phase: mass, type of material used. The processes related to the lifecycle phase, and for each of them the consumption and impact towards the environment. The results of the environmental impact assessment after they have been evaluated. They are stored as impacts by categories, normalized impacts, and weighted impacts. As illustrated in Fig. 2, the lifecycle brick is a means of linking product design data to expected lifecycle strategies while giving an environmental score that depends on these two aspects. While the product is being designed, four product-level bricks are compulsorily created, and four component-level bricks for each new component are created. Designers are asked to provide the data related to each brick: the more precise the information, the more detailed the lifecycle models. When designers need to make a design choice, or whenever a brick is modified, the environmental assessment is made and the environmental criterion is added to the decision process. Thus, designers can work on design alternatives at both the component and product levels, while having access to quantitative indicators related to the environment, and taking into account the overall lifecycle of the products.
2.2. The environmental assessment of sustainable lifecycles The main objective in defining the design methodology within the framework of sustainable development was that designers could take actions on component end-of-life strategies [12]. Indeed, this would certainly make them act on other lifecycle phases [24]. During the design process they develop many lifecycle options and thus need to determine the best one, or at least not the worst one, for the environment. So, the proposition is to assess lifecycles for a specific design. Designers can use the lifecycle bricks to build lifecycles, and a method has been developed that makes it possible to model closedloop systems using the brick concept. So, the bricks being defined let us explain the rules for building lifecycles of closed-loop systems (Fig. 3): A lifecycle is created as soon as the first component is created. The four product-level bricks are built as well as the four component-level bricks. The environmental impact of the product is the sum of the impacts of the bricks (only for weighted impacts or normalized impacts for certain methods). Each time the designer creates a new component, four new bricks of the component level are created and new impacts are added to the former ones for each lifecycle phase and for the whole product. For closed-loop strategies (3R strategies), designers have to evaluate ‘‘u’’ the number of usage cycles that the component can support at its maximum, and the component end-of-pipe strategy to take place at the end. Because the strategy cannot certainly be 100% efficient due to the recovering process capability (quality of take-back parts, percentage of products recovered, efficiency of the remanufacturing process, . . .), endof-pipe scenarios have to be determined as well as the estimation of the percentage of components that will be effectively reused/ remanufactured. Once the model is ready for calculation, the environmental impacts are determined. Then, the impacts are brought back to one single usage cycle so that the designers can compare the different lifecycles alternatives they have envisioned. The variables and rules developed in order to build the lifecycle model of closed-loop systems are described as follows: Notations: i is used to identify the component (1 to n components). ui is the number of usage cycles (loops) that the components i can support at maximum. xi is the percentage of components that can be effectively reused, remanufactured, or recycled in the loop, at the end of the usage phase. In a first approach, it is assumed to be the same at every loop (same end-of-life option and same percentage). j is used to identify the lifecycle phase: 8 j = 1 for the material extraction and transformation phase. 8 j = 2 for the components manufacturing and assembly phase. 8 j = 3 for the components distribution. 8 j = 4 for the components end-of-life phase.
Fig. 2. Description of the data stored in a lifecycle brick.
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Fig. 3. Product lifecycle construction.
Bi,j represents the environmental impact of the component i for the lifecycle phase j (environmental impact of the brick (i,j)). EoUi represents the end-of-usage option for the component i (reused, remanufactured, recycled). EoLi represents the end-of-life option for the component i (recycled, incinerated, landfilled) and for the percentage of components that cannot be reused at the end of the usage cycle. IEmati, IEmani, IEdisi, IEEoLi, represent the values of a component environmental impact, per unit of usage (the corresponding impacts of each loop are added and the result is then divided by the number of loops). IEmat, IEman, IEdis, IEEoL, represent the environmental impact of the product for each lifecycle phase, per unit of usage. Rules: (1) If the component i is recycled in a closed-loop system (it is assumed that the recycled material is used to manufacture the same type of components) or remanufactured, or reused, then for each usage cycle between 2 and ui and for the percentage of recovered product, the material stage impact is set to zero. So, the value of the material phase environmental impact, per unit of usage, for the component i, is IEmati ¼ Bi;1
f1 þ ðui 1Þð1 xi =100Þg ui
(2) If the component i is remanufactured, or reused, then for each usage cycle between 2 and ui and for the percentage of recovered product, the manufacturing impact is set to zero. In this case, the value of the manufacturing phase environmental impact, per unit of usage, for the component i, is if EoUi ¼ freused or remanufacturedg IEfabi ¼ Bi;2
f1 þ ðui 1Þð1 xi =100Þg ui
If the component i is recycled in the closed-loop system, the value of the manufacturing phase environmental impact, per unit of usage, for the component i, is if EoUi ¼ frecycledg
IEfabi ¼ Bi;2
(3) It is assumed that the distribution impact is the same whatever the chosen strategy for the component. So, the value of the distribution phase environmental impact, per unit of usage, for the component i, is IEdisi ¼ Bi;3 (4) If the component i is remanufactured, or reused, the environmental cost of these processes are included in the end-of-life environmental impact. So, the value of the
end-of-life phase environmental impact, per unit of usage, for the component i, is ½fðui 1Þ ðBi;4 ÞEoU xi =100g i
IEEoLi ¼
þf1 þ ðui 1Þð1 xi =100Þ ðBi;4 ÞEoL g i
ui
ðBi;4 ÞEoU returns the environmental impact corresponding i to the reuse case or to the remanufacturing case or to the recycling case. ðBi;4 ÞEoL returns the EoL environmental impact correspondi ing to the recycling case or to the incineration case or to the landfill case. (5) The environmental value of a component per unit of usage is calculated by summing up the environmental impact of each brick of a componentIEi ¼ IEmati þ IEmani þ IEdisi þ IEEoLi (6) The environmental value of a lifecycle phase per unit of usage for the product is calculated by summing up the environmental impact of each brick for the corresponding lifecycle phase. X IEmati IEmat ¼ ð1 ! nÞ X IEman ¼ IEmani ð1 ! nÞ X IEdis ¼ IEdisi ð1 ! nÞ X IEEoL ¼ IEEoLi ð1 ! nÞ This tool makes it possible to build a product lifecycle very promptly, even with rough data, which the designers upgrade step by step. As soon as they need an evaluation of the environmental performance, they can launch the calculation and compare two design alternatives. The following section describes a case study of a fridge design process. 3. Case study: the Use of the 3R method during the design process of a fridge 3.1. The product description and the first environmental evaluation The product chosen for illustrating the methodology is a classical refrigerator with a 200 l storage capacity for the cooling volume and 80 l for the freezer. The energy consumed per year is limited to 200 kWh and is a mix of French energy. This refrigerator satisfies the needs of three to five persons for a lifetime of 10 years. Depending on the numerous legislative constraints, the overall optimization of this product from an environmental point of view is necessary. At the beginning of the conceptual design phase, four main components (a main component is a functional feature that will finally be implemented in several parts and physical components) have been identified: the body, the cooling system, the storage boxes, and the packaging.
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218 Table 1 Component data (extract). Component
Part
Material (gr)
Process
Door
Body Accessories Foam Handle
Steel (4000) ABS (1800) Foam (1500) Al (250)
Stamping Thermoforming Injection Extrusion
Casing
Ext surface Compressor body Foam Tracks
Steel (500) ABS Foam (4700) Steel (1000)
Stamping Thermoforming Injection Rolling
Lighting
...
During the project, designers went about proposing solutions. They proposed different parts and components for implementing each main component, and established the data necessary to construct the lifecycle bricks. For each component, as for the door, the casing . . . it is necessary to precisely determine the material, along with the estimated weight and the possible manufacturing process (Table 1). In our study, the data is derived mainly from an existing EDIP case study [3]. The reference lifecycle is when all the components are recycled at their end-of-life after one usage cycle. The environmental impact for this reference lifecycle will be compared with the values obtained for the other lifecycle propositions as evidence of their environmental efficiency. Table 2 shows the environmental impact (in eco-points) of the fridge partially described in Table 1. Horizontally are the main components of the product; their scores are related to their design at the moment the calculation was generated. Vertically are the lifecycle phases attached to either the sub-assembly (C for component) or the product itself (P): material extraction (Mat, only for C), manufacturing (FabAss, only for C), distribution/logistics (Dis, for C and for P), assembly (Ass, only for P), use (use, only for P), recovery (Rec, for P and for C) including the end-of-usage lifecycle of each component; in this study all components are recycled at their end of life (EoL_Rec, only for C). In the example of the door (Table 1), the necessary data contained in the brick enables calculation of the score for the normalized and weighted environmental impacts: stamped part in steel, thermally molded part in ABS, injected foam, aluminum extruded handle, . . ., with their estimated mass. The result of the calculation for the manufacturing phase is 8.7767 points (column C_FabAss, line Door, Table 2), but designers or environmental experts can also obtain more detailed results and all the different impact categories if needed by simply requesting this. At this stage of the design process, it is obvious that the interpretation of the numerical data is not relevant because of the
lack of knowledge concerning the final product: it is a raw approximation. Nevertheless, the contributions of each brick to the total environmental impact of the product are generally very relevant, and the comparison of the different lifecycle alternatives is of great interest. 3.2. Product lifecycle optimization and product design The designers can use the brick information during the conceptual design phase, when they have only decided on the main functional elements of the product. At this stage, they already have many alternatives: - to minimize the environmental impact of a function (i.e. by changing the technology) or to minimize the environmental impact of a component (i.e. by changing its material). - to reorganize the structure of the product depending on the components to be actually reused at their end-of-usage cycles. So, designers can use outcomes from the bricks as soon as they have established the functional model and the main components of the product, but also at any time when they want to finalize the component choices and the structure of the product. One suggestion to do this (not described in this paper) is to use a functional model of the product to support the results produced by the bricks and by the lifecycle simulator. For our case study, the different analyses carried out on the functional model of the fridge led designers to focus firstly on the fridge body and to propose improvements. This focus decision was also supported by the ease of control of the manufacturing process of this component. The body is composed of five parts (see Table 2): lighting, casing, internal box, door, thermostat. The casing and the door were particularly redesigned during the project. 3.2.1. The casing For the casing, designers decided to reuse the foam (while changing the material) and the support tracks at the end of each usage cycle. Concerning the external surface, 90% is remanufactured and 10% recycled. The environmental impact of the remanufacturing process is estimated at around 40% of the EI of the manufacturing process of this component. That means: C EoLðRemÞ ¼ 10% C EoLðRecÞ þ 90% 0:4 C FabAss Table 3 shows the environmental impact values calculated for the casing. The first table is for the reference scenario and the second for a scenario with three usage cycles (two remanufacturing stages). They show the environmental impact for each usage cycle. The cumulative values of each usage cycle are then divided
Table 2 Normalized and weighted environmental impacts for the bricks built when designing the fridge (at t time of the design process and for the reference scenario). Weighted value Lighting Casing Internal box Door Thermostat Compressor Condenser Regulator Evaporator Gas Packaging Storage boxes Product Total %
C_Mat 0.0605 2.0876 0.6626 0.9600 0.0093 0.3313 0.0204 3.012 0.4468 0.0000 0.1816 0.3708
C_FabAss 4.3337 1.9425 0.1486 8.7767 0.0032 0.1772 0.0081 0.0068 0.0435 0.0000 0.0000 0.1025
C_Dis
P_Ass
16.144 38%
P_Use
P_Rec
0.000 0%
C_EoL_Rec 0.0296 1.9448 0.5204 0.8843 0.0088 0.3848 0.0237 0.0148 0.7115 0.0000 0.0158 0.4191
0.0000 5.144 12%
P_Dis
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
0.000 0%
0.2195 0.220 1%
25.9244 25.924 61%
25.9244 0.000 0%
4.957 12%
Total
%
4.965 2.035 0.292 8.852 0.004 0.124 0.005 0.005 0.221 0.000 0.166 0.054 26.144
12% 5% 1% 21% 0% 0% 0% 0% 1% 0% 0% 0% 62%
42.474
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Table 3 Comparative tables for the environmental impact of the casing: reference scenario and the scenario with three usage phases.
Table 4 Comparative tables for the environmental impact of the door: reference scenario and scenario with three usage cycles.
Table 5 Normalized and weighted environmental impacts for the bricks in the case of the final scenario. Weighted value Lighting Casing_Ext_Surf Casing_Comp_Bodyy Casing_Foam Casing_Tracks Internal box Door_Body Door_Steel_Handle Door_Ubcap Thermostat Compressor Condenser Regulator Evaporator Gas Packaging Storage boxes Product Total %
C_Mat 0.0605 0.6667 0.1307 0.0870 0 0309 0.6626 0.1424 0.0056 0.0131 0.0093 0.3313 0.0204 0.0127 0.4468 0.0000 0.1816 0.3708
C_FabAss 4.9337 0.6230 0.0227 0.0073 0.0007 0.1496 0.3016 0.0016 0.0037 0.0032 0.1772 0.0081 0.0068 0.0435 0.0000 0.0000 0.0000
C_Dis
P_Ass
6.390 15%
P_Use
P_Rec
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0 0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
3.172 7%
P_Dis
0.000 0%
0.000 0%
0.2195 0.220 1%
25.9244 25.924 61%
C_EoL_Rec
TOTAL
%
0.0296 0.0493 0.0739 0.0526 0.0197 0.5204 0.1271 0.0011 0.0079 0.0088 0.3848 0.0237 0.0148 0.7115 0.0000 0.0158 0.4191
4.965 1.245 0.074 6.644 0.012 0.292 0.317 0.006 0.009 0.004 0.124 0.005 0.005 0.221 0.000 0.166 0.054 26.144
14% 4% 0% 0% 0% 1% 1% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 75%
0.0000 0.000 0%
2.465 6%
33.242
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by the number of usage cycles to obtain a comparable environmental impact value. This value is necessary to give a real indicator to the designers and to be able to estimate the EI savings. 3.2.2. The door For the door, the aluminum handle was replaced by a steel handle (remanufactured two times) and a plastic hubcap (recycled). Table 4 shows the results for the reference scenario and for the new proposal with two remanufacturing phases (three usage cycles). In this case, EI savings (8.521 points) mainly come from the new material of the handle. 3.2.3. Results for the whole product lifecycle Table 5 shows the results for the environmental impact of the refrigerator modified as previously explained for the casing and the door. The modifications permitted a saving of 9.232 points (42.474 points against 33.242 points). The impact for the manufacturing and assembly phase of the components has been decreased by 3, and by 2 for the material extraction phase. 4. Conclusion In this paper, a method to support designers in developing the product lifecycle scenario most suitable from an environmental point of view has been presented. The tool that supports the method is based on LCA and can be used during the conceptual design phase. It is based on the concept of lifecycle bricks created to help designers iteratively build the product lifecycle and analyze LCA results. It is a means of observing the potential rapid environmental improvements and of clearly identifying the necessary design improvements. The product structure does not need to be accurately defined to begin this evaluation. This can be carried out with just a few abstracted data very early on and can be refined throughout the design process. The main objective is to make designers confident about environmental impact when selecting solutions. They are immediately aware of the environmental contribution of the lifecycle of the component they are describing, and so are assisted in controlling their impact For products with many components and with many end-of-life strategies, it becomes very difficult to manually calculate the final impact in a limited time, which could limit the number of lifecycle alternatives tested by designers. So, a software is currently under construction [5] to improve the integration of these results into the product functional model during the conceptual design phase. References [1] Nielsen, P.H., Wenzel, H., 2002, Integration of Environmental Aspects in Product Development: a Stepwise Procedure Based on Quantitative Life Cycle Assessment, Journal of Cleaner Production, 10:247–257.
[2] Finkbeiner, M., Hoffmann, R., Ruhland, K., Liebhart, D., Stark, B., 2006, Application of Life Cycle Assessment for the Environmental Certificate of the Mercedes-Benz S-Class, Journal of Life Cycle Assessment, 11:240–246. [3] Wentzel, H., Hauschild, M., Alting, L., 2001, Environmental Assessment of Products—vol. 1: Methodology Tools and Case Studies in Product Development, Kluwer Academic Publishers, Norwel, Mass., USA. [4] Jacobsson, N., 2000, Emerging Product Strategies, Selling Services of Remanufactured Product, Licenciate Dissertation, Lund University. [5] Gehin, A., Zwolinski, P., Brissaud, D., 2008, A Tool to Implement Sustainable End-of-Life Strategies in the Product Development Phase, Journal of Cleaner Production, 16/5:566–576. [6] Ginutini, R., Gaudette, K., 2003, Remanufacturing: The Next Great Opportunity for Boosting US Productivity, Business Horizons, 41–48. [7] Kerr, W., Ryan, C., 2001, Eco-Efficiency Gains from Remanufacturing—A Case Study of Phocopier Remanufacturing at Fuji Xerox Australia, Journal of Cleaner Production, 9:75–81. [8] Rose, C., 2000, Design for Environment: A Method for Formulating Product End-of-Life Strategies, PhD Thesis, Stanford University. [9] Zwolinski, P., Brissaud, D., 2008, Remanufacturing Strategies to Support Product Design and Redesign, Journal of Engineering Design, 19/4:321–335. [10] Lopez, M., Zwolinski, P., Brissaud, D., 2006, Integrated Design of Remanufacturable Products Based on Product Profiles, Journal of Cleaner Production, 14– 16:1333–1345. [11] Zwolinski, P., Brissaud, D., Llerena, D., Millet, D., 2007, Sustainable Products? Necessity for an Overall Design Approach. International Journal of Environmentally Conscious Design and Manufacturing, 13/3/4:1–14. [12] Zwolinski, P., Lopez-Ontiveros, M.A., Brissaud, D., 2004, Product End of Life Characterisation for Integrated Design, International Journal of Production Engineering and Computers, 6/7:85–89. [13] Haoues, N., Zwolinski, P., Cornier, A., Brissaud, D., 2004, How to Integrate End of Life Disassembly Constraints in the Early Design Phases? International Journal of Production Engineering and Computers, 6/7:59–64. [14] Park, J., Seo, K., 2006, A Knowledge-Based Approximate Life Cycle Assessment System for Evaluating Environmental Impacts of Product Design Alternatives in a Collaborative Design Environment, Advanced Engineering Informatics, 20:147–154. [15] Caspersen, N., Sørensen, A., 1998, Improvements of Products by Means of Lifecycle Assessment: High Pressure Cleaners, Journal of Cleaner Production, 6:371–380. [16] Choi, B.-C., Shin, H.-S., Lee, S.-Y., Hur, T., 2006, Life Cycle Assessment of a Personal Computer and its Effective Recycling Rate, Journal of Life Cycle Assessment, 11:122–128. [17] Coppens, C., Millet, D., Le Coq, M., 2002, Design for Recycling Methodology: Evaluating and Improving the Recovery Aptitude of an Automotive Function, International Journal of Vehicle Design, 29/4:307–316. [18] Tonnelier, P., Millet, D., Richir, S., Lecoq, M., 2005, Is it Possible to Evaluate the Recovery Potential Earlier in the Design Process? Proposal of a Qualitative Evaluation Tool. Journal of Engineering Design, 16/3:297–309. [19] Millet, D., Bistagnino, L., Lanzavecchia, C., Camous, R., Poldma, T., 2007, Does the Potential of the Use of LCA Match the Design Team Needs? Journal of Cleaner Production, 15/4:335–346. [20] Kaebernick, H., Sun, M., Kara, A., 2003, Simplified Life Cycle assessment for the Early Design Stages of Industrial Products, Annals of the CIRP, 52/1:25–28. [21] Brissaud, D., Zwolinski, P., 2004, End-of-Life-Based Negotiation Throughout the Design Process, Annals of the CIRP, 53/1:155–158. [22] Zwolinski, P., Brissaud, D., 2005, Designing Products that are Never Discarded, In: Brissaud, D., Tichkiewitch, S., Zwolinski, P. (Eds.), Innovation in Life Cycle Engineering and Sustainable Development, Springer Berlin, Germany, vol.:2006, pp 225–244. [23] Prudhomme, G., Zwolinski, P., Brissaud, D., 2003, Integrating into the Design Process the Needs of those Involved in the Product Life Cycle, Journal of Engineering Design, 14/3:333–353. [24] Zwolinski, P., Prudhomme, G., Brissaud, D., 2003, Environment and Design: Towards Methods and Tools for Integration and Co-operation, in Tichkiewitch S, Brissaud D, (Eds.) Methods and Tools for Cooperative and Integrated Design.. Kluwer Academic Publishers, Norwel, Mass., USA, pp. 223–232.
Contents lists available at ScienceDirect
CIRP Journal of Manufacturing Science and Technology journal homepage: www.elsevier.com/locate/cirpj
Integrated design of product lifecycles—The fridge case study Alexis Gehin, Peggy Zwolinski *, Daniel Brissaud G-SCOP Laboratory, Grenoble University, 46 avenue Fe´lix Viallet, 38031 Grenoble Cedex 1, France
A R T I C L E I N F O
A B S T R A C T
Article history: Available online 21 June 2009
To help engineering designers understand and translate environmental constraints into effective actions, new methods and tools for engineering have to be developed and used at the product conceptual design phase. Indeed, this design stage is mainly concerned with the actual trade-off among all the constraints, therefore generating more environmentally benign design alternatives. This paper aims at presenting a method to support designers in the definition of the product lifecycle scenario, including component lifecycle scenarios, when designing the elements of the structure of the product. The current design can be continuously assessed by lifecycle analysis (LCA) methods. The main concept used is the lifecycle brick that has been proposed to support both the product model and the lifecycle scenario. The data encapsulated in the model are computed to outcome quantitative contribution to the environment in now classical eco-points. The method is illustrated via a fridge case study. ß 2009 CIRP.
Keywords: Engineering design Lifecycle scenario Environmental impacts Simplified LCA
1. Introduction The future of the next generations lies in our efficiency in reducing the environmental degradation of our planet. The challenge of sustainable development encompasses different actions, among which the reduction of polluting emissions and production of wastes are of primary importance. Engineering and manufacturing are being challenged to create the ‘‘new world.’’ Recent directives in Europe hold the manufacturers responsible for their products even after they are sold, applying the Extended Producer Responsibility principle. Facing the dilemma of being competitive and clean at the same time, industrialists are willing or are forced to take actions to reduce the environmental burden of their activity [1]. The hypothesis is that designing products with an environmental sense of responsibility as soon as possible can make it possible to anticipate more and more demanding regulations [2]. This paper focuses on the product and on its ability to be clean and re-valuable. In order to help engineering designers understand and translate the environmental constraints into effective actions, a methodology that enables the generation of more environmentally benign design alternatives according to LCA criteria [3] has been developed. It is assumed that the focus of designers should be (1) on the entire lifecycle of the product and consequently that they must know more about each phase and (2) on the end-of-life strategies where many gains could be made by reusing components with intelligence. This paper aims at presenting a part of this work using simplified lifecycle
* Corresponding author. Tel.: +33 4 76 82 52 74; fax: +33 4 76 82 70 43. E-mail address: [email protected] (P. Zwolinski). 1755-5817/$ – see front matter ß 2009 CIRP. doi:10.1016/j.cirpj.2009.05.002
impact assessment (LCIA) to assess the environmental impacts (EIs), and emphasizes the concept of lifecycle bricks to structure the product data when designing. This concept supports the development of the adequate product lifecycle model for environmental assessment during the early design phase. This central proposition (Section 2) enables the designer to rapidly formulate lifecycle scenarios and then test them according to LCIA methods. Results can be visualized quantitatively and graphically as well as connected to the elements of the product model. The methodology proposed in the paper is illustrated via the design of a fridge (Section 3). 2. Method for the product Lifecycle environmental assessment during the conceptual design phase The perception of sustainable products has changed over the past few years, sliding from a cradle-to-grave approach to a cradleto-cradle one [4,5]. Closed-loop industrial systems imply that OEM do not only take care of product manufacturing and use, but also of how products can be taken back and treated at their end-of-life or re-included in new lifecycles [6,7]. Therefore, the role of designing the products whose components might be reused, remanufactured or recycled is of major importance [8,9]. To keep and reuse the high manufacturing added-value embedded in each element of a product when it is discarded, the EoL strategy of the whole product depends on the most appropriate EoL scenario of each product element. Consequently, the product EoL strategy should be a mix of the three EoL scenarios: reuse, remanufacture, and recycle, and is named 3R strategy in the paper. Unfortunately, existing engineering design methodologies do not take into account the fact that products might go through several usage cycles, yet this
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aspect will condition the design of the product [10] as well as its environmental performance [11]. It has also been said for many years that the available design methodologies cannot efficiently support the environmental perspective while still being in the conceptual design phase [12]. Indeed - Guidelines have been developed to guide designers’ decisions in the early design phases. These guidelines are well adapted to the conceptual design phase, used as drivers for a sustainable design, but have failed to return usable quantitative indicators that could be analysed and balanced with the other design indicators at this stage of the design project [13]. - Lifecycle analysis (LCA) to evaluate the environmental impacts of the product [14–16] and design for environment (DfE) tools [17,18] are frequently used late, during the detailed design phase, only when a large set of data are available (components, weights, material, joining techniques, manufacturing processes, . . .) but also when modifications to the product are difficult to realize without a large waste of time and money [19,20]. Our general vision on design methodology is to run a situationbased approach [21] that focuses on the negotiation of strategies and their impacts on product characteristics throughout the product development phase. It is assumed that negotiations between product engineers and end-of-life strategy engineers can be prepared, performed, and then controlled. For that reason, an innovative way of modeling products during the early design stage has been proposed. First of all, it allows taking into account 3R strategies and consequently the product lifecycle over several usage cycles. Second, this model makes it possible to create product lifecycle scenarios suitable for quantitative environmental assessment. Third, it has been adapted to be used by practitioners. The proposed methodology is based on The ‘‘lifecycle bricks’’ to support designers in building lifecycle scenarios. A method to assess sustainable lifecycles from an environmental perspective. 2.1. The lifecycle bricks to support designers in building lifecycle scenarios As described in the introduction, there are large strategies that allow retention of the added value of product components after
215
their usage cycle, such as recycle, remanufacture, and reuse [22]. While developing the product, designers need to quickly determine the lifecycle strategy applied to each component, and therefore require some robust indicators to select the most appropriate [23]. From an environmental point of view, it is thus necessary to consider not only the initial use phase of the product, but as many phases as the product can have. The lifecycle of the product is said to be closed (closed-loop) though, and the product will ‘‘live’’ through as many loops as possible before being finally removed from the manufacturing world. In order to do that, a representation of the product lifecycle is needed. The product lifecycle is classically represented as a sequence of phases, namely (and to make it simple) material extraction, manufacturing and assembly, use and end-of-life that make sense for environmentalists. Frequently, the LCA experts realize the analysis from the product bill of materials. They list the components of similar materials and calculate the sum of the mass for each material present in the product. Then, they carry out the analyses on these aggregated values without being able to know thereafter the exact contribution of each component. To avoid these aggregated results that are not usable by designers to improve the components and products design, the classical lifecycle representation has been adapted (see Fig. 1): - More lifecycle phases have been defined, depending on the designers’ expertise in being able to consider the real causes of the environmental impacts. So, eight generic phases have been used to model the lifecycle from a designer’s point of view: (1) material extraction and transformation, (2) component manufacturing and assembly, (3) component distribution, (4) product assembly, (5) product distribution, (6) product use, (7) product take-back, (8) component end-of-life. - Two different levels have been highlighted: the product level and the component level. Indeed, recovery strategies belong to the component lifecycles. Thus, when developing the product, designers have to determine an EoL scenario for each component, as components do not all have the same ability to be recovered at their end-of-life. The different flux of components and products are represented by arrows in Fig. 1. The possible ways or strategies are not exclusive and have to be precisely defined for each component. It is quite frequently the case that a part of a component in end-of-life can be remanufactured whereas the other parts of the component are recycled.
Fig. 1. The Lifecycle representation.
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The model proposed is based on the lifecycle brick concept. The objective is to help designers to rapidly build lifecycle scenarios that can be environmentally assessed, so that new design alternatives can be generated and then tested. A lifecycle scenario is composed of a sequence of lifecycle phases represented by lifecycle bricks for the products or for the component. The lifecycle bricks were built with the aim of delivering relevant results to designers who are not environmental experts: this is directly linked to the engineering design feature of the product and its lifecycle. The bricks give information to enable evaluation of the environmental impact of the product components for each lifecycle phase of the product. The objective is to allow designers to have access to sufficient detailed information that can be usable in analyzing their design choices of materials, manufacturing processes, logistics, usage, end-of-life, . . . So, a lifecycle brick has two dimensions: a lifecycle phase and a product/component dimension. It addresses Components for the phases while the product is disassembled (number 1, 2, 3, and 8 on Fig. 1). The whole product for the phases while the product is assembled (number 4, 5, 6, and 7 on Fig. 1). The lifecycle brick is defined as a black box containing the necessary data for the calculation of environmental impacts according to the lifecycle impact assessment methodology. Each brick contains the following information (see Fig. 2): An identifier, based on the name of the lifecycle phase and the component or product name. Data related to the components or product and relevant to the lifecycle phase: mass, type of material used. The processes related to the lifecycle phase, and for each of them the consumption and impact towards the environment. The results of the environmental impact assessment after they have been evaluated. They are stored as impacts by categories, normalized impacts, and weighted impacts. As illustrated in Fig. 2, the lifecycle brick is a means of linking product design data to expected lifecycle strategies while giving an environmental score that depends on these two aspects. While the product is being designed, four product-level bricks are compulsorily created, and four component-level bricks for each new component are created. Designers are asked to provide the data related to each brick: the more precise the information, the more detailed the lifecycle models. When designers need to make a design choice, or whenever a brick is modified, the environmental assessment is made and the environmental criterion is added to the decision process. Thus, designers can work on design alternatives at both the component and product levels, while having access to quantitative indicators related to the environment, and taking into account the overall lifecycle of the products.
2.2. The environmental assessment of sustainable lifecycles The main objective in defining the design methodology within the framework of sustainable development was that designers could take actions on component end-of-life strategies [12]. Indeed, this would certainly make them act on other lifecycle phases [24]. During the design process they develop many lifecycle options and thus need to determine the best one, or at least not the worst one, for the environment. So, the proposition is to assess lifecycles for a specific design. Designers can use the lifecycle bricks to build lifecycles, and a method has been developed that makes it possible to model closedloop systems using the brick concept. So, the bricks being defined let us explain the rules for building lifecycles of closed-loop systems (Fig. 3): A lifecycle is created as soon as the first component is created. The four product-level bricks are built as well as the four component-level bricks. The environmental impact of the product is the sum of the impacts of the bricks (only for weighted impacts or normalized impacts for certain methods). Each time the designer creates a new component, four new bricks of the component level are created and new impacts are added to the former ones for each lifecycle phase and for the whole product. For closed-loop strategies (3R strategies), designers have to evaluate ‘‘u’’ the number of usage cycles that the component can support at its maximum, and the component end-of-pipe strategy to take place at the end. Because the strategy cannot certainly be 100% efficient due to the recovering process capability (quality of take-back parts, percentage of products recovered, efficiency of the remanufacturing process, . . .), endof-pipe scenarios have to be determined as well as the estimation of the percentage of components that will be effectively reused/ remanufactured. Once the model is ready for calculation, the environmental impacts are determined. Then, the impacts are brought back to one single usage cycle so that the designers can compare the different lifecycles alternatives they have envisioned. The variables and rules developed in order to build the lifecycle model of closed-loop systems are described as follows: Notations: i is used to identify the component (1 to n components). ui is the number of usage cycles (loops) that the components i can support at maximum. xi is the percentage of components that can be effectively reused, remanufactured, or recycled in the loop, at the end of the usage phase. In a first approach, it is assumed to be the same at every loop (same end-of-life option and same percentage). j is used to identify the lifecycle phase: 8 j = 1 for the material extraction and transformation phase. 8 j = 2 for the components manufacturing and assembly phase. 8 j = 3 for the components distribution. 8 j = 4 for the components end-of-life phase.
Fig. 2. Description of the data stored in a lifecycle brick.
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217
Fig. 3. Product lifecycle construction.
Bi,j represents the environmental impact of the component i for the lifecycle phase j (environmental impact of the brick (i,j)). EoUi represents the end-of-usage option for the component i (reused, remanufactured, recycled). EoLi represents the end-of-life option for the component i (recycled, incinerated, landfilled) and for the percentage of components that cannot be reused at the end of the usage cycle. IEmati, IEmani, IEdisi, IEEoLi, represent the values of a component environmental impact, per unit of usage (the corresponding impacts of each loop are added and the result is then divided by the number of loops). IEmat, IEman, IEdis, IEEoL, represent the environmental impact of the product for each lifecycle phase, per unit of usage. Rules: (1) If the component i is recycled in a closed-loop system (it is assumed that the recycled material is used to manufacture the same type of components) or remanufactured, or reused, then for each usage cycle between 2 and ui and for the percentage of recovered product, the material stage impact is set to zero. So, the value of the material phase environmental impact, per unit of usage, for the component i, is IEmati ¼ Bi;1
f1 þ ðui 1Þð1 xi =100Þg ui
(2) If the component i is remanufactured, or reused, then for each usage cycle between 2 and ui and for the percentage of recovered product, the manufacturing impact is set to zero. In this case, the value of the manufacturing phase environmental impact, per unit of usage, for the component i, is if EoUi ¼ freused or remanufacturedg IEfabi ¼ Bi;2
f1 þ ðui 1Þð1 xi =100Þg ui
If the component i is recycled in the closed-loop system, the value of the manufacturing phase environmental impact, per unit of usage, for the component i, is if EoUi ¼ frecycledg
IEfabi ¼ Bi;2
(3) It is assumed that the distribution impact is the same whatever the chosen strategy for the component. So, the value of the distribution phase environmental impact, per unit of usage, for the component i, is IEdisi ¼ Bi;3 (4) If the component i is remanufactured, or reused, the environmental cost of these processes are included in the end-of-life environmental impact. So, the value of the
end-of-life phase environmental impact, per unit of usage, for the component i, is ½fðui 1Þ ðBi;4 ÞEoU xi =100g i
IEEoLi ¼
þf1 þ ðui 1Þð1 xi =100Þ ðBi;4 ÞEoL g i
ui
ðBi;4 ÞEoU returns the environmental impact corresponding i to the reuse case or to the remanufacturing case or to the recycling case. ðBi;4 ÞEoL returns the EoL environmental impact correspondi ing to the recycling case or to the incineration case or to the landfill case. (5) The environmental value of a component per unit of usage is calculated by summing up the environmental impact of each brick of a componentIEi ¼ IEmati þ IEmani þ IEdisi þ IEEoLi (6) The environmental value of a lifecycle phase per unit of usage for the product is calculated by summing up the environmental impact of each brick for the corresponding lifecycle phase. X IEmati IEmat ¼ ð1 ! nÞ X IEman ¼ IEmani ð1 ! nÞ X IEdis ¼ IEdisi ð1 ! nÞ X IEEoL ¼ IEEoLi ð1 ! nÞ This tool makes it possible to build a product lifecycle very promptly, even with rough data, which the designers upgrade step by step. As soon as they need an evaluation of the environmental performance, they can launch the calculation and compare two design alternatives. The following section describes a case study of a fridge design process. 3. Case study: the Use of the 3R method during the design process of a fridge 3.1. The product description and the first environmental evaluation The product chosen for illustrating the methodology is a classical refrigerator with a 200 l storage capacity for the cooling volume and 80 l for the freezer. The energy consumed per year is limited to 200 kWh and is a mix of French energy. This refrigerator satisfies the needs of three to five persons for a lifetime of 10 years. Depending on the numerous legislative constraints, the overall optimization of this product from an environmental point of view is necessary. At the beginning of the conceptual design phase, four main components (a main component is a functional feature that will finally be implemented in several parts and physical components) have been identified: the body, the cooling system, the storage boxes, and the packaging.
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218 Table 1 Component data (extract). Component
Part
Material (gr)
Process
Door
Body Accessories Foam Handle
Steel (4000) ABS (1800) Foam (1500) Al (250)
Stamping Thermoforming Injection Extrusion
Casing
Ext surface Compressor body Foam Tracks
Steel (500) ABS Foam (4700) Steel (1000)
Stamping Thermoforming Injection Rolling
Lighting
...
During the project, designers went about proposing solutions. They proposed different parts and components for implementing each main component, and established the data necessary to construct the lifecycle bricks. For each component, as for the door, the casing . . . it is necessary to precisely determine the material, along with the estimated weight and the possible manufacturing process (Table 1). In our study, the data is derived mainly from an existing EDIP case study [3]. The reference lifecycle is when all the components are recycled at their end-of-life after one usage cycle. The environmental impact for this reference lifecycle will be compared with the values obtained for the other lifecycle propositions as evidence of their environmental efficiency. Table 2 shows the environmental impact (in eco-points) of the fridge partially described in Table 1. Horizontally are the main components of the product; their scores are related to their design at the moment the calculation was generated. Vertically are the lifecycle phases attached to either the sub-assembly (C for component) or the product itself (P): material extraction (Mat, only for C), manufacturing (FabAss, only for C), distribution/logistics (Dis, for C and for P), assembly (Ass, only for P), use (use, only for P), recovery (Rec, for P and for C) including the end-of-usage lifecycle of each component; in this study all components are recycled at their end of life (EoL_Rec, only for C). In the example of the door (Table 1), the necessary data contained in the brick enables calculation of the score for the normalized and weighted environmental impacts: stamped part in steel, thermally molded part in ABS, injected foam, aluminum extruded handle, . . ., with their estimated mass. The result of the calculation for the manufacturing phase is 8.7767 points (column C_FabAss, line Door, Table 2), but designers or environmental experts can also obtain more detailed results and all the different impact categories if needed by simply requesting this. At this stage of the design process, it is obvious that the interpretation of the numerical data is not relevant because of the
lack of knowledge concerning the final product: it is a raw approximation. Nevertheless, the contributions of each brick to the total environmental impact of the product are generally very relevant, and the comparison of the different lifecycle alternatives is of great interest. 3.2. Product lifecycle optimization and product design The designers can use the brick information during the conceptual design phase, when they have only decided on the main functional elements of the product. At this stage, they already have many alternatives: - to minimize the environmental impact of a function (i.e. by changing the technology) or to minimize the environmental impact of a component (i.e. by changing its material). - to reorganize the structure of the product depending on the components to be actually reused at their end-of-usage cycles. So, designers can use outcomes from the bricks as soon as they have established the functional model and the main components of the product, but also at any time when they want to finalize the component choices and the structure of the product. One suggestion to do this (not described in this paper) is to use a functional model of the product to support the results produced by the bricks and by the lifecycle simulator. For our case study, the different analyses carried out on the functional model of the fridge led designers to focus firstly on the fridge body and to propose improvements. This focus decision was also supported by the ease of control of the manufacturing process of this component. The body is composed of five parts (see Table 2): lighting, casing, internal box, door, thermostat. The casing and the door were particularly redesigned during the project. 3.2.1. The casing For the casing, designers decided to reuse the foam (while changing the material) and the support tracks at the end of each usage cycle. Concerning the external surface, 90% is remanufactured and 10% recycled. The environmental impact of the remanufacturing process is estimated at around 40% of the EI of the manufacturing process of this component. That means: C EoLðRemÞ ¼ 10% C EoLðRecÞ þ 90% 0:4 C FabAss Table 3 shows the environmental impact values calculated for the casing. The first table is for the reference scenario and the second for a scenario with three usage cycles (two remanufacturing stages). They show the environmental impact for each usage cycle. The cumulative values of each usage cycle are then divided
Table 2 Normalized and weighted environmental impacts for the bricks built when designing the fridge (at t time of the design process and for the reference scenario). Weighted value Lighting Casing Internal box Door Thermostat Compressor Condenser Regulator Evaporator Gas Packaging Storage boxes Product Total %
C_Mat 0.0605 2.0876 0.6626 0.9600 0.0093 0.3313 0.0204 3.012 0.4468 0.0000 0.1816 0.3708
C_FabAss 4.3337 1.9425 0.1486 8.7767 0.0032 0.1772 0.0081 0.0068 0.0435 0.0000 0.0000 0.1025
C_Dis
P_Ass
16.144 38%
P_Use
P_Rec
0.000 0%
C_EoL_Rec 0.0296 1.9448 0.5204 0.8843 0.0088 0.3848 0.0237 0.0148 0.7115 0.0000 0.0158 0.4191
0.0000 5.144 12%
P_Dis
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
0.000 0%
0.2195 0.220 1%
25.9244 25.924 61%
25.9244 0.000 0%
4.957 12%
Total
%
4.965 2.035 0.292 8.852 0.004 0.124 0.005 0.005 0.221 0.000 0.166 0.054 26.144
12% 5% 1% 21% 0% 0% 0% 0% 1% 0% 0% 0% 62%
42.474
A. Gehin et al. / CIRP Journal of Manufacturing Science and Technology 1 (2009) 214–220
219
Table 3 Comparative tables for the environmental impact of the casing: reference scenario and the scenario with three usage phases.
Table 4 Comparative tables for the environmental impact of the door: reference scenario and scenario with three usage cycles.
Table 5 Normalized and weighted environmental impacts for the bricks in the case of the final scenario. Weighted value Lighting Casing_Ext_Surf Casing_Comp_Bodyy Casing_Foam Casing_Tracks Internal box Door_Body Door_Steel_Handle Door_Ubcap Thermostat Compressor Condenser Regulator Evaporator Gas Packaging Storage boxes Product Total %
C_Mat 0.0605 0.6667 0.1307 0.0870 0 0309 0.6626 0.1424 0.0056 0.0131 0.0093 0.3313 0.0204 0.0127 0.4468 0.0000 0.1816 0.3708
C_FabAss 4.9337 0.6230 0.0227 0.0073 0.0007 0.1496 0.3016 0.0016 0.0037 0.0032 0.1772 0.0081 0.0068 0.0435 0.0000 0.0000 0.0000
C_Dis
P_Ass
6.390 15%
P_Use
P_Rec
0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0 0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
3.172 7%
P_Dis
0.000 0%
0.000 0%
0.2195 0.220 1%
25.9244 25.924 61%
C_EoL_Rec
TOTAL
%
0.0296 0.0493 0.0739 0.0526 0.0197 0.5204 0.1271 0.0011 0.0079 0.0088 0.3848 0.0237 0.0148 0.7115 0.0000 0.0158 0.4191
4.965 1.245 0.074 6.644 0.012 0.292 0.317 0.006 0.009 0.004 0.124 0.005 0.005 0.221 0.000 0.166 0.054 26.144
14% 4% 0% 0% 0% 1% 1% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 75%
0.0000 0.000 0%
2.465 6%
33.242
220
A. Gehin et al. / CIRP Journal of Manufacturing Science and Technology 1 (2009) 214–220
by the number of usage cycles to obtain a comparable environmental impact value. This value is necessary to give a real indicator to the designers and to be able to estimate the EI savings. 3.2.2. The door For the door, the aluminum handle was replaced by a steel handle (remanufactured two times) and a plastic hubcap (recycled). Table 4 shows the results for the reference scenario and for the new proposal with two remanufacturing phases (three usage cycles). In this case, EI savings (8.521 points) mainly come from the new material of the handle. 3.2.3. Results for the whole product lifecycle Table 5 shows the results for the environmental impact of the refrigerator modified as previously explained for the casing and the door. The modifications permitted a saving of 9.232 points (42.474 points against 33.242 points). The impact for the manufacturing and assembly phase of the components has been decreased by 3, and by 2 for the material extraction phase. 4. Conclusion In this paper, a method to support designers in developing the product lifecycle scenario most suitable from an environmental point of view has been presented. The tool that supports the method is based on LCA and can be used during the conceptual design phase. It is based on the concept of lifecycle bricks created to help designers iteratively build the product lifecycle and analyze LCA results. It is a means of observing the potential rapid environmental improvements and of clearly identifying the necessary design improvements. The product structure does not need to be accurately defined to begin this evaluation. This can be carried out with just a few abstracted data very early on and can be refined throughout the design process. The main objective is to make designers confident about environmental impact when selecting solutions. They are immediately aware of the environmental contribution of the lifecycle of the component they are describing, and so are assisted in controlling their impact For products with many components and with many end-of-life strategies, it becomes very difficult to manually calculate the final impact in a limited time, which could limit the number of lifecycle alternatives tested by designers. So, a software is currently under construction [5] to improve the integration of these results into the product functional model during the conceptual design phase. References [1] Nielsen, P.H., Wenzel, H., 2002, Integration of Environmental Aspects in Product Development: a Stepwise Procedure Based on Quantitative Life Cycle Assessment, Journal of Cleaner Production, 10:247–257.
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