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Journal of Cleaner Production 78 (2014) 174e183

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Journal of Cleaner Production

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Comparing Biomimicry and Cradle to Cradle with Ecodesign:a case study of student design projects

Ingrid C. de Pauw*, Elvin Karana 1, Prabhu Kandachar 2, Flora PoppelaarsLandbergstraat 15, 2628CE Delft, the Netherlands

a r t i c l e i n f o

Article history:Received 11 October 2013Received in revised form26 March 2014Accepted 28 April 2014Available online 9 May 2014

Keywords:Nature-inspired designDesign strategiesSustainable product designContext-specific solutions

* Corresponding author. Tel.: þ31 15 2788667; fax:E-mail addresses: i.c.depauw@tudelft.nl (I.C. de

(E. Karana), p.v.kandachar@tudelft.nl (P. Kandachtudelft.nl (F. Poppelaars).

1 Tel.: þ31 15 2785726; fax: þ31 15 2781839.2 Tel.: þ31 15 2785769; fax: þ31 15 2781839.3 Cradle to Cradle� and C2C� are registered trad

nationale Umweltforschung GmbH (EPEA) and McChemistry, LLC.

http://dx.doi.org/10.1016/j.jclepro.2014.04.0770959-6526/� 2014 Elsevier Ltd. All rights reserved.

a b s t r a c t

In the field of sustainable product development, a new type of design strategies is being implemented,based on ‘learning from nature’. Biomimicry and Cradle to Cradle, two Nature-Inspired Design Strategies,provide principles and tools specifically aimed at design practice. However, research into their applica-tion and how they influence the outcome of the design process is scarce. Consequently, there is a lack ofknowledge as to how these design strategies differ from, and may add to, a validated and well-established approach such as Ecodesign.

This paper describes and discusses an explorative case study, comparing how students designed a‘sustainable product’ by applying either Biomimicry, Cradle to Cradle, or Ecodesign. The outcomes of 27student groups across two years were analyzed through content analysis and statistical tests. Significantdifferences were found in the ‘design focus’ of the groups, depending on which design strategy theyapplied. Furthermore, groups that applied Biomimicry and Cradle to Cradle included functional alter-natives and user needs more often than Ecodesign groups. Addressing ‘context-specific opportunities’ inthe designers’ solution space was found to be a key difference between nature-inspired design andEcodesign. We argue that this focus on product context may have helped the students to integrate so-lutions at the level of functions and needs in their design process. All three strategies successfully guidedthe students in generating a design. However, only Ecodesign provided quantitative evaluation tools. Ourstudy confirms the need for such tools in the design process, to prevent unforeseen environmentalimpacts of the designs in the product life cycle.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Designers can apply different strategies for sustainable productdesign. Strategies provide the general plan of action for a projectand the tactics (i.e. methods and techniques) for reaching thedesign goal (Cross, 2000). Ecodesign is one of the most widelyrecognized and utilized strategies for including environmentalsustainability in the product design process. Biomimicry (Benyus,1997) and Cradle to Cradle3 (McDonough and Braungart, 2002)are two examples of a relatively new type of strategies currently

þ31 15 2781839.Pauw), e.karana@tudelft.nl

ar), f.a.poppelaars@student.

emarks held by EPEA Inter-Donough Braungart Design

adopted in design practice and education, that take inspirationfrom the natural world. These Nature-Inspired Design Strategies(NIDS) “base a significant proportion of their theory on learningfrom nature and regard nature as the paradigm for sustainability”(De Pauw et al., 2010). Their application has generated inspiringresults, offering designers an alternative perspective towardsintegrating environmental sustainability as compared to otherstrategies such as Ecodesign.

However, few studies have analyzed the application ofBiomimicry and Cradle to Cradle in sustainable product design(see Section 2 of this paper). Insight into how they are applied andinfluence the outcome of the design process is lacking. The casestudy presented in this paper aims at developing our understand-ing of NIDS, by exploring how Biomimicry and Cradle to Cradlehelped students in designing a ‘sustainable product’ as compared tostudents using Ecodesign. The findings are based on the resultsfrom two consecutive courses in which a total of 27 student groupsapplied one of the three strategies in a design assignment.

The study has threemain objectives, formulated on the basis of apre-study with 6 student groups (De Pauw et al., 2012): (1) to

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validate the application of the design strategies and analyzepossible differences in application between strategies; (2) toexplore whether the topics that the student groups focus on vary,depending on the strategy applied; and (3) to explore whethergroups that apply Biomimicry or Cradle to Cradle (NIDS) come upwith different types of solutions compared to groups that applyEcodesign (for example suggesting alternatives for fulfilling specificproduct functions, instead of implementing alternative materials inthe design).

The following section introduces the design strategies includedin this case study. Section 3 describes the research method and set-up of the study. The results are presented in three sections: theapplication of the strategies in Section 4, the differences in designfocus in Section 5, and the differences in the types of design solu-tions in Section 6. Section 7 discusses how the strategies may havehelped the students to develop their solutions, and Section 8 con-cludes how NIDS affected the outcomes as compared to Ecodesign.

2. Nature-Inspired Design Strategies and Ecodesign e a briefoverview

This section introduces the three design strategies included inthe study and describes key differences between both Nature-Inspired Design Strategies and Ecodesign. In line with the scopeof this research, this paper focuses on the application of the stra-tegies in the field of sustainable product design. Sustainableproduct design is understood as design aimed at generating prod-ucts that are beneficial to people, planet and profit.

2.1. Biomimicry

Biomimicry, as developed by Benyus, was first described in bookform in 1997 (Benyus, 1997). Various definitions are used inter-changeably in literature for Biomimicry, and related strategiesreferred by other scholars as Biomimetics, Bio-inspired design, andBionics (Vincent, 2009). However, when the emphasis is on findingsolutions that are (environmentally) sustainable, Biomimicry istypically the term used (Reap et al., 2005; Vincent, 2009). The coreconcept of Biomimicry is that nature has developed highly effective,sustainable ways of performing functions, which could benefitdesigners when tackling comparable challenges. In this paper,Biomimicry is defined accordingly as learning from nature fordeveloping sustainable solutions.

Benyus emphasizes that in order to achieve environmentallysustainable solutions, designers need to integrate biologicalknowledge at the level of forms, processes, and systems. To inte-grate ecosystem insights into design, so called ‘life’s principles’ ofbiology are provided. The aspirational goal of their application is tocreate “conditions conducive to life” (Benyus, 1997). According toits proponents, the Life’s Principles can be used to measure thesuccess of a design, and success requires the integration of (all)Life’s Principles (ibid). Biomimicry 3.8, an institute co-founded byBenyus, has developed different methods and tools for sustainableproduct design (published recently in Baumeister et al., 2013). Aselection of these methods and tools has been used in the casestudy presented in this paper (see Table 2 of Section 3).

Studies on the application of Biomimicry in sustainable productdesign are scarce. By analyzing three specific products, Reap et al.(2005) illustrate that ‘reductive’ Biomimicry, which mimics onlyforms and processes, does not necessarily render more sustainableoutcomes. Montana-Hoyos (2008), who combined Biomimicrywith several other strategies, acknowledges the need to include thesystems’ level of Biomimicry. Nevertheless, his findings do notprovide insight into the application of methods or tools forimplementing such ‘system lessons’. Volstad and Boks, in their

study on the usefulness of Biomimicry for (sustainable) productdesign, explicitly limit their study to the reductive form of Bio-mimicry and its use “as a source of inspiration and as a toolkit forsolving practical design problems” (Volstad and Boks, 2012). So far,research has focused on the more commonly used ‘biomimetic’elements of the strategy, as opposed to the Biomimicry tools andprinciples meant specifically for sustainable product design.

2.2. Cradle to Cradle

The core concept of Cradle to Cradle is to “take nature as amodelfor making things” and design products that, after their useful lives,become resources for new products (McDonough and Braungart,2002). This design strategy, as developed by Braungart andMcDonough, challenges designers to move beyond eco-efficiency,towards ‘eco-effectiveness’ (ibid).

Cradle to Cradle provides designers with three design principlesfor achieving eco-effectiveness, based on learning from naturalsystems: ‘waste equals food’, ‘use current solar income’, and ‘cele-brate diversity’ (McDonough et al., 2003). Apart from the principles,various design tools are available for Cradle to Cradle design,offered via courses by EPEA, an agency founded by Braungart, aswell as a number of Universities. The principles and tools includedin the case study are presented in Table 2 of Section 3. Next to thedesign tools, a certification program has been developed to allowcompanies to market their progress in applying Cradle to Cradle(C2C Products Innovation Institute, 2012). The certification criteriafocus on the implementation of the strategy within an organiza-tion, but not on assessing the ultimate result, i.e. ‘eco-effectiveness’of the design.

Several studies describe the theoretical and practical advantagesand disadvantages of Cradle to Cradle (for example Bjørn andHauschild, 2012; McDonough et al., 2003; Reijnders, 2008) but, aswith Biomimicry, studies analyzing the application of the strategyin product design are scarce. Both Rossi et al. (Rossi et al., 2006) andLee and Bony (2009) studied the design of the Mirra chair by officefurniture manufacturer HermaneMiller, describing the designteam’s achievements that focused on the ‘waste equals food’principle. Additionally, Bakker et al. (2009) studied the applicationof this design strategy based on graduation projects and literature.These studies shed light on the merits of and difficulties encoun-tered in design projects, but how Cradle to Cradle affects the out-comes remains to be understood.

2.3. Ecodesign

In its broad interpretation, Ecodesign is understood as a conceptof integrating environmental considerations in product design, andas such can be seen as an overarching term for all approachesconcerned with environmental sustainability in design. To describeits application as a design strategy, a more strict definition isadopted in this paper: “Ecodesign is a product development pro-cess that takes into account the complete life cycle of a product andconsiders environmental aspects at all stages of a process, strivingfor products, which make the lowest possible environmentalimpact throughout the product’s life cycle”(Glavic and Lukman,2007).

Ecodesign has been described in literature for more than35 years, with more widespread research and application in designpractice emerging as of 1990e1995 (Lee-Smith and Gloster, 1975;Stevels, 2001; van Hemel and Cramer, 2002). A standard forapplying this design strategy was for instance published with theUNEP Ecodesign manual (Brezet et al., 1997). Methods and toolshave since been studied and developed further (see for exampleBovea and Pérez-Belis, 2012; Byggeth and Hochschorner, 2006;

Table 1Schematic set-up of the case study with 27 student groups.

Assigned designstrategy:

Design assignment 2011:cutlery & tableware (n ¼ 12)

Design assignment 2012:coffee machine (n ¼ 15)

A. Biomimicry(n ¼ 9)

‘Biomimicry designs’(n ¼ 4)

‘Biomimicry designs’(n ¼ 5)

B. Cradle to Cradle(n ¼ 9)

‘Cradle to Cradle designs’(n ¼ 4)

‘Cradle to Cradle designs’(n ¼ 5)

C. Ecodesign (n ¼ 9) ‘Ecodesigns’ (n ¼ 4) ‘Ecodesigns’ (n ¼ 5)

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Lofthouse, 2006). To assess environmental performance related to aproduct, Ecodesign generally uses methods based on Life CycleAssessment (LCA), such as Eco-indicator analysis (Goedkoop andSpriensma, 2001). The Ecodesign tools applied in the study areincluded in Table 2 of Section 3.

As indicated, many studies have been performed on the appli-cation of different Ecodesign methods and tools. In this case study,Ecodesign is included as a ‘baseline’ strategy for exploring the ef-fects specific to Biomimicry and Cradle to Cradle.

2.4. A brief comparison

When comparing NIDS with Ecodesign, both Biomimicry andCradle to Cradle can be considered as relatively new design stra-tegies that have been predominantly developed in design practice,whereas both academia and industry contributed to Ecodesign.Consequently, Biomimicry and Cradle to Cradle have, thus far,received less scientific debate, also compared to other approachesfor sustainable design such as Product-Service Systems Design (seefor instance Mont, 2002; Tukker and Tischner, 2006).

Both Ecodesign and NIDS focus on merging environmental as-pects of sustainability in the design process (De Pauw et al., 2010).However, whereas the objective of Ecodesign is to minimize, orreduce, the environmental impact of products throughout their lifecycle, the objectives of Biomimicry as well as Cradle to Cradlechallenge designers to develop products that benefit their envi-ronment. As a result, the strategies use different criteria anddifferent terminology to define whether a product is successful. Inour study, we expect to find results that have a comparable focus onenvironmental sustainability and that reflect the differences be-tween the objectives of NIDS and Ecodesign.

3. Method

Case study research was used to obtain a thorough under-standing of the application of Biomimicry and Cradle to Cradle ascompared to Ecodesign. A comparative set-up was chosen to illu-minate findings that can be attributed to the application of Nature-Inspired Design Strategies. The data for this study have been gath-ered from two courses on ‘Sustainable Design Strategies’ for finalyear Bachelors students and forMasters students at Delft Universityof Technology, Faculty of Industrial Design Engineering (IDE).

3.1. Participants and research set-up

In total 27 student groups, 129 students, participated in theSustainable Design Strategies Course over two consecutive aca-demic years (2011 & 2012). Each group consisted of 3e6 Bachelor orMaster students.4 Most students had an IDE or other product designbackground. In order to have balanced groups and enable multi-disciplinary teamwork, students were assigned to groups accord-ing to their study background. Due to educational requirements,students from the Bachelor and Master’s program were not com-bined within groups. The groups were randomly assigned to one ofthe three design strategies.

Table 1 shows a schematic overview of the research set-up,which is based on the set-up of the course. In the course, stu-dents were taught to apply one of the three design strategies: A.Biomimicry, B. Cradle to Cradle, or C. Ecodesign for designing a

4 56 Students (12 groups) participated in 2011 and 73 students (15 groups) in2012. The course was set-up to include 5e6 students per group, but in total 13students that enrolled for the course did not start, or quit the course before thedesign assignment had started.

‘100% sustainable’ product. The ‘100%’ target was set so that thestudents were challenged to come up with a truly sustainableoutcome. In 2011, the assignment was to design “100% sustainabletableware and cutlery” for the faculty canteen, commissioned bythe fictitious caterer BiocateringNL that wished to offer a completecatering solution. In 2012, the students were asked to design a“100% sustainable coffee machine” for groups of six people,commissioned by Redbeans, a supplier of biological coffee beans.

Prior to the design assignment, the students received three half-day workshops about the design strategies led by sustainabledesign experts trained in the respective strategies. Each workshopcovered one strategy, providing the students with basic knowledgeof the theory, in the form of a lecture, followed by workshop ex-ercises to practice several strategy tools (see Table 2 for specificmethods and tools offered).

For the design assignment, an external presenter, taking theguise of a fictitious representative of the company, introduced theassignment. Each group was provided with course material of thestrategy they had been assigned and encouraged to come up witha solution using that particular design strategy. The deliverablesfor the assignment were a group poster, a report, and a presen-tation during which each group presented their design to theirpeers and jury members (teachers and the company). The stu-dents had 55 course hours to work on the assignment within aperiod of four weeks, for group work, feedback of teachers, andpresentation.

3.2. Assessing the application of the design strategies

In design methodology research, the transfer of design methodsand tools to design practice is acknowledged to be problematic (seefor example Daalhuizen and Badke-Schaub, 2011, for a discussion).Specifically for Ecodesign, Lofthouse (2006) described a variety offactors that influenced the application of tools by industrial de-signers, including time constraints, perceived benefits, and theform in which a tool conveys knowledge. As a result, a full appli-cation of the tools provided is not to be expected. In addition, thestudents involved in the case study were novices in the use of thestrategies, which may have caused some tools to be appliedincorrectly. In the pre-study with six groups, the actual applicationof the design strategies was validated, to exclude possible groupsthat did not apply the strategy they were assigned. In addition, thecurrent study with 27 groups allows for analyzing possible differ-ences in application level between the strategies.

To determine application of strategies, an inventory was made ofthe approach that the students were offered for each of the designstrategies. Per strategy,14 to 15 stepswere identified, listed inTable 2.The reports, including the grading remarks from the coaches, werereviewedusing a checklist of thedifferent steps. Each stepwasgradedeither as applied ‘correctly’, ‘partly correctly’ (i.e. part of the requiredactivity was missing or only part of the step was executed correctly),‘incorrectly’ (i.e. the step was executed, but not as instructed), or as‘not applied’. An analysis of variance (one-way independent ANOVA)was executed to analyze whether overall differences in application

Table 2Checklist for analyzing whether student groups applied a given design strategy.

Biomimicry Cradle to Cradle Ecodesign

According to the report, did the students.1 Explain the strategy 1 Explain the strategy 1 Explain the strategy2 Explain the specific method/approach 2 Explain the specific method/approach 2 Explain the specific method/approach3 Use the worksheet ‘evaluate’ (using the

life principles)3 Make a scheme for the current life cycle 3 Define the functional unit

4 Select life principles 4 Define the appropriate cycle 4 Define and quantify all current processes5 Name the design function of the assignment 5 Try to categorize all materials using the

ABC-X categorization5 Calculate eco-indicator points for all phases

in the product life cycle6 Use the Biomimicry Design Spiral questions

for distilling the design function6 Develop a vision for the ideal Cradle to

Cradle design, to be reached in 2020e20256 Present the results of the analysis

7 Use the Design Spiral questions fortranslating to biology

7 Develop a Cradle to Cradle roadmap forthe company based on their vision

7 Draw good conclusions based on their analysisregarding the aim for the new design

8 Check the AskNature database 8 Look for benefits/added value 8 Fill in the Ecodesign strategy wheel9 Discover 3 examples per function 9 Define nutrient pathways (consumption

or service, bio/tech, how cycle, howclose/renew loop)

9 Set priorities for the new design, based onthe analysis

10 Describe useful natural solutions 10 Design several solutions 10 Design several new solutions11 Brainstorm multiple solutions emulating, not

copying the solutions found in nature11 Develop these solutions based on their

roadmap11 Develop a new product (or system) that has a

significantly better score on some of the strategies12 Design several solutions 12 Develop one into a design 12 Fill in the strategy wheel for the new design

(before & after)13 Develop one into a design 13 Evaluate and test the new design 13 Define and quantify all processes14 Use the worksheet ‘evaluate’

(for the new design)14 Use the Cradle to Cradle certification

criteria for evaluation14 Calculate eco-indicator points, for all phases in

the product life cycle15 Draw conclusions based on their analysis

Methods and tools were provided by the sustainable design experts. References to specific methods and tools are, for Biomimicry (Benyus, 2013; Biomimicry 3.8, 2012;reference to the earlier versions used in the course: Biomimicry Guild, 2010; The Biomimicry Institute, 2008), for Cradle to Cradle (Bor et al., 2011; C2C Products InnovationInstitute, 2012; EPEA, 2013), and for Ecodesign (Brezet et al., 1997; OVAM, 2010).

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(i.e. total number of applied steps from a particular strategy) werestatistically significant between the three strategies (using p < .05).

To reduce the influence of the researcher, grading was per-formed by a second researcher, and reviewed by the primaryresearcher. Items for which the primary researcher did not agreewith or did not understand the motivation for a specific grade werediscussed further, and final grading was determined based onmutual agreement.

3.3. Assessing differences in design focus

In the pre-study, content analysis of the student reportsrevealed that the groups emphasized different topics in their re-ports, depending on the design strategy employed (De Pauw et al.,2012). The findings, though based on a limited number of groups,shed light on potential differences in the design focus of the groups.The differences provided insights into the effects of the differentdesign strategies. The current study expands upon these findings byreviewing possible differences in design focus, using the followingresearch question: Do the topics that the student groups focus on intheir project differ per strategy, more than they differ between groupsthat apply the same strategy?

Word frequencies in the student reports have been taken as ameasure to determine words of interest, using coding and catego-rization of the results to uncover patterns (Stemler, 2001; Weber,1990). First, an inventory was made of the top 10 of words usedmost frequently by each group. In determining the frequencies,single and plural forms of words were combined. Verbs and‘common’ English words were excluded from the top 10 frequencylist. Next, the words resulting from the inventory were categorizedinto topics the students focused on, using emergent coding. In thistechnique, the data to be coded is analyzed for establishing thecoding categories (i.e. the topics). Each category was subsequentlydefined, and all top 10 words were assigned to one of the categoriesbased on these definitions. Following the categorization, statisticalanalyses of variance were performed using one-way independentANOVA with post-hoc test (using Games-Howell Comparison) to

evaluate whether the focuses of groups varied significantly acrossstrategies.

3.4. Exploring differences in the type of solutions

The third research objective addresses the type of solution thatthe students suggest. The corresponding question has beenformulated as: Do student groups that apply NIDS more ofteninterpret the product assignment at the level of ‘function’ and/or‘needs’, as compared to groups applying Ecodesign? The pre-studyshowed that, whereas all groups proposed alternative materialsand product forms to improve sustainability performance, two outof four ‘NIDS groups’ also interpreted the assignment at a higherlevel, considering alternative ways to fulfill product functions anduser needs (De Pauw et al., 2012).

Content analysis of the student reports was used to exploredifferences in the type of solutions. After the findings from the pre-study, the following four ‘solution levels’were defined, based on the‘Model of Reasoning by Designers’ (Roozenburg and Eekels, 1995):

I. Material level. Solutions are categorized on this level whenthe designers applied alternative materials or energy sourcesto enhance product sustainability. For example, this includesthe use of bio based or recycled materials, and of renewableenergy sources.

II. Form level: This level applies when the physical appearanceof the product was altered to improve the sustainabilityperformance, but the function of the product stayed thesame. An example is changing product shape to reduce theamount of materials used.

III. Function level: At this level, the function of the product wasaltered, or new functions were included to increase productsustainability. Two types of functions are considered in theanalysis: product functions and system functions. Solutionswith new product functions may, for example, include newways of ‘portioning and transporting food’ or ’making a cupof high quality coffee’, and solutions with new system

Fig. 1. Application of the different design strategies per group, showing the level of application in four categories, based on the grading of the checklist steps. Notes:bio ¼ Biomimicry; c2c ¼ Cradle to Cradle; eco ¼ Ecodesign.

I.C. de Pauw et al. / Journal of Cleaner Production 78 (2014) 174e183178

functions may provide alternatives to the cleaning system orthe logistic system, for instance.

IV. Needs level: Project results have been categorized at theneeds level if specific needs were addressed and alternativesfor fulfilling these needs were incorporated in the design toincrease sustainability performance. In the student projects,the underlying need could for instance be described as‘providing the user with tasteful nutrients and a pleasantbreak from work’.

To detect significant differences between groups that appliedeither NIDS or Ecodesign, we analyzed results of the contentanalysis using Fisher’s exact test for small sample sizes.

For gaining qualitative insights into the possible differencesbetween strategies with respect to the sustainability measures thatwere taken, the resulting solutions and sustainability impacts wereexplored in more detail, based on the, largely qualitative, dataavailable in student reports. In addition, the researchers looked forpossible adverse impacts by checking for apparent increases in theconsumption of material and energy, for using higher-impactmaterials or energy resources, and for possible decreases inproduct lifetime or functional performance. An independent t-testwas performed for cross-comparing design focus with solutionlevels.

Table 3Categorization of all top 10 most frequently used words from the student reports into n

Topics Description Top 10 words i

Comparing Words used for comparing products andassessing differences

Current, new, q

Context Words describing the context of the product Canteen, custom(fictional client

Energy Words related to energy and energy sources Energy, solarFunction Words describing product functions, inputs

and outputsCleaning, coolin

Generic Generic words (top 10 words not categorizedelsewhere)

Figure, one

Materials Words related to material families and types Bamboo, ceramProduct Words describing products and product

performance characteristicsConcept, cup, cplate, product,

Strategy Words specific to the sustainable designstrategy used (bio ¼ Biomimicry, c2c ¼ Cradleto Cradle, eco ¼ Ecodesign), including ‘sustainable’and ‘environmental’

Biomimicry (bienvironmentallife principlea (sustainable

System Words describing the product-system, orprocesses and products in that system

Cycle, packaginsystem, transpo

a Terms counted as one word.

4. Application of the design strategies

Fig. 1 summarizes the extent to which the 27 groups applied thestrategies they were assigned. All groups applied more than 50% ofthe steps from the checklist, graded either ‘correctly’, ‘partlycorrectly’, or ‘incorrectly’. On average, Biomimicry groups appliedmost of the steps (87%), Ecodesign groups 83%, and Cradle to Cradlegroups 76%. However, the one-way independent ANOVA showedno statistically significant differences between the groups thatapplied different design strategies, with F(2, 26) ¼ 1.66, p > .05. Aseach group applied more than half of the checklist items, none ofthe groups has been excluded from further analysis.

The grading in Fig. 1 shows that on average Ecodesign groupshave a higher percentage of correctly applied steps (58%) than theNIDS groups (35%). Results differed between groups, but severalBiomimicry groups had difficulties in designing more than onesolution, whereas several Cradle to Cradle groups showed diffi-culties in developing a company roadmap for meeting their visionfor the ideal Cradle to Cradle design.

5. Differences in design focus

Table 3 shows the nine topics that resulted from the emergentcoding of the student reports, and all top 10 words (words used

ine topics (presented in an alphabetical order).

n 2011: tableware & cutlery Top 10 words in 2012: coffee machine

uantity, result, subtotal, versus New, sarista (name of an existing coffeemachine) total

er, situation, Sodexo), user

Break (‘coffee provides a break’), people,Redbeans (fictional client)Battery, energy

g, eating, food, function, waste Bean, coffee, function, ground, heat, water

Project, solution

ic, material, metal, PLA, plastic, PS Material, steel, zeoliteutlery, design, durable, item,redesign, tableware, tray, weight

Coffee machine, concept, cup (used as:‘per cup’), design, filter, grinder, part,product, redbeans-mini (product name),wired (product name)

o), Cradle to Cradlea (c2c),, impact (eco), indicator (eco),bio), nature (bio), strategy,

Cradle to Cradlea (c2c), ecocost (eco), LCA(eco), nature (bio)

g, process, production, recycling,rt

Cycle, process, production, system

Fig. 2. Topics addressed in student reports (years 2011 and 2012), based on the tenmost frequently used words in the group reports, per design strategy. Note: topicsmarked * show significant differences between the design strategies.

I.C. de Pauw et al. / Journal of Cleaner Production 78 (2014) 174e183 179

most frequently by each group) categorized according to thesetopics. For several words, the context in which they were (pre-dominantly) used in the report is added in Table 3 to clarify theirmeaning. Most topics reflect upon characteristics of the solution,some on the design activities, and four words were categorized asbeing used predominantly in a generic meaning.

Fig. 2 shows per strategy the average frequencies of top 10words per topic, as used by the groups in their reports. The resultsconfirm that the focus in the student groups’ design work differed,depending on the strategy they had been assigned, for instance forthe topics ‘comparing’, ‘context’, ‘function’, and ‘materials’.

The statistical analysis (ANOVA) showed a significant differencein variance across the design strategies for three topics (markedwith * in Fig. 2): for ‘comparing’ F(2, 24) ¼ 13.27, p < .05; for‘context’ F(2, 24) ¼ 5.26, p < .05; and for ‘function’ F(2, 24) ¼ 7.16,p < .05. For the other topics, differences were not significant(p > .05). These results indicate that group focus differed specif-ically in comparing the new product with existing ones, inregarding the functional aspects of the product, and in regardingthe context in which the product is used. On average, the top 10

Fig. 3. Topics addressed in student reports per year, showing frequencies per topic across ththat for the coffee machine in 2012 on the right.

most frequently used words of the NIDS groups referred more tofunction and context, whereas the Ecodesign groups used morewords for comparing products. The results from the post-hocanalysis (using p < .05) confirm that for the topic ‘context’ thedifference is statistically significant between groups that appliedCradle to Cradle (M ¼ 1.22) and Ecodesign (M ¼ .22), but the dif-ference between Biomimicry (M ¼ .44) and the other strategies isnot significant. The focus on product ‘function’ is significantlydifferent for groups that applied Biomimicry (M ¼ 3.11 versusM ¼ 1.22 for Cradle to Cradle and M ¼ 1.56 for Ecodesign); and thefocus on ‘comparing’ is significantly different between groups usingNIDS and Ecodesign (M ¼ .00 for Biomimicry, M ¼ .11 for Cradle toCradle, and M ¼ 1.00 for Ecodesign).

Fig. 3 depicts the focus of the groups per design assignment.Only qualitative interferences are made because of the smallernumber of groups per year. The findings match the overallfindings for the top 10 word topics ‘comparing’ and ‘context’, butnot for ‘function’. In 2012, more function-related words wereused in the student reports for each strategy, and especiallyEcodesign groups rated higher, with on average 2.8 function-related top 10 words, whereas no such words were used byEcodesign groups in 2011. Possibly, the design of the coffeemachine, with its more complicated product layout, required thestudents to more thoroughly analyze its functional processes. Ifso, the score on function-related words may not be (solely)representing the designer’s consideration of alternatives for thecoffee machine.

6. Exploring how the design strategies influence the type ofsolutions

Fig. 4 provides an impression of the designs as presented bythe student groups: for sustainable tableware and cutlery (leftcolumn), and for a sustainable coffee machine (right column). Toexplore whether the student groups applying Nature-InspiredDesign Strategies developed different types of solutions ascompared to groups that applied Ecodesign, Section 6.1 analyzesat which level(s) the students groups interpreted their assign-ment, and Section 6.2 examines what types of solutions weredeveloped for improving the sustainability performance of theproducts.

e two course years, with the assignment for tableware & cutlery in 2011 on the left, and

Fig. 4. Impression of project designs.

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6.1. Addressing materials, form, function, and needs

The 27 design solutions were assessed according to the foursolution levels described in the method’s section: Material, Form,Function, and Needs level. Table 4 shows the number of groups thatimplemented design solutions at the four levels, specified perdesign strategy and year. When a solution addressed subsequentsolution levels, these were counted in each applicable level. Forinstance, the coffee machine design of group ‘bio2’ (shown inFig. 4), incorporates a new modular product form to reduce energyuse (level II) and was designed to enhance social interaction be-tween people (level IV).

Most groups implemented solutions at the material and formlevel (I & II). Only three Biomimicry groups did not consider thematerials of the designed solution, and two groups (one usingCradle to Cradle, one using Ecodesign) maintained the originalshape of the tableware. Fewer groups addressed the assignment atthe levels of function and need: 16 (59%) and 8 (30%) respectively.

The results confirm that when students applied NIDS, theyinterpreted the design assignment at the level of ‘function’ and

Table 4Occurrence of solution levels in the project designs, showing the number of groups, per dfour solution levels.

Design strategy

Year Biomimicry Cradle to Cradle

2011 2012 Total 2011 201

Solution level (n ¼ 4) (n ¼ 5) (n [ 9)%

(n ¼ 4) (n ¼

I. Material 3 3 6 4 567%

II. Form 4 5 9 3 5100%

III. Function 3 3 6 4 367%

IV. Need 0 2 2 2 422%

‘need’ more often (p < .01, Fisher’s exact test). Overall, 19 out of27.student groups interpreted the product assignment at the levelof product function and/or needs (five groups implemented solu-tions at both levels). Of these groups,16 groups applied NIDS, whichamounts to 89% of the NIDS groups, and 3 groups applied Ecode-sign, 33% of the Ecodesign groups.

When comparing the academic years 2011 and 2012, findingsacross the two assignments confirm the main result. In both years,students assigned to NIDS were dominant in providing solutions atthe level of functions and needs (88% and 90% of the NIDS groupsversus 50% and 20% of the Ecodesign groups respectively), with theresults being more apparent in the second year.

6.2. Integrating sustainability in the design solution

As presented in the previous section, NIDS groups more oftenincorporated alternatives for product and system functions, orfulfilled user needs in a different way. But how does this approachinfluence the solutions that are developed? Here, qualitative resultsare presented on differences in the sustainability measures taken.

esign strategy and per year, implementing alternative design solutions at one of the

Ecodesign Total

2 Total 2011 2012 Total

5) (n [ 9)%

(n ¼ 4) (n ¼ 5) (n [ 9)%

(n [ 27)%

9 4 5 9 24100% 100% 89%

8 3 5 8 2589% 89% 93%

7 2 1 3 1678% 33% 59%

6 0 0 0 867% 0% 30%

I.C. de Pauw et al. / Journal of Cleaner Production 78 (2014) 174e183 181

6.2.1. Differences per solution levelAt the material level (Level I) groups from all three strategies

applied alternative, ‘low-impact’ materials to reduce the environ-mental impact of the product. Ecodesign groups selected recycledmaterials more often (5 groups), including one group that reusedsecond-hand cutlery. The three Biomimicry groups that did notconsider the materials level addressed other levels instead. One ofthe groups explained: “Whenwe started this project, we didn’t expectthis concept as an outcome. We expected that we would design aconcrete product, such as a new set of cutlery. But after our researchwe realized that the challenge of becoming sustainable could be foundon a much higher level.”

At the form level (Level II), reduction of current impacts was alsothe motivation for most changes. Interestingly, all 2012 groupsaltered the design to include manual powered processes, usuallyfor grinding the beans and also in some products for pressurizingthe water, thereby reducing energy consumption (within systemboundaries). Additionally, two groups of each strategy changedproduct shapes or introduced features to change user behavior.Ecodesign groups focused on efficiency: reducing energy con-sumption (insulation of the heated water and more efficient heatexchange) or using less material per unit, whereas, compared toother groups, Biomimicry groups were more frequent in suggestingsolutions to integrating products (plate and tray, or spoon and fork)or to use bulk packaging only. Cradle to Cradle groups did notattempt to increase the energy efficiency of the products, butinstead focused on using other energy sources, such as waste heatand renewable energy. The two groups that did not alter productshape used polished second-hand cutlery instead (Ecodesign), orfocused on the recycling of the cutlery (Cradle to Cradle).

At the function level (level III), most groups (14) designed so-lutions for the collection, recycling or composting of materials. Forinstance, one group (coded ‘c2c3’ in Fig. 4) proposed that the plastictableware be reused and, once disposed of, recycled into granulesfor the faculty 3D-printing machines. The reusable ceramic plateswere to be recycled by a local ‘Delft blue’ producer, either into newplates for the canteen or into high-end ceramics. NIDS groupsoffered specific recycling solutions three times more often (sixgroups of both strategies) than Ecodesign groups (two groups).Additionally, three Biomimicry groups designed out-of-the-boxproducts at the function level: two suggested the elimination ofcutlery in favor of ready-made food, the third implemented a coldcoffee extraction process to produce coffee with similar quality toespresso, to drastically reduce energy consumption. One Ecodesigngroup recommended that the client install solar panels on thecanteen roof, to reduce impact from the washing process of thetableware and cutlery by 29e40%, and additionally provide thefaculty with a surplus of renewable energy.

As indicated in the previous section, only NIDS groupsaddressed their assignment at the level of needs (level IV). Fourgroups developed solutions to improve the value of what peoplereceive from “getting and having a coffee”, and designed theirproduct to increase the coffee drinkers’ productivity and creativity,to “enhance group bonding”, or to provide a more social coffeebreak. Four other groups, all applying Cradle to Cradle, suggestedsolutions to improve the quality of the users’ space, by introducingplants and/or herbs into the canteen or workplace, providing re-ported benefits of “cleaning indoor air”, “providing fresh food”, upto “increasing biodiversity”.

6.2.2. Considering the risk of shifting burdensBased on the measures taken by the student groups, the re-

searchers expect adverse impacts from solutions of five groups. Oftwo designs, the weight increased considerably (1 Biomimicrygroup, 1 Cradle to Cradle), two others are expected to consume

more energy than the original machine (1 Biomimicry, 1 Cradle toCradle), and one group incorrectly applied eco-indicators, resultingin the selection of a material with higher impact (1 Ecodesigngroup). Additionally, five groups (1 Biomimicry, 2 Cradle to Cradle,and 2 Ecodesign) implemented coffee brewingmethods that can beconsidered to produce coffee dissimilar to espresso. Therefore, thereported decrease in energy use is coupled with a change inproduct quality, which was not acknowledged by the students. Oneother group (c2c4) was predominantly concerned with solutionsthat the students considered necessary to provide a beneficial workbreak. No adverse impacts of their design are anticipated, but themajority of sustainability issues of the design were neglected.

6.2.3. Focus on environmental sustainabilityAs described in Section 2.4, the three strategies have their scope

or focus on the environmental impacts associated with the product,as opposed to social impacts. Nevertheless, the students were askedto design a fully sustainable solution. The results indicate thatindeed little to no attention was paid to social sustainability issues.The groups that did consider social structures, considered the usersof their product, for instance by facilitating a ‘social coffee break’.Some groups referred to the social aspects incorporated by theirclient (fair trade food/coffee), but did not consider these issues inthe design of their product. One group referred to Corporate SocialResponsibility, but only when evaluating their design.

7. Discussion

Based on the significant differences in the design focus, solutionlevels, and specific designs that are related to the design strategies,we discuss below how the Nature-Inspired Design Strategiesincluded in this study may have helped the students in their aim todesign ‘sustainable products’.

7.1. How design strategies can shift design focus

The differences in the design focus of groups using either Bio-mimicry, Cradle to Cradle, or Ecodesign, point to the influence ofdesign strategies. Biomimicry, as taught in the course, asked thedesign students to translate the assignment to a functional level, inorder to find useful examples in nature, thereby ‘inviting’ them toreconsider current product solutions. Cradle to Cradle challengedthe groups to generate ‘beneficial effects’, which coincides with thecontext-specific systems focus adopted by the majority of thesegroups. Conversely, Ecodesign focused the groups on comparing,analyzing the ‘hot spots’ in current products, which provided thestudents with the basis for reducing the product’s environmentalimpacts.

Compared to the groups that applied Ecodesign, the strongerfocus of the NIDS groups on the product context (people, companiesand circumstances interrelated to the product-system) signifies theinfluence of guiding design principles in the design process. BothBiomimicry and Cradle to Cradle have design principles and toolspointing to the value of developing solutions that are ‘diverse’,specifically tuned to their (local) environment (Benyus, 1997;McDonough and Braungart, 2002). Earlier case-studies did notaddress the application of these principles, which may explain whythe findings were not observed prior to this research.

7.2. How NIDS can affect the level at which the assignment isinterpreted

The results of this study indicate that Biomimicry and Cradle toCradle help design students to consider solutions at a ‘broader’level, including alternatives for fulfilling product functions, system

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functions, or user needs. As to how NIDS can affect the solutionlevel, we draw on the cross-comparison of the design focus andsolution levels. On average, groups that interpreted the assignmentat the level of function and/or needs, more often used ‘contextwords’ frequently in their reports (M ¼ .89, SE ¼ .19) than groupsthat did not address these levels (M ¼ 0), with a significant dif-ference between the two types of groups (t-test, with t-statistic ¼ �4.82, p < .01). The opposite relation was found for thefrequent use of ‘comparing words’ (with M ¼ .16 for groups thataddressed the level of function and/or needs, versus M ¼ .88 forgroups that did not address these levels) being also significant (t-statistic ¼ 2.33, p < .05).

All 13 groups that used context-related words frequently (11NIDS groups and 2 Ecodesign groups) addressed the project at thelevel of function and needs, and nine of them also proposed acontext-specific solution (such as a recycling infrastructure coupledto specific local companies). Supporting integration of the productcontext may be a distinct feature of nature-inspired design forenhancing the sustainability of the system. This finding corre-sponds to that of a parallel case study conducted at a design agencythat applied Cradle to Cradle (De Pauw et al., 2013). Secondly, thereported focus of Ecodesign groups on comparing products mayprovide additional understanding into the differences in the de-signs. The time spent on analyzing existing products at the start of aproject, may have limited the time the students had available toconsider more-encompassing solutions. In contrast, NIDS offeredchallenging ‘absolute’ design principles, which may have encour-aged the students to widen their solution space in their effort tomeet the principles. Likewise, the office chair case as described byLee and Bony (2009) and Rossi et al. (2006) illustrates how ‘abso-lute’ limitations, posed by the Cradle to Cradle strategy, allowedmore time to be spent on finding solutions within these boundaryconditions. Further research will be needed to illuminate theserelations.

7.3. Resulting differences in solutions

More out-of-the-box designs emerged from groups that appliedNIDS, with examples such as a canteen that no longer uses cutlery,or that reuses cutlery as material for 3D printing, or a coffee ma-chine using cold-water coffee extraction. Although earlier casestudies on Biomimicry and Cradle to Cradle offer no comparisonbetween different strategies, the products partly match the classi-fication of out-of-the-box designs: the Biomimicry cases describedby Reap et al. (2005) and Montana-Hoyos (2008), and the Cradle toCradle office chair illustrate functional innovations. Furthermore,the Cradle to Cradle studies report a shift to close cooperation withsuppliers, although only the graduation project (Bakker et al., 2009)describes the development of new system functions. Innovations inmeeting user needs were not reported.

Addressing the design assignment at the level of function andneeds allows for the development of more radical solutions.However, if, and to what extent NIDS tap into this potential andgenerate superior sustainability performance, could not beassessed from the results of the design assignments. The resultssuggest that NIDS influence students to set more ambitious goalsand objectives. The proposed functional innovations may drasti-cally reduce the environmental impact of the designs, and theproduct-service-systems may have a similar effect. However,quantitative data would be needed to perform a life-cycle basedanalysis of these solutions on a systems level to determine overallimpact on environmental sustainability. In addition, for comparingthe differences across strategies, the analysis should include anassessment of the context-specific environmental effects of thesolutions. According to Bor et al., LCA-based tools are currently

incapable of capturing the environmental benefits of Cradle toCradle (Bor et al., 2011).

This case study demonstrated that groups applying NIDS, ascompared to Ecodesign groups, run a higher risk of introducingadverse impacts with their solutions. Whereas the design princi-ples of Biomimicry and Cradle to Cradle seem to offer a strategicalternative to the hot-spot analysis in Ecodesign, these principlesoffer no alternative for quantitative product evaluation tools, suchas those provided in Ecodesign.

8. Conclusions

In this case study, two Nature-Inspired Design Strategies, Bio-mimicry and Cradle to Cradle, have been compared with Ecodesignusing results from students’ work in sustainable product design.Our analysis showed significant differences in the design focus ofthe student groups, depending on the strategy they applied.Additionally, this study confirms the finding from a pre-study, thatNIDS help students to consider more solution levels (De Pauw et al.,2012). Whereas most groups applied different materials andchanged product shapes to improve the design, the majority of thegroups that applied NIDS (over 80%) also included solutions thatprovide alternative and new product or system functions, orincluded new ways to fulfill user needs. In contrast, only one thirdof the groups applying Ecodesign suggested such solutions.

As to how NIDS generate these results, this study revealed thatNIDS encourage students to include solutions found within thespecific context of the product-system (people, companies and cir-cumstances interrelated to the product-system). In comparison,groups using Biomimicry have taken a more functional approach,whereas Cradle to Cradle challenged the students to incorporate‘beneficial impacts’ - impacts that benefit the (eco) system inwhichthe product functions.

We are aware that the findings of this case study are to beinterpreted with caution when real-life design practice is consid-ered. The students performed the design assignment for educa-tional purposes, had little or no previous experience in theapplication of the strategies, and were trained in each of the designstrategies via workshops. They were assigned to a group and askedto apply a specific strategy, whereas in practice, designers adopt thestrategy they see fit to a specific design challenge. Furthermore, werecognize the limitations of this study due to the small total samplesize, and used statistical tests suited to this sample to uncoversignificant differences between the three strategies. In a subse-quent study, we aim to compare the results of this study with thoseobtained from ‘real-life cases’, to explore the applicability of thefindings for design practice.

Nevertheless, we have been able to show that Biomimicry andCradle to Cradle provide design students with an approach toproduct design that is distinct from Ecodesign in several respects.For the cases studied, the strategies were particularly equipped tobroaden the designers’ solution space and to generate solutions at afunction or system level. However, neither of the strategiescurrently offers quantitative design tools (as Ecodesign does) forevaluating the environmental impact of the solutions across theproduct life cycle. This induces the risk of unforeseen impacts if thedesign strategies are applied in isolation.

Acknowledgments

Wewish to thank all students participating in the 2011 and 2012courses for providing data and sharing their insights, and C.A.Bakker for the opportunity to co-develop and study the results ofthe Sustainable Design Strategies course.

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References

Bakker, C.A., Wever, R., Teoh, C., De Clercq, S., 2009. Designing Cradle-to-Cradleproducts: a reality check. Int. J. Sust. Eng. 3, 2e8.

Baumeister, D., Tocke, R., Dwyer, J., Ritter, S., Benyus, J., 2013. Biomimicry ResourceHandbook: a Seed Bank of Best Practices, First Public Print ed. Biomimicry 3.8,Missoula.

Benyus, J., 1997. Biomimicry: Innovation Inspired by Nature. William Morrow & Co,New York.

Benyus, J.M., 2013. A Biomimicry Primer, Resource Handbook. Biomimicry 3.8.Biomimicry 3.8, 2012. Biomimicry Design Lens, p. Collection of Biomimicry

Diagrams.Biomimicry Guild, 2010. Biomimicry: Innovative Solutions Inspired by Nature.

Biomimicry Guild, Helena, USA.Bjørn, A., Hauschild, M.Z., 2012. Absolute versus relative environmental sustain-

ability. J. Ind. Ecol. Early view.Bor, A.-M., Hansen, K., Goedkoop, M., Rivière, A., Alvarado, C., Wittenboer, W.v.d,

2011. Usability of Life Cycle Assessment for Cradle to Cradle purposes. NLAgency, Utrecht.

Bovea, M.D., Pérez-Belis, V., 2012. A taxonomy of Ecodesign tools for integratingenvironmental requirements into the product design process. J. Clean. Prod. 20,61e71.

Brezet, J., van Hemel, C. (Eds.), 1997. Ecodesign, a Promising Approach to SustainableProduction and Consumption. United Nations Environmental Programme(UNEP), Paris.

Byggeth, S., Hochschorner, E., 2006. Handling trade-offs in Ecodesign tools for sus-tainable product development and procurement. J. Clean. Prod. 14, 1420e1430.

C2C Products Innovation Institute, 2012. Cradle to Cradle Certified Product Stan-dard, Version 3.0. McDonough Braungart Design Chemistry.

Cross, N., 2000. Engineering Design Methods: Strategies for Product Design, thirded. John Wiley & Sons, LTD, Chichester.

Daalhuizen, J., Badke-Schaub, P., 2011. The use of methods by advanced beginnerand expert industrial designers in non-routine situations: a quasi-experiment.Int. J. Prod. Dev. 15, 54e70.

De Pauw, I., Kandachar, P., Karana, E., Peck, D., Wever, R., 2010. Nature inspireddesign: strategies towards sustainability. In: Wever, R., Quist, J., Tukker, A.,Woudstra, J., Boons, F., Beute, N. (Eds.), Proceedings of the 2010 ERSCP-EMSUconference Delft, The Netherlands, October 25e29, 2010, pp. 1e21.

De Pauw, I., Karana, E., Kandachar, P., 2012. Nature-inspired design strategies. In:Sustainable Product Development: a Case-Study of Student Projects,Proceedings of the 12th International Design Conference DESIGN 2012,pp. 787e796.

De Pauw, I., Karana, E., Kandachar, P., 2013. Cradle to Cradle in Product Develop-ment: a Case Study of Closed-Loop Design, Re-engineering Manufacturing forSustainability. Springer, Heidelberg, pp. 47e52.

EPEA, 2013. Cradle to Cradle.

Glavic, P., Lukman, R., 2007. Review of sustainability terms and their definitions.J. Clean. Prod. 15, 1875e1885.

Goedkoop, M., Spriensma, R., 2001. The Eco-indicator99: a Damage OrientedMethod for Life Cycle Impact Assessment: Methodology Report.

Lee-Smith, D., Gloster, M., 1975. Eco-design project. DMG-DRS J. 9, 259e264.Lee, D., Bony, L.J., 2009. Cradle-to-Cradle Design at Herman Miller: Moving Toward

Environmental Sustainability. Harvard Business School Technology & Opera-tions Mgt. Unit. (HBS Case No. 607-003).

Lofthouse, V., 2006. Ecodesign tools for designers: defining the requirements.J. Clean. Prod. 14, 1386e1395.

McDonough, W., Braungart, M., 2002. Cradle to Cradle: Remaking the Way we MakeThings. North Point Press, New York.

McDonough, W., Braungart, M., Anastas, P.T., Zimmerman, J.B., 2003. Applying theprinciples of green engineering to Cradle-to-Cradle design. Environ. Sci. Tech-nol. 37, 434Ae441A.

Mont, O.K., 2002. Clarifying the concept of producteservice system. J. Clean. Prod.10, 237e245.

Montana-Hoyos, C., 2008. A proposal of biomimicry, human needs and ecodesign inan integrative method to teach sustainability within industrial design educa-tion. Des. Res. J. Des. Res. Assoc. Jpn., 86e93.

OVAM, 2010. Ecolizer2.0. OVAM, Mechelen.Reap, J., Baumeister, D., Bras, B., 2005. Holism, Biomimicry and Sustainable Engi-

neering. ASME 2005 International Mechanical Engineering Congress andExposition (IMECE2005) ASME, pp. 423e431.

Reijnders, L., 2008. Are emissions or wastes consisting of biological nutrients goodor healthy? J. Clean. Prod. 16, 1138e1141.

Roozenburg, N.F.M., Eekels, J., 1995. Product Design: Fundamentals and Methods.John Wiley & Sons, Chichester.

Rossi, M., Charon, S., Wing, G., Ewell, J., 2006. Design for the next generation:incorporating Cradle-to-Cradle design into Herman Miller products. J. Indust.Ecol. 10, 193e210.

Stemler, S., 2001. An overview of content analysis. Pract. Assess. Res. Eval. 7, 137e146.

Stevels, A., 2001. Application of Ecodesign: Ten Years of Dynamic Development.EcoDesign 2001: Second International Symposium on EnvironmentallyConscious Design and Inverse Manufacturing, 2001, pp. 905e915.

The Biomimicry Institute, 2008. AskNature.Tukker, A., Tischner, U., 2006. Product-services as a research field: past, present and

future. Reflections from a decade of research. J. Clean. Prod. 14, 1552e1556.van Hemel, C., Cramer, J., 2002. Barriers and stimuli for Ecodesign in SMEs. J. Clean.

Prod. 10, 439e453.Vincent, J.F.V., 2009. Biomimetics e a review. Proc. Inst. Mech. Eng. Part J. Eng. Med.

223, 919e939.Volstad, N.L., Boks, C., 2012. On the use of Biomimicry as a useful tool for the

industrial designer. Sust. Dev. 20, 189e199.Weber, R.P., 1990. Basic Content Analysis. Sage Publications, Incorporated.