Thierry Rabilloud
email: thierry.rabilloud@cea.fr

Pierre Lescuyer

The proteomic to biology inference, a frequently overlooked concern in the interpretation of proteomic data: a plea for functional validation

Keywords: translational modifications, comparative proteomics, protein identification, two-dimensional gel electrophoresis

Abstract

Proteomics will celebrate its 20th year in 2014. In this relatively short period of time, its has invaded most areas of biology and its use will probably continue to spread in the future. These two decades have seen a considerable increase in the speed and sensitivity of protein identification and characterization, even from complex samples. Indeed, what was a challenge twenty years ago is now little more than a daily routine. Although not completely over, the technological challenge now makes room to another challenge, which is the best possible appraisal and exploitation of proteomic data to draw the best possible conclusions on a biological point of view. The point developed in this paper is that proteomic data are almost always fragmentary. This means in turn that although better than a mRNA level, a protein level is often insufficient to draw a valid conclusion on a biological point of view, especially in a world where post-translational modifications play such an important role. This means in turn that transformation of proteomic data into biological data requires an important intermediate layer of functional validation, i.e. not merely the confirmation of protein abundance changes by other methods, but a functional appraisal of the biological consequences of the protein level changes highlighted by the proteomic screens. Many if not most proteomic studies aim at comparing at least two different biological states to find differences in protein expression, most often quantitative differences. The conceptual rationale of these studies is based on homeostasis at the cell and organism levels, so that the proteins that change are perceived as important and linked to the differences in phenotypes between the various states compared. This concept is used by all functional -omics and is true for physiology or fundamental cell biology. In a nutshell, the concept is that changes observed with -omics translate into biologically relevant events or mechanisms.

When proteomics is applied as the discovery tool for such comparative purposes, two major hurdles must be overcome.

The first hurdle is the one of protein inference, i.e. how to convert mass spectrometry (MS) signals acquired on digestion peptides, or, in the case of gel-based proteomics, a combination of MS signals and image intensities, into a list of modulated proteins. MS data processing to obtain trustful lists of identified and relatively quantified proteins has been the subject of intense debate and investigation and was at the origin of proteomics data publication guidelines already almost 10 years ago [START_REF] Carr | The need for guidelines in publication of peptide and protein identification data: Working Group on Publication Guidelines for Peptide and Protein Identification Data[END_REF][START_REF] Bradshaw | Reporting protein identification data: the next generation of guidelines[END_REF][START_REF] Wilkins | Guidelines for the next 10 years of proteomics[END_REF]. As a positive consequence of those guidelines, no proteomics dataset can today be published without false discovery rate estimation at the peptide level, although the peptide to protein inference problem can still not be considered as a straightforward issue [START_REF] Nesvizhskii | Interpretation of shotgun proteomic data -The protein inference problem[END_REF]. Concerning quantitative results extraction from MS data, the guidelines are still evolving, obviously as the field is not as mature as MS/MS identification interpretation. Overall, those guidelines have participated in significantly increasing the quality of published proteomics datasets, especially in the handful of specialized proteomics journals. Although not fully settled, this first hurdle will not be further commented in this paper.

The second hurdle is the protein to biology inference and it is felt that the problems linked to this step are often overlooked, leading possibly to data over-or misinterpretation and thus to misleading conclusions. We would therefore like to comment on this biology inference problem and suggest some guidance, based on published examples, to circumvent possible interpretation issues.

Although shotgun proteomics and gel-based proteomics behave differently in the protein to biology inference problem, the common root shared by all proteomic setups is that the characterization of the protein changes is most often not sufficient to draw solid biological conclusions directly. First, protein identification is based on subsets of peptides and information for correct characterization of protein family members or protein isoforms (PTM, cleavage) may be missing. Second, proteomic analysis rarely identifies all protagonists from a given metabolic pathway or functional network, and information on modulating or limiting factors is often lacking. Third, even assuming reliable identification and quantification, measuring a change in protein level does not always tell much about the biological effect, particularly when considering that many proteins have multiple functions or exist as active and inactive isoforms. In all these situations, the problem is the same: how to draw reliable conclusions on biological processes from sketchy and incomplete data? This should obviously not been considered as an irreducible flaw, and proteomics offers great chances for solving biological and biochemical questions. It rather means that the strengths and limitations of the toolbox must be clearly understood to obtain the greatest solid benefit. In the case of shotgun proteomics, the most frequent situation is that proteins are identified by only a few peptides, covering a very low and non-uniform portion of the protein sequence. From these few peptides, a change in the biological activity represented by the protein is generally inferred, but this can be a strong overinterpretation. One reason is that the overall length of the protein is not documented. It is very rare that the identified peptides are positioned close to the termini of the proteins, so that it is not possible to know whether the complete protein or only a fragment is detected. This is trivial in gel-free proteomics, where only peptides are analyzed without any prior separation at the protein level. This is however also true in the GeLC setup, where SDS-PAGE of proteins is used as the first separation stage, followed by in-gel digestion and LC/MS/MS of the peptides [START_REF] Schirle | Profiling core proteomes of human cell lines by one-dimensional PAGE and liquid chromatography-tandem mass spectrometry[END_REF]. This is due to the fact that the resolving power of SDS PAGE is not fully used, as a limited number of bands are usually cut in a shortly migrated gel lane. Just to take an example, if a gel able to separate proteins between 20 and 200 kDa is cut in ten fractions, the ten fractions will cover the following Mw ranges from 20-25 kDa to 159-200 kDa, through windows such as 40-50kDa or 80-100kDa. This is due to the logarithmic law governing the relationship between migration distance and molecular mass [START_REF] Weber | The reliability of molecular weight determinations by dodecyl sulfate-polyacrylamide gel electrophoresis[END_REF]. The consequence is a 20% inaccuracy in the protein mass determination for each fraction, i.e. an important room for error. It has been shown that forms differing even moderately in molecular mass can have quite different properties, e.g. on an immunological or clinical point of view [START_REF] Charrier | Differential diagnosis of prostate cancer and benign prostate hyperplasia using two-dimensional electrophoresis[END_REF][START_REF] Hong | Identification of a Specific Vimentin Isoform That Induces an Antibody Response in Pancreatic Cancer[END_REF]. Protein cleavage represents indeed a very complex way of regulation of protein activity, as exemplified by trypsin itself. After zymogen activation, which releases the active protease, trypsin autolyses progressively, producing various cleavage products with trypsin activity [START_REF] Ru | Active Products of Porcine Trypsin after Autolysis[END_REF][START_REF] Maroux | On Some Autolyzed Derivatives of Bovine Trypsin[END_REF], no proteolytic activity at all [START_REF] Smith | Pseudotrypsin -a Modified Bovine Trypsin Produced by Limited Autodigestion[END_REF], or with no trypsin activity but a low chymotrypsin activity [START_REF] Keildlouha | Proteolytic Activity of Pseudotrypsin[END_REF]. This example underlines the difficulty to infer the actual function of a protein from only a small subset of peptides, and the tendency to neglect the molecular mass information [START_REF] Aebersold | Western Blots vs. SRM Assays: Time to turn the tables?[END_REF] is likely to introduce further difficulties in the functional interpretation of the proteomic data.

More generally, it is now well-recognized but still underestimated that PTM represent a very important way of modulating protein activity, and this statement goes much beyond the classical example of phosphorylation. Acetylation [START_REF] Zhao | Regulation of Cellular Metabolism by Protein Lysine Acetylation[END_REF][START_REF] Wang | Acetylation of Metabolic Enzymes Coordinates Carbon Source Utilization and Metabolic Flux[END_REF], methylation [START_REF] Ivanov | Methylation-acetylation interplay activates p53 in response to DNA damage[END_REF], glycosylation [START_REF] Yang | Modification of p53 with Olinked N-acetylglucosamine regulates p53 activity and stability[END_REF], or prenylation [START_REF] Maltese | Posttranslational Modification of Proteins by Isoprenoids in Mammalian-Cells[END_REF] have been documented to modulate strongly protein localization and/or activity. Even minimal chemical modifications, such as oxidation, can result in protein inactivation [START_REF] Rabilloud | Proteomics analysis of cellular response to oxidative stress -Evidence for in vivo overoxidation of peroxiredoxins at their active site[END_REF][START_REF] Hwang | Oxidative modifications of glyceraldehyde-3-phosphate dehydrogenase play a key role in its multiple cellular functions[END_REF][START_REF] John | Complete sequencing and oxidative modification of manganese superoxide dismutase in medulloblastoma cells[END_REF]. Thus, the absence of knowledge of the precise modification profile of a protein can result in a misleading interpretation of the observed quantitative changes. Indeed, an increase in a protein amount can reflect not a boost in the protein activity, but just an attempt of the cells to maintain a biological function that has been altered, e.g. by an oxidation (e.g. in [START_REF] Chevallet | Regeneration of peroxiredoxins during recovery after oxidative stress: only some overoxidized peroxiredoxins can be reduced during recovery after oxidative stress[END_REF]). Conversely, an activating PTM occurring on a protein (e.g. by phosphorylation or acetylation) can boost a protein function at constant level [START_REF] Zhao | Regulation of Cellular Metabolism by Protein Lysine Acetylation[END_REF][START_REF] Wang | Acetylation of Metabolic Enzymes Coordinates Carbon Source Utilization and Metabolic Flux[END_REF] and may even compensate a decrease in protein level.

It can be argued that the documentation provided in shotgun proteomics is comparable to the indirect one given by transcriptomics, or to the one obtained through the epitopes recognized in a sandwich ELISA. This is certainly true, but it should be kept in mind that ELISA are rarely used as discovery tools but rather as scoring tools, and that transcriptomic data are now not considered in most journals as a sufficient evidence by themselves. Put bluntly, if not provocatively, the limited characterization afforded by shotgun proteomics, when used in a generic discovery mode, does not usually offer by itself sufficient information to infer a change in the protein activity, and thus to correlate reliably the proteomic data to biology. This caveat does not apply only to proteomics but to most omics, and just reflects an often overlooked lesson of genomics, i.e. that complex genomes are not that complex in terms of range of gene products expressed. For example, the human genome contains ca. 21,000 protein-coding genes [START_REF] Clamp | Distinguishing protein-coding and noncoding genes in the human genome[END_REF], to produce an organism with ca. ten thousand billion cells [START_REF] Bianconi | An estimation of the number of cells in the human body[END_REF]. This is only 10% more protein-coding genes than the worm genome, producing an organism with 1000 cells [START_REF] Hillier | Genomics in C. elegans: so many genes, such a little worm[END_REF], and less than four times the number of protein-coding genes of the unicellular yeast genome [START_REF] Lin | Re-annotation of protein-coding genes in the genome of saccharomyces cerevisiae based on support vector machines[END_REF]. This means in turn that the increase in regulations complexity is likely to hide not in the number of gene products, but in combinatorial regulations downstream, i.e. at the protein interaction level and at the PTM combinatorial level, both being of course intertwined. These downstream layers of regulations can produce paradoxical results when compared to mRNA or protein levels alone. This can be due to various modifications, including protein cleavages as mentioned above, but also to stoichiometry issues in protein complexes. As an example, when present in excess, a scaffolding subunit in a multiprotein complex can lead to a decreased activity by decreasing the proportion of fully assembled and fully active complexes. Thus, it should be kept in mind that a direct inference from a protein level to a biological effect can be an overspeed conclusion.

Although different, the situation in 2D gel-based proteomics is problematic as well. 2D gels provide a rather accurate characterization of the molecular mass and pI of the protein of interest, and will allow determining whether it is the full-length protein or a fragment that is investigated. Moreover, multiple PTM often result into multiple spots [START_REF] Anderson | Covalent Protein Modifications and Gene-Expression Changes in Rodent Liver Following Administration of Methapyrilene -a Study Using 2-Dimensional Electrophoresis[END_REF], so that it is often possible to know which form of the protein is changing. Knowing the exact nature and position of the PTM can however represent a difficult task [START_REF] John | Complete sequencing and oxidative modification of manganese superoxide dismutase in medulloblastoma cells[END_REF][START_REF] Wagner | A method for detection of overoxidation of cysteines: peroxiredoxins are oxidized in vivo at the active-site cysteine during oxidative stress[END_REF], at least in bottom-up proteomics. Last but not least, 2D gel-based proteomics also shows the unique ability to compare protein abundances within one sample due to the uniformity of protein staining [START_REF] Maass | Efficient, global-scale quantification of absolute protein amounts by integration of targeted mass spectrometry and two-dimensional gel-based proteomics[END_REF]. This said, the main danger of overinterpretation in 2D gel-based proteomics is embedded in the way 2D gels are used to select quantitative changes. Most often, changes are detected on a spot by spot basis, so that proteins appearing as multiple spots pose the problem of taking a part for the whole. A typical example is malate dehydrogenase, which appears as three spots (Figure 1). In some circumstances, only the most acidic (i.e. most modified form) is induced, the other major spots being constant. In the classical 2D gel-based proteomic setup, the increased spot is excised, its nature determined by mass spectrometry, and an increase in malate dehydrogenase is deduced. On a purely quantitative point of view, this deduction is a nonsense, as the minor spot represents only a few percent of the total malate dehydrogenase. It happens however that malate dehydrogenase activity is strongly modulated by PTM such as acetylation [START_REF] Zhao | Regulation of Cellular Metabolism by Protein Lysine Acetylation[END_REF], so that this minor spot may bear an important part of the malate dehydrogenase activity and its change may be relevant, functionally speaking. In this context, it is impossible to know which is the real functional inference to be made on the sole basis of the proteomic data.

In conclusion, no discovery proteomic setup is devoid of interpretation biases at the stage of drawing biological inference from proteomic data. Various parameters, such as the addressed biological question, study design, sample type and processing, will have an impact on data interpretation and must be carefully defined. Nevertheless, and independently of these aspects, validation by independent and preferably orthogonal techniques appears as an unavoidable process to consolidate the proteomic data. This validation can be divided in two distinct parts. The first stage of validation deals with the problem of protein inference and fragmentary data and aims at confirming the identity of the protein species/isoform/PTM identified from shotgun experiments or 2D gel-based proteomics. It will also confirm quantitative data from proteomic experiments. This first stage of verification is usually performed with independent methods like immunoblotting (e.g. in [START_REF] Martins-De-Souza | Proteome analysis of the thalamus and cerebrospinal fluid reveals glycolysis dysfunction and potential biomarkers candidates for schizophrenia[END_REF] ) , qPCR, or SRM (e.g. in [START_REF] Thingholm | Characterization of human myotubes from type 2 diabetic and nondiabetic subjects using complementary quantitative mass spectrometric methods[END_REF] ).

Although important for securing the protein identifications and the quantitative changes observed, this validation at the sole protein level is often not sufficient to infer biological changes. A second stage of validation is requested to address the question of functional inference. In most cases, what is inferred from the protein quantitative differences is a change in the activity of the protein. Due to the numerous caveats discussed above, this has to be experimentally verified, and the functional validation of proteomic data can take various forms. The objective of this article is clearly not to review all of them, but to provide some examples, starting with siRNA, which can be extremely a valuable tool for investigating cell biology processes [START_REF] Chan | Identification of differentially regulated secretome components during skeletal myogenesis[END_REF]. In many cases, however, a change in activity can be directly or indirectly documented by a biochemical validation. This can be an enzyme assay, a metabolite assay [START_REF] Martins-De-Souza | Proteome analysis of the thalamus and cerebrospinal fluid reveals glycolysis dysfunction and potential biomarkers candidates for schizophrenia[END_REF], or an indirect assay based on pharmacological inhibitors [START_REF] Triboulet | Molecular responses of mouse macrophages to copper and copper oxide nanoparticles inferred from proteomic analyses[END_REF]. The example of the pyruvate assay used in the frame of schizophrenia by Martinsde-Souza et al. also illustrates an important point, which is that specificity should not be mistaken for relevance. Since the description of the "déjà vu in proteomics" [START_REF] Petrak | Deja vu in proteomics. A hit parade of repeatedly identified differentially expressed proteins[END_REF][START_REF] Wang | Generally detected proteins in comparative proteomics -A matter of cellular stress response?[END_REF], there is a tendency to consider that changes in metabolic enzymes represent a general adaptation of cells that has little to do with relevant cellular responses. This lecture grid is strongly influenced by the biomarker perspective, where specificity and selectivity are essential. Although not specific, changes in metabolic enzymes can be critical on a mechanistic point of view. Impaired carbohydrate metabolism in schizophrenia is a good example [START_REF] Fucetola | Age-and dosedependent glucose-induced increases in memory and attention in schizophrenia[END_REF][START_REF] Newcomer | Glucose-induced increase in memory performance in patients with schizophrenia[END_REF], as well as sterol metabolism for immune control and inflammatory diseases [START_REF] Zeiser | Preemptive HMG-CoA reductase inhibition provides graft-versus-host disease protection by Th-2 polarization while sparing graft-versus-leukemia activity[END_REF][START_REF] Zeiser | Regulation of different inflammatory diseases by impacting the mevalonate pathway[END_REF]. In this frame, the added value of proteomics is both to point out the pathway of interest (and thus pharmacological entry points to modulate it) and the proteins modulated within the pathway (e. g. in [START_REF] Steiner | Proteomics to display lovastatin-induced protein and pathway regulation in rat liver[END_REF][START_REF] Steiner | Cholesterol biosynthesis regulation and protein changes in rat liver following treatment with fluvastatin[END_REF] for statins). The latter example points out to another trend in proteomics that has developed due to the specific features of shotgun proteomics. In general, shotgun proteomics (or transcriptomics) delivers a huge list of modulated proteins, generated by automated in silico database search, so that individual validation becomes impossible. Researchers usually resort to pathway analysis to make the most of such massive data. These tools are helpful since they can provide some hints for further investigation of some of the identified proteins. However, the too frequent weak point is that the outcome of pathway analyses is not validated by additional experiments, so that the reader is left short of solid data. There are happy exceptions however, as shown by an example on the proteomic analysis of Cornelia de Lange syndrome [START_REF] Gimigliano | Proteomic Profile Identifies Dysregulated Pathways in Cornelia de Lange Syndrome Cells with Distinct Mutations in SMC1A and SMC3 Genes[END_REF]. This study highlighted a variety of proteins with no obvious link between themselves, but on the one hand oxidative stress was suspected and on the other hand the pathway analysis converged to Rad21 and c-myc. The authors validated both proteomic-driven hypotheses by a combination of western blotting, chromatin immunoprecipitation and qPCR. By doing so they closed the circle on both hypotheses and ended up with solid data that can be convincing much beyond the proteomic community.

In conclusion, proteomic data are often not precise enough to make valid biologically inferences directly. Thus, targeted validation by non proteomic methods seems indispensable to warrant the validity and functional importance of the findings made by proteomics. It seems to us that ten years after securing the quality of the MS data, tending to this goal of securing the biological relevance should be the next objective for the proteomic literature.

The authors have declared no conflict of interest

Figure 1 :

 1 Figure 1: RAW 264 macrophage cells were cultured either under control conditions or treated for 24 hours with 0.11mM zinc sulfate. The cellular proteins were extracted in a urea-thiourea buffer, and separated by 2D electrophoresis (1st dimension linear pH gradient from 4 to 8, 2nd dimension 10% acrylamide gel). Only the zones containing the malate dehydrogenase (Swissprot P14152) spots are shown. When the control (Panel A) and zinc-treated (panel B) conditions are compared by computerized image analysis (Delta 2D software) a significant change (reduction by zinc treatment) is found in spot a, but not in spots b and c, nor in the Hox2 spot.


Francis Rasamoelina
email: francis.rasamoelina@ensam.eu

Carole Bouchard
email: carole.bouchard@ensam.eu

Améziane Aoussat

Towards a kansei-based user modeling methodology for ecodesign

Keywords: Kansei design, experience design, user modeling, user centered design, Eco-design

We propose here to highlight the benefits of building a framework linking Kansei Design (KD), User Centered Design (UCD) and Eco-design, as the correlation between these fields is barely explored in research at the current time. Therefore, we believe Kansei Design could serve the goal of achieving more sustainable products by setting up an accurate understanding of the user in terms of ecological awareness, and consequently enhancing performance in the Eco-design process. In the same way, we will consider the means-end chain approach inspired from marketing research, as it is useful for identifying ecological values, mapping associated functions and defining suitable design solutions. Information gathered will serve as entry data for conducting scenario-based design, and supporting the development of an Eco-friendly User Centered Design methodology (EcoUCD).

INTRODUCTION

This paper aims to achieve two objectives: firstly it reviews the literature in order to find approaches from various topics that may be relevant to linking the fields of Eco-design, User Centered Design and Kansei Design. And next, it compiles these ideas and proposes a theoretical model that describes this particular association. Thus we will provide here a brief overview of the notable breakthroughs in these areas and review the most relevant technologies developed in terms of user involvement. We will focus especially on trends in modeling that allow integration with the field of Ecodesign. Thus, this paper is divided into six parts, ranging from the general to the specific. Part 1 presents an overview of the analysis of the state of the art results. Part 2 introduces the pathway with a general assertion on sustainability and its connection with Eco-design and Green Kansei, and we will discuss what is known as Eco-design. Part 3 evaluates the capabilities of Ecodesign approaches to integrate users. Part 4 focuses on the user and makes a general statement on the current principles for integrating and evaluating users in user centered design studies. Part 5 goes further toward an advanced definition of users by asserting Kansei-based factors that we call Eco-Kansei, then describing what is known as Green Kansei for Eco-design. And finally, we will conclude on part 6 by suggesting a new theoretical model as an initial framework of attempting to merge the processes of Kansei Design and User Centered Design and Eco-design.

GENERAL OVERVIEW

To begin with, we will start by giving an overview of the results of a state of the art review. Indeed, the basic context of our work is clearly considered as cross disciplinary and requires a wide and macro vision of the subject. The related state of the art tries to focus on a set of specific themes, identified in some relevant studies, which may be linked to the main fields discussed above. These are:

 Studies that propose an integration of users in the design process, such as "User Centered Design" studies (UCD),  Studies that provide a characterization of emotions and subjectivity onto the definition of product, such as "Kansei / Affective Design" (KD),  Studies that provide an environmental consideration in the design process, or "Eco-design". As a consequence, the intersection of these three areas allows us to define some relevance levels ranging from 1 to n, as 1 is the closer to the objective. Indeed, the first level is reached once a study which combines the three fields is identified; the level 2 if an association between only two fields is found, and so on. It would be at level 3 if we focus only on key areas, and finally, at level 4 and if we are interested in other areas more or less divergent from the three initial themes. These studies may be of minor interest but would likely contain useful information otherwise. Figure 1 above shows a brief quantitative summary of the relative findings.

The result lets us state that no significant amount of elements were found regarding the crossed result, allowing us to show that there is a scientific gap, and this actual investigation is a valuable study that could serve as an innovative support for the research field.

FROM SUSTAINABILITY TO ECO-DESIGN

This second part introduces the general concepts of Ecodesign and Green Kansei. We propose to show the place of these key areas into a wider scale by emphasizing their interaction with global sustainability development.

Indeed, sustainability has gathered more and more interests over the past decades, regarding both the fields of industry and research. Sustainability is a global principle which covers multiple dimensions such as social, economical and environmental interests [START_REF] Zafarmand | An Analytical Study on Product Subjective Sustainability through Kansei Engineering Approach[END_REF]. The latter -the environmental issues -turn out to be more related than others, and thus more often associated with sustainability principles. By stating a brief history, politics were the first concerned with the environmental impact, followed by administration collectivities and some pro-environmental organizations, then lately expanded at a wider scale. Nowadays, embracing ecofriendly principles almost become a fashion practice among concerned stakeholders in many fields, as green concept turns out to be an interesting issue. Today, that global trend brought by ecological interests is taken into account into product design development, through the principle of the so well-known Eco-design, or design for environment.

Sustainable Green Kansei

Product design and Eco-design are closely related to the sustainability development, this relationship is mainly inclusive, as it is presented in the model of Tischner and Charter [START_REF] Tischner | How to do EcoDesign? A Guide for Environmentally and Economically Sound Design[END_REF], where they clearly describe the link between product design, Eco-design, sustainable design, and sustainable development. Elias explains how product design is linked to the global sustainability process [START_REF] Dekoninck | Eco-Design: The Evolution of Dishwasher Design and the Potential for a More User-Centered Approach[END_REF]. Eco-design objectives aim to minimize the impact of the product's life cycle on the environment, factoring energy consumption, carbon emission, materials, packaging and transport, chemical substances, potential toxicity, recyclability and durability through the product lifecycle.

Eco-design tools & methodologies

We stated that Eco-design methodologies aim to support the creation of products which are less harmful for the environment. In this way, designing with sustainable objectives turns out to be a great challenge for manufacturers, as it implies for designer to understand the whole life cycle of the product. Life Cycle Assessment (LCA) is the first tool that is commonly used for Eco-design, from raw materials extraction, manufacturing, packaging, distribution, product use to the final disposal. An efficient Eco-design method must take into account the environmental impact of each phase of the product lifecycle. In the same way, Environmental Effect Analysis (EEA) is used to identify the product eco-profile, by retrieving the relevant factors for the reduction of the environmental impact during all lifecycle stages. Current Eco-design methodologies propose guidelines in order to formalize the design requirements retrieved from EEA [START_REF] Bonvoisin | Design for energy efficiency : proposition of a guidelines-based tool[END_REF] [79].

Software such as "Eco-design Pilot" [START_REF]Ecodesign Pilot[END_REF][START_REF] Wimmer | ECODESIGN Pilot: Product Investigation, Learning and Optimization Tool for Sustainable Product Development[END_REF][START_REF] Wimmer | The Application of the ECODESIGN PILOT and Methodical Support for the Implementation of ECODESIGN in Products[END_REF] exists helping to assess the EEA on the product lifecycle.

Various interesting Eco-design methods are also available in the literature [START_REF] Lofthouse | Ecodesign tools for designers: defining the requirements[END_REF][START_REF] Lofthouse | What they really, really want: user centered research methods for design[END_REF]79,[START_REF] Telenko | A Compilation Of Design For Environment Principles And Guidelines[END_REF]. The use phase is also taken into consideration by some studies such as [START_REF] Bonvoisin | Design for energy efficiency : proposition of a guidelines-based tool[END_REF][START_REF] Luttropp | EcoDesign and The Ten Golden Rules: generic advice for merging environmental aspects into product development[END_REF]. In addition, talking about the specific use phase, introducing the user himself in Eco-design is the main interest of the next chapter.

INTRODUCING THE USER IN ECO-DESIGN

After giving an overview of Eco-design principles, we intend to see in this third part the possibilities for integrating users in its main concept.

In the first place, designing for the environment brings a strong enthusiasm among scientists in several research fields, whereas various methodologies and tools were implemented and validated through a predictive analysis of the whole product lifecycle. Life Cycle Assessment (LCA) runs from the extraction of raw materials to disposal of the product, passing through the manufacturing, distribution and use phasessee Figure 10 -, and helps us understand the environmental impact of a designed product. The use phase is the key specific element that drives our current work, and brings the basic assumption of our statement. Indeed, the use stage is an important step of the product lifecycle, as it provides a sizeable part of environmental impact. It appears that environmental performance in the use phase is interesting and difficult to assess, while the available indicators in terms of environmental performance are merely about product-related rates related to energy consumption or carbon dioxide rejection.

Moreover, impacts that occur during the use phase are often determined by analyzing user's behavior [START_REF] Bhamra | Sustainable use: changing consumer behaviour through product design[END_REF]. The behavior of the user dealing with products is interesting to evaluate and later change in favor of a more sustainable practice. Influencing the behavior of users is therefore a difficult task. However, designers have the tools to reduce the environmental impacts of the product use, and supporting changes in that user behavior towards more sustainable behaviors [START_REF] Bhamra | Sustainable use: changing consumer behaviour through product design[END_REF][START_REF] Elias | Assessing user behaviour for changes in the design of energy using domestic products[END_REF][START_REF] Wever | User-centred design for sustainable behaviour[END_REF][START_REF] Lockton | Making the user more efficient: design for sustainable behaviour[END_REF].

Mapping ecological user behavior

A green product is defined as a product which complies with the most interesting environmental issues throughout its life cycle [START_REF] Quarante | Eléments de design industriel[END_REF]. From a general point of view, the association of the product design with environmental awareness necessarily involves a consideration of human factors [START_REF] Sherwin | Design and sustainability -A discussion paper based on personal experience and observation[END_REF]. Product design for sustainable environment is a "human-centered." discipline. Following this statement, Eco-design and User-centered design can therefore be considered as closely related. Thus, in the category of specific design methods, we can cite Lilley's model, for example [START_REF] Lilley | Design for sustainable behaviour: strategies and perceptions[END_REF], in her approach "Design for Sustainable Behavior" in which she explores how design can be used to influence the behavior of users to shift towards more sustainable practices. She describes three strategies to change user behavior and evaluates their effectiveness, by using a part of design methodologies found from the literature and also by enriching them with results from the analysis of a case study. These three strategies are the main current approaches that may be considered throughout the scientific community as frameworks for a user-centered ecodesign methodology.  Eco-feedback / Eco-retroaction [38,54],  Behavior steering [START_REF] Akrich | The description of technical objects[END_REF][START_REF] Jelsma | Designing environmentally efficient services; a 'script' approach[END_REF],  Persuasive technologies [START_REF] Arroyo | Waterbot: exploring feedback and persuasive techniques at the Sink[END_REF][START_REF] Fogg | Persuasive technology; using computers to change what we think and do[END_REF].

Lilley's model was later reused, enriched and updated by other authors, for mapping the association of user behavior and environment [START_REF] Bhamra | Sustainable use: changing consumer behaviour through product design[END_REF]. It appears then that the user can be affected by the information presented to him and his behavior could be influenced in this case.

MODELING USERS IN USER CENTERED PRACTICES

In this fourth part, we will focus especially on user elicitation and make a general statement on the current principles for integrating and evaluating users in generic user centered design studies. We will talk about User Experience, and the importance of designing this experience using User Centered Design methodologies.

In addition, we will see why usability assessment tools are useful for conducting this evaluation.

However, remaining close to environmental considerations, we can assert that the application of Ecodesign strategies has significantly reduced the environmental impacts of the life cycle of the product [START_REF] Lewis | Design +environment[END_REF]. Moreover, in order to understand the use phase, it is essential to have information about the user in order to adapt the product to his/her characteristics and preferences. And by "the user", we mean both the physical user, with his cognitive and psychological patterns and also the context of use. Therefore, it is necessary to merge the whole environment of the user to define the use phase. Nevertheless, such investigation requires a complete understanding of the user-product interaction process. According to the field of User Centered Design or Human Centered Design, users have been taken into account in the design process for years. Users may also be involved in the early design process through the practice of Participatory Design [START_REF] Noro | Participatory ergonomics[END_REF].

These user centered studies point out the user's characteristics and let their needs to be expressed. The main advantage of relying on such methodologies is rather important, since these practices allow enhancing the usability performance of the product by matching the user's needs with product design parameters. Thus, defining the user leads to the User Modeling techniques (UM). User Modeling is an area that has been widely considered in the research community for the past forty years. Early User Modeling techniques commonly refer to the area of Computer Science, as it is known more precisely in the Information Science and Artificial Intelligence, and basically used to improve the user implication on Hypermedia and Adaptative Systems. Later evolutions concern extensive implications on Human-Computer Interaction, Interface Design and today more and more implemented in consumer product design. Various techniques are used in user modeling, such as heuristic-based formal evaluation, brainstorming, expert reviews in sociology or ergonomics, direct tests on physical or virtual prototypes, acceptability surveys, interviews, observations, participatory design, task analysis, focus group, scenarios production and application, experience through ecological-economical paper, and ethnographic approaches [START_REF] Bouchard | User kansei Modelling and Ecodesign, Communication in GCMM[END_REF].

Designing the User Experience

From this point of view, products are perceived as perfect if they give the most suitable user experience. In order to reach that objective, two major steps are necessary. The first step is to assess a correct elicitation of the target user through User Modeling (UM), and the second is to design the suitable experience through the interaction of this user with the product, also referred as Experience Design (XD). Following this statement, Experience Design (XD) and User Modeling (UM) are considered as user-centered studies, as they may be linked with the field of User Centered Design (UCD)

User Centered Design overview

Centered Design (UCD) is a multidisciplinary design practice based on the active involvement of users. The UCD is considered the key to ensuring maximum usability of the product. The aim of this approach is then to improve the understanding of use and task requirements, thus ensuring the optimization of iterative phases between design and evaluation. To help justify its importance, the UCD approach is formalized in the International Standard Organization (ISO), making it a useful tool for any user-focused approach [3]. In practical terms, UCD is currently applied in industrial firms of all sizes, and stimulates technological development through the early inclusion of end users [START_REF] Mao | The state of user-centered design practice[END_REF]. The integration of the user in the design process has taken a while be mature [START_REF] Maguire | Methods to support human-centred design[END_REF][START_REF] Steen | Early user involvement in research and design projectsreview of methods and practices[END_REF]. Some authors demonstrate that this practice may also become an important factor of innovation [START_REF] Riaz | User-Driven Innovation at local companies[END_REF]. The user himself is not the only entity role in user-centered design, the

Meet requirements?

Plan the humancentered process

Understand and specify the context of use

Evaluate designs against requirements

Specify the user and organizational

Product design solutions

context of use is an important step in the analysis that has been taken into account. Various studies demonstrate the importance of this vision [START_REF] Shackel | Usability -Context, framework, definition, design and evaluation[END_REF][START_REF] Wever | User-centred design for sustainable behaviour[END_REF].

Usability assessment as a validation tool

Dealing with the analysis of use phase leads us to consider usability assessment methodologies. This step helps us define usability goals and validate the potential user-friendliness of any product concept. Usability tests that are conducted throughout product development to guide the design are called formative. These tests focus on identifying the strengths and weaknesses of the product and contribute to their iterative improvement. In contrast, tests that are conducted at the end of product development are called [START_REF] Dumas | Usability Assessment Methods[END_REF]. Usability is often defined as "the degree to which a product can be used by specified users to achieve defined objectives with effectiveness, efficiency and satisfaction in a specified context of use". Effectiveness is defined as "the accuracy and completeness with which users are able to achieve specific goals", efficiency as "the provision of resources expended in relation to the accuracy and completeness with which users will have achieved the objectives ", and satisfaction as "comfort in use, and a positive attitude towards subjective interaction with the product" [2]. The usability of a product is evaluated by analyzing data collected by different methods. Dumas & Salzman drew up a list of comparative methods in describing the basics of the different techniques, their strengths and weaknesses, measuring their characteristics, their validity and reliability, and how they are applied to the development and evaluation of products [START_REF] Dumas | Usability Assessment Methods[END_REF]. The table 2 below summarizes briefly these methods.

Categories Principles

Usability testing

Usability testing is an empirical method for uncovering the strengths and weaknesses in the usability of a product or system and, less commonly, for measuring or comparing its usability.

Usability inspections

The methods that emerged in the 1990s have moved in two directions: expert reviews, in which individual specialists inspect a user interface; and walkthroughs, in which small teams of developers led by a usability specialist use a group process to explore how tasks are performed.

Survey, Interviews & focus group

Traditionally, surveys have been used to reach large samples of users, interviews have been used to probe a small number of users more deeply, and focus groups have been used to stimulate users to express unique responses

Field methods

Field methods are a collection of techniques for studying users, their activities, and their interaction with products in real-world contexts. These methods are an important supplement to usability testing, heuristic evaluation, and surveys.

Table 2. Usability assessment methodologies [23].

Among the ideas put forth in the literature on evaluation of usability and affordance in design [START_REF] Nielsen | Usability inspection methods[END_REF]85], it appears that ethnographic methods are particularly suitable for considering environmental impact, regarding the quality of immersion that allows collecting real data and the in situ characteristic of the observation [START_REF] Dumas | Usability Assessment Methods[END_REF].

GREEN KANSEI FOR ECO-DESIGN

This fifth part summarizes these different visions of user and then introduces a further user definition by integrating Kansei-based factors or Eco-Kansei. The various fields we introduced in the previous chapter will serve as concrete support for its integration with the Kansei notions. That is the main innovative point that makes this assertion an interesting support for a multidisciplinary work.

About Kansei & Kansei Engineering

The importance of pointing out the subjective perceptions associated with the emotion was put forward by several scientists [START_REF] Green | Pleasure with Products, Beyond Usability[END_REF][START_REF] Norman | Emotional Design[END_REF]. Various techniques have emerged to take into account the integration of these features in the product design. Two major research streams about emotional approach exist with fairly similar views [START_REF] Bouchard | A European emotional investigation in the field of shoe design[END_REF].

 On the first hand, the concept of Kansei Engineering coming from Japan, initially developed by Mitsuo Nagamachi proposes to measure the subjective values associated with the products and translate them into product attributes [START_REF] Nagamachi | Kansei Engineering: A new ergonomic consumer-oriented technology for product development[END_REF][START_REF] Bouchard | Development of a KANSEI ENGINEERING SYSTEM for Industrial design[END_REF][START_REF] Schütte | Concepts, methods and tools in Kansei engineering[END_REF][START_REF] Mantelet | Prise en compte de la perception émotionnelle des consommateurs au sein du processus de conception de produits innovants[END_REF][START_REF] Dahlgaard | Kansei / affective engineering design[END_REF],  On the other hand, there is an European approach called "Emotional Design" used by authors such as Norman or Overbeeke [START_REF] Overbeeke | First Conference on Design and Emotion[END_REF][START_REF] Green | Pleasure with Products, Beyond Usability[END_REF][START_REF] Norman | Emotional Design[END_REF][START_REF] Schifferstein | Designing consumer-product attachment[END_REF] that would be rather associated with Experience Design, and the creation of feelings of attachment to the product.

Thus, Kansei Engineering measures emotional needs and translates them into design elements, in order to provide end-users with greater satisfaction and product acceptance. The transcription of the subjective characteristics experienced by the user (Kansei) towards perfect design elements remains one of the main challenges of emotional design [START_REF] Overbeeke | First Conference on Design and Emotion[END_REF]. Various methods to measure subjective emotions exist from statistics-based methods to those based on neural networks [START_REF] Chu | Initiative of Service and Product Design Based on Kansei Engineering -Construction of Design Methodology to Keep and Improve Product Value[END_REF]22]. There are many examples of affective dimensions considered in the literature, especially related to usability considerations which are relevant for our work because they directly affect user behavior. Examples are found in electronics [START_REF] Lin | Consumer-oriented product form design based on fuzzy logic: A case study of mobile phones[END_REF], computer interfaces [START_REF] Kim | Designing towards emotional usability in customer interfaces-trustworthiness of cyberbanking system interfaces[END_REF], and food products [START_REF] King | Development of a to measure consumer emotions associated with foods[END_REF]. It is also shown that errors or "faux pas" occur when product use leads to negative emotional responses and thus to a loss of usability [START_REF] Tsao | A study on embarrassment associated with product use[END_REF]. Furthermore, Han proposes to model emotional response with respect to product usability [START_REF] Han | Evaluation of product usability: development and validation of usability dimensions and design elements based on empirical models[END_REF]. His study provides a systematic approach for improving the emotional responses (objective and subjective) of consumer electronics. His approach can be used in the design and evaluation phase of the development process. It can help designers and developers identify critical design elements, diagnose usability problems, and predict the level of usability of consumer electronic products. The approach developed in this study is also applicable to other consumer products (such as appliances, automotive, communication devices, and so on), subject to minor changes. Usability is often defined along two main dimensions: a dimension in terms of performance objective and a subjective dimension related to the image or impression aroused. Subsequently, these subjective dimensions of usability may be easily linked to intangible Kansei factors, and satisfy our methodology principle.

Eco-Kansei

Green Kansei can be introduced as a central topic in our work. Indeed, we believe users' environmental awareness is closely related to the subjective notions usually covered by Kansei.

Both concrete and abstract Kansei factors may be taken into account through Eco-design, as they help linking ecological-awareness values and/or provoked emotions to product attributes. For example, concrete (or tangible) factors which are related to product parameters such as green color, forms associated with natural elements, light materials or texture may be related to environmental awareness. Abstract (or intangible) factors could also be set as parameters for understanding the user (user's terminal values, life experience, emotion associated with a particular content, opinions, culture [START_REF] Hofstede | Hofstede's culture dimensions[END_REF][START_REF] Hofstede | Geert Hofstede Cultural Dimensions[END_REF][START_REF] Hofstede | Geert Hofstede CULTURES AND ORGANIZATIONS[END_REF][START_REF] Reinecke | MOCCA -A System That Learns and Recommends Visual Preferences Based on Cultural Similarity[END_REF], moods and semantics surrounding the product [START_REF] Rokeach | The Nature of Human Values[END_REF][START_REF] Osgood | The Nature and Measurement of the Meaning, Semantic Differential Technique, A Sourcebook[END_REF]66].

We could sum up these elements into the term of eco-X, as we talk about eco-Kansei factors regarding the Kansei factors for environment, such as eco-values, eco-moods, eco-culture, eco-emotions, and so on.

These elements are useful to assess a complete understanding of users and their relationship with environmental issues. They help design user profiles or personas that will fit perfectly with the usability goals related to the environment. These elements will be useful as well for completing an UCD process.

Towards an Eco-User profile

In order to profile the user, we will introduce here what is known about persona. A persona is user profile that allows designers to highlight the objectives of the individual during the use of an artifact. This is an archetypal representation of actual or potential users of the product, which aims to highlight the behavior patterns of users, their goals and motivations, with a fictional description [START_REF] Blomkvist | Personaan overview of Personae and goal-directed design[END_REF].

Personas can focus on the user and the context of use with their fictitious characteristics [START_REF] Grudin | Personae, participatory design and product development: An infrastructure for engagement[END_REF][START_REF] Holtzblatt | Personae and Contextual Design[END_REF]. The integration of personas has many advantages in product design [START_REF] Miaskiewicz | Personae and usercentered design: How can personae benefit product design processes[END_REF], particularly on understanding the needs of the user but also the communication between designers. Several features should be considered for the identification of user profiles represented by a persona [START_REF] Kujala | Identifying and selecting users for user-centered design[END_REF], in this case, these features are detailed below: The creation of the personas should be based on established real data [START_REF] Goodwin | Getting from research to personas: Harnessing the power of data[END_REF][START_REF] Pruitt | Personas: Practice and theory[END_REF][START_REF] Olsen | Persona creation and usage toolkit[END_REF], which can be collected directly from users, or through more indirect sources [START_REF] Brangier | Persona: A Method to Produce Representations Focused on Consumers' Needs[END_REF]. Indeed, various market research surveys exist, regarding environmental behaviors. They could be useful for pointing out the segmentation of users and creating personas [START_REF]A framework for pro-environmental behaviours[END_REF][START_REF] Tns | TNS Global Study "The Green Life" Reveals Spectrum of Environmental Attitudes Across United States and the World[END_REF].

Scenario analysis

Analyzing the use phase must not be seen as a static process. User behaviors evolve while performing any task. Thus, we introduce scenario analysis in order to assess this dynamic evolution in the use phase. In fact, personas and scenarios are closely related. In other words, it would be interesting to focus on scenarios as they share on the face of the attributes and similar principles with the personas. Scenarios are stories. These are stories about people and their activities [START_REF] Carroll | Five reasons for scenario-based design[END_REF]. However, the literature emphasizes that the combination of scenarios and personae would be more convincing because the scenarios are less effective when their construction is not associated with personae [START_REF] Grudin | Personae, participatory design and product development: An infrastructure for engagement[END_REF][START_REF] Navarro | L'utilisation du scénario dans le processus d'innovation : Une lecture pluridisciplinaire[END_REF].

From values to product attributes

The Means-End Chain (MEC) theory in Marketing research could highlight the links between the identified values and product attributes, through a simple meansend chain. A means-end chain is a simple knowledge structure containing interconnected meanings through which product attributes are seen as means-to-ends or personal values [START_REF] Baker | Product attributes and personal values : a review of means-end-theory and consumer behaviour[END_REF][START_REF] Florence | Introduction à l'analyse des chaînages cognitifs[END_REF]. The product's attributes, consequences and values (ACV) and, above all, the links consumers establish between them, constitute the essence of the MEC [START_REF] Costa | An overview of means-end theory : potential application in food product design[END_REF].

TOWARDS A MODEL PROPOSAL

In this final part, we will conclude by proposing a new theoretical model as an initial framework attempting to merge the processes of Kansei Design, User Centered Design and Eco-design. This model is created according to the previous statements of each part discussed in the article.

By describing the state of the art, we noticed that few studies attempted to merge Kansei and Eco-design. Indeed, the various proposed approaches found in the literature [START_REF] Levy | Interdisciplinary Design Method for EcoDesign : Introducing Kansei research for design to EcoDesign[END_REF][START_REF] Chu | Initiative of Service and Product Design Based on Kansei Engineering -Construction of Design Methodology to Keep and Improve Product Value[END_REF][START_REF] Chen | A Kansei Engineering Approach to Eco-product Form Design[END_REF] are a source of interesting ideas, but the diversity of applications does not confirm their relevance to global methods of eco-design. The impacts identified are still focused on one single phase of the life cycle and does not take into account effects on other cycles. From a methodological point of view, an interesting view of the first has been already advanced and allowed the integration of Kansei, by considering Experience Design and methods of Eco-design, and then taking into account human values, semantics, functions and affordance [START_REF] Bouchard | User kansei Modelling and Ecodesign, Communication in GCMM[END_REF].

In order to settle ideas about our model, we will consider these various statements, following the literature review:

Standard Design model is used as a first support of the methodology : Pahl & Beitz [START_REF] Pahl | Engineering Design[END_REF] or Ulrich & Eppinger [85] Eco-design principles come as a layer above standard design, and integrates tools such as LCA and EEA [START_REF]Ergonomic requirements for office work with visual display terminals (VDTs) --Part 11: Guidance on usability[END_REF][START_REF] Bonvoisin | Design for energy efficiency : proposition of a guidelines-based tool[END_REF][START_REF] Lofthouse | Ecodesign tools for designers: defining the requirements[END_REF][START_REF] Lofthouse | What they really, really want: user centered research methods for design[END_REF]79,[START_REF] Telenko | A Compilation Of Design For Environment Principles And Guidelines[END_REF], actual user centered design principles are also presented as another layer [START_REF] Akrich | The description of technical objects[END_REF][START_REF] Arroyo | Waterbot: exploring feedback and persuasive techniques at the Sink[END_REF][START_REF] Fogg | Persuasive technology; using computers to change what we think and do[END_REF]38,[START_REF] Jelsma | Designing environmentally efficient services; a 'script' approach[END_REF][START_REF] Mccalley | Making energy feedback work[END_REF] Specific User-Centered Design methodologies include 4 basic phases: Analysis including field works, user definition and Kansei Engineering, Design Implementation and Deployment.

MEC theory [START_REF] Florence | Introduction à l'analyse des chaînages cognitifs[END_REF][START_REF] Baker | Product attributes and personal values : a review of means-end-theory and consumer behaviour[END_REF][START_REF] Costa | An overview of means-end theory : potential application in food product design[END_REF] from the marketing research is a tool for translating the values to product attributes and comes across the Analysis and Design phase.

Eco-Kansei factors, user experience, usability, affordance and values perception come as an iterative group data that makes the link between the Standard Design method and UCD Methodologies.

Table 4. Theoretical assumptions of the new model.

Following these assumptions, we can propose on Figure 9 below a theoretical framework model which integrates the various point of views presented in this article. A major assumption in our research is that Kansei studies could expand our vision of user modeling for Eco-design by introducing advanced concepts in the subjective definition of users, and by building new user models encompassing complex dimensions such as ecovalues and eco-moods. We focused here on studies that take into account the subjective perceptions of users of the products in design, with a particular interest in the notions of value and semantics towards the environment, as we believe Kansei studies are actually of a great interest for Eco-design. With regard to this, we introduced the notion of Eco-Kansei to define Kansei factors which are relevant for environmental awareness. Eco-Kansei may be associated with common User Centered Design techniques on its analysis phase, and clearly enriches the definition of end-user profiles or personas. Other Kansei factors are still implemented, then usability testing are conducted towards the development process to ensure that the solution fits with the user's usability profile.

Building a framework linking Kansei Design, User Centered Design and Eco-design is the main issue of this paper. According to a literature review, a new user model was proposed, which integrates the three key fields: Eco-design, User Centred Design and Kansei. This theoretical model is only set into a macro vision in order to let each area be further improved into more specific procedures, as protocols and task analysis will be applied in experimental context after selecting an industrial product to validate its effectiveness. To this end, the formalization of an applicable methodology of EcoUCD is the next step of this work. Besides, the long term objective of our work could be met by generating a concept of User Centered Design model with a particular attention to environmental interests, pushing obviously the research towards another level of consideration. That makes this window an interesting prospect for future applications of Kansei studies.

Figure 1 .

 1 Figure 1. Key fields distribution among 147 references.

Figure 2 .

 2 Figure 2. Eco-design and sustainable development (Adapted from Tischner et al. [81] in [21])

Figure 3 .

 3 Figure 3. The product lifecycle [10]

Figure 4 .

 4 Figure 4. Example of standard vacuum cleaner eco-profile [25]

Figure 5 .

 5 Figure 5. Three strategies for designing sustainable behaviour [46]

Figure 6 .

 6 Figure 6. Key human-centered design activities (from ISO 13407)

Figure 7 .

 7 Figure 7. User Centered Design Process including context of use [72,88]

Figure 8 .

 8 Figure 8. Mapping model in affective design [40].

Figure 9 .

 9 Figure 9. Proposed basic framework for a User-Centered Eco-design methodology.

Table 1 . Difference between EuP and Erp [91]

 1 Today, further inclusion should be considered aiming towards an ecological implication for Kansei. In fact, Kansei design must be regarded as the integration of the subjective evaluation of Kansei factors into sustainable design. Mapping the Kansei design would lead to the enrichment of Tischner and Charter's model. As shown in Figure2above, this inclusion allows us to introduce the ecological part of Kansei through the notion of "Green Kansei".

	Eco-design is defined by the International Standard
	Organization as the integration of environment aspects
	into product design and development ISO/TR 14062 [1].
	Another definition of Eco-design comes from the
	European Union. In fact, according to Directive
	2005/32/EC for Energy products [27], Eco-design means
	the integration of environmental aspects into product
	design in order to improve environmental performance
	of the EuP throughout its whole life cycle.
	Two directives related to Eco-design have been adopted
	by the European Union: Directive 2005/32/EC [27] and
	Directive 2009/125/EC [28]. The first directive regulates
	energy-using products (EuP) while the second is its
	replacement and regulates energy-related products
	(ErP). The difference between EuP and Erp is related in
	the table 1 below [91].
	Energy-using Products	Energy-related Products
	 require energy (electricity,	 impact energy consumption
	fossil fuels or renewable	during their use;
	energy) input to work as intended;  includes products that	 examples include construction materials such as windows & insulation and
	generate, transfer or measure	water-using products such as
	energy;	shower heads & tap;
	 excludes products that	 includes EuP;
	transport people or goods.	 excludes products that
		transport people or goods.

Table 3 . Persona characteristics [43].

 3

ACKNOWLEDGMENTS

The authors are grateful to the French National Research Agency for funding this project, and express their gratitude to all partners of the ECO-USE consortium for their collaboration.