1 Copyright © 2008 by ASME

Proceedings of IDETC/CIE 2008 ASME 2008 International Design Engineering Technical Conferences &

Computers and Information in Engineering Conference August 3-6, 2008, New York, New York, USA

DETC2008/49651

A COMPILATION OF DESIGN FOR ENVIRONMENT PRINCIPLES AND GUIDELINES

Cassandra Telenko Department of Mechanical

Engineering, Cockrell School of Engineering, The University of

Texas at Austin

Carolyn C. Seepersad Department of Mechanical

Engineering, Cockrell School of Engineering, The University of

Texas at Austin

Michael E. Webber Department of Mechanical

Engineering, Cockrell School of Engineering, The University of

Texas at Austin ABSTRACT

Public policy is becoming increasingly stringent with respect to the environmental impacts of modern products. To respond to this tightened scrutiny, product designers must innovate to lower the environmental footprints of their concepts. Design for Environment (DfE) is a field of product design methodology that includes tools, methods and principles to help designers reduce environmental impact. The most powerful and well-known tool within DfE is Life-Cycle Analysis (LCA); however, LCA requires a fully specified design and thus is a retrospective design tool, only applicable as the end of the design process. Because the decisions with the greatest environmental impact are made during earlier design stages, it is important to develop concurrent design tools that can implement DfE principles at conceptual and embodiment design stages, thereby achieving more substantial environmental improvements. The goal of this work is to compile a set of DfE principles that are useful during the design process; explain select principles through examples; and provide an example of applying DfE principles concurrently during the design process.

1. INTRODUCTION Environmental factors are receiving heightened attention in product development activities. Over the past decade many tools have been developed to guide designers towards making more environmentally sound decisions. Many of these tools can be classified broadly into two categories: life cycle assessments and principles and guidelines for DfE.

Life-cycle analysis (LCA) is a standard quantitative tool defined by the ISO 14040 series for analyzing the environmental impacts of a product during all stages of its life cycle [1]. A complete life cycle incorporates stages from

extraction of raw materials, to production processes, to product usage, to end-of-life recycling or disposal of the product and its constituents. For each stage, the LCA accounts for inputs, such as raw materials and energy, and outputs such as air, land, and water emissions and other by-products. When all of the life cycle stages are evaluated in this way, it is difficult to inadvertently transfer harmful environmental impacts from one stage to another (e.g., from production to raw material extraction.)

With its quantitative, life-cycle perspective, designers find LCA useful for assessing the impacts of product development decisions on resource depletion, human health, and environmental degradation. However, designers also recognize that a comprehensive LCA requires significant amounts of time and highly detailed data describing the final product [2; 3]. For example, LCA requires complete information on the mass of each type of material in the final product, and precise quantities of material and energy inputs and outputs of each stage of the production process. This information is typically available only in the final stages of product development, after most product design decisions have been made.

As shown in Figures 1 and 2, decisions made in the conceptual and embodiment stages of design determine a significant portion of a product's environmental impact, but LCA cannot be utilized until the design is fully defined in the detailed phase of design or later. Accordingly, LCA is most appropriately a retrospective design tool that is primarily helpful for making last-minute design changes, modifying bills of materials, or designing a variant of an existing product. Designers require a concurrent design tool, such as DfE principles, that can be applied during the conceptual and embodiment design phases preceding LCA.

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LCA

• Requirements List

Task Clarification

• Requirements List

Task Clarification

• Preliminary Layout• Definitive Layout

Embodiment Design• Preliminary Layout• Definitive Layout

Embodiment Design

• Preliminary Layout• Production, Assembly Instructions

Detailed Design• Preliminary Layout

• Production, Assembly Instructions

Detailed Design

• Concept (Principle Solution)

Conceptual Design

• Concept (Principle Solution)

Conceptual Design

Disassembled Parts• Landfilled/Recycled Parts

RetirementDisassembled Parts

• Landfilled/Recycled Parts

Retirement

• Upgrades• Part Replacement

Servicing• Upgrades

• Part Replacement

Servicing

• Final Product

Production

• Final Product

Production

DfE

Prin

cipl

es a

nd G

uide

lines

Figure 1: The Product Development Stages, Showing LCA as a

Retrospective Tool and DFE as a Concurrent Design Tool [4]

Figure 2: Environmental 'Lock-In' Over a Product's Development Cycle [5]

DfE principles and guidelines have been developed to guide designers in creating product concepts and layouts when lack of time and detailed information prohibit a full

LCA. Examples of guidelines include “ensuring rapid warm up and power down for energy efficiency” and “ensuring easy access to fasteners and joints for disassembly and recycling.” DfE principles often reflect lessons learned from LCA that pinpoint flaws or potential improvements in candidate designs for improved environmental impact. DfE principles and guidelines also promote consistency and systematization between design processes, facilitate communication of new discoveries, and provide an important set of environmental solutions to complement or replace unavailable LCA data [6].

The difficulty with DfE principles and guidelines is that they are scattered throughout the literature, in various forms and levels of abstraction, and often with focused emphases on specific life-cycle stages, products, or industries. A comprehensive set of DfE principles is needed that synthesizes best practices from across these various sources and organizes them in a form that is immediately useful to designers in a broad range of industries. In this paper, our primary objective is to compile and present such a set of principles. Before we present the set in Section 4, we describe our research approach in Section 3 and the literature from which we construct our set in Section 2.

2. EXISTING DESIGN FOR ENVIRONMENT PRINCIPLES

The goal of this research is to establish a comprehensive set of DfE principles that designers, from a variety of industries can use immediately to reduce the environmental impact of designs throughout their life cycles. Published lists of DfE principles and guidelines typically fall short of this goal in one or more ways, including level of abstraction, focus on individual life-cycle stages, and specificity to certain products, industries, or stakeholders.

Many published lists of DfE principles focus on a single life-cycle stage, often in the form of Design for X strategies [5-9]. Examples include Design for Disassembly, Design for Recycling, and Design for Energy Efficiency. End-of-life strategies, such as recycling and disassembly, are relatively well established in the literature while principles for energy efficiency are still being developed. Because these types of principles and guidelines have been developed and published separately, the risk is that the designer may focus on a few simple strategies and lose the holistic, life-cycle perspective provided by a more comprehensive set of principles.

Many industries and companies have developed their own sets of specific guidelines, rules, and checklists [10-12]. Volvo, for example, instituted a Black, Grey, and White list of prohibited, cautionary, and clean materials in the late 80s/early 1990s [13]. Philips has a general list of EcoDesign guidelines, though they are difficult to procure [14; 15]. Likewise, Siemens created its own list of 40 principles [16]. As an example, Hewlett Packard’s mobile products follow specific rules for electronic display, such as, “Set display brightness to lowest comfort level to conserve energy / battery life [17].” Because the rule is solution-specific, it confines the designer to a specific technology, such as electronic displays, rather than alternative, innovative solutions such as organic

3 Copyright © 2008 by ASME

displays that reflect ambient light. If the principle were more general and applicable to a broader range of products, it would encourage designers to utilize a component with best-in-class energy efficiency and reevaluate or redesign the solution for each design cycle. This example illustrates the difficulty with industry- or product-specific guidelines and shows that principles may be more useful if they apply to a range of products.

Similarly, many regulations are being developed for products in specific regions and industries. The Restriction of Hazardous Substances (ROHS) and Waste Electrical and Electronic Equipment (WEEE) directives are two widely accepted sets of rules for prohibited materials in electronics [18]. The European Eco-Label [19] provides a few product specific guidelines and requires a full life-cycle assessment. The McDonough Braungart Design Chemistry Certification [20] offers a checklist point system to certify different levels of products, most of which are in the material and chemical domains. While these are useful requirements for a designer to meet, they do not provide guidance that sets of DfE principles offer in realizing new, environmentally friendly concepts.

In contrast to the industry- and product-specific sets of guidelines, some sets of DfE principles are extremely abstract. These lists typically articulate high-level goals of creating ecologically beneficial products. Anastas et al. [21] and Braungart [22] and McDonough et al. [23] provide lists of abstract principles, such as “it is better to prevent waste than to treat or clean up waste after it is formed.” Luttrop et al. [24] created a list of ten generic principles which bring DfE to an intermediate level from which each product designer derives a set of specialized guidelines. Although these lists cover the entire scope of Figure 1, they do not provide actionable guidelines for improving a product and inspiring innovation.

Finally, many DfE strategies are focused on managers or manufacturing process specialists, rather than product designers. Over 100 guidelines have been established for combining DfE for product, packaging, process and management with a focus on how DfE strategies work in cooperation across companies [5; 7-9; 25]. Referring back to Figure 1, these lists extend DfE guidelines to include everything from corporate attitude to the housekeeping of processing plants. To emphasize the holism of DFE, many guidelines within these lists begin to stray from an emphasis on the product designer. While companies should assume an environmental management system (EMS) and designers should acquire knowledge of production processes and supply chains [26], the purpose of this literature review is to create a set of principles geared towards a designer. For example, a designer does not need a principle for good housekeeping during production, (e.g.,minimizing waste and reusing waste streams) but a guideline as to how good housekeeping is facilitated by the design of the product (e.g. environmental Design for Manufacturing and material specification.)

While general principles, DfX guidelines, and product specific checklists do exist, designers are left to sift through

these sources to create their own version of DfE. There is no consolidated set of principles that can be used by the general product designer. In the following section, we present our methodology for creating such a comprehensive set of principles from these sources.

3. METHODOLOGY FOR COMPILING A SET OF PRINCIPLES Our research began by compiling the principles, guidelines, and checklists described in the previous section. To merge the various types and levels of statements into a comprehensive set of principles and guidelines, we organized and synthesized them into comprehensive categories and hierarchical levels of abstraction using a mindmap [27]. During the mindmapping process, we reformulated each principle to meet four criteria. The criteria are defined as follows:

o Designer-oriented: the principle must be within the scope of a product designer

o Actionable: the principle must propose an avenue for improving the design

o General: the principle must apply to a large range of products

o Positive Imperative: the principle must focus on creating the best solution possible

In this section, we describe the four criteria in greater detail and then summarize the overall methodology for establishing the comprehensive set of principles.

The designer-oriented criterion defines the audience for this set of principles and guidelines. It requires that each principle be formulated to direct designers, rather than managers or other stakeholders. When reformulating principles to be more designer-oriented, we found it helpful to refer to Pahl and Beitz’s [4] list of the types of decisions typically made by a product designer: 1) overall layout, 2) form and types of components, 3) selection of materials, and 4) communication with the user or manufacturer.

The actionable criterion requires that high-level goals, such as “Ensure long life,” be broken into potential avenues for achieving the goal, such as “Ensure that aesthetic life meets technical life” and “Plan for efficiency improvements.” The purpose is to ensure that designers are left with not just high-level aspirations, but useful tips for improving a product. In the final set of principles, we present both principles (goals) and guidelines (avenues). Accordingly, designers are motivated by the abstract goal of “ensure long life,” for example, and simultaneously presented with corresponding guidelines that suggest specific design avenues.

The general criterion requires that principles apply to a variety of product categories and design problems. For example, adjectives such as “ozone-depleting” and “carbon-creating” were combined under the broader category of “hazardous.” Directions for using natural materials, or not using synthetic or non-ferrous metals, were generalized to terms such as renewable, recyclable, and low-embodied

4 Copyright © 2008 by ASME

energy. As an example of an industry-specific rule, furniture designers are encouraged to specify sustainably-forested wood [5; 11]. This rule was subsumed under the more general guideline, “Specifying renewable materials.”

Using the positive imperative form helps focus the designer on positive possibilities, including what to use rather than what not to use. Many current design guidelines are of the form: “Do not…” or “Avoid… toxic or hazardous substances [8].” “Specifying non-hazardous and otherwise environmentally “clean” substances, especially in regards to user health” [5; 7-9; 25; 28-32] is only a slight modification of the guideline, but places immediate focus on finding new solutions rather than old problems.

These criteria were applied in the context of a mind-mapping process [31] for categorizing and synthesizing the principles gathered from the literature. A mind map is a visual recording of a brainstorming session. The center of a mind map contains the overall function or goal of the brainstorming session. Ideas and possible solutions are drawn from the center and grouped into sets of similar concepts. For the purposes of this research, “Design for Environment” was placed as the overall objective at the center of the mindmap, and principles, guidelines, and rules fulfilling this objective

were placed as sub-branches. Principles were the level directly stemming from DfE. Guidelines stemmed from unique principles and rules stemmed from guidelines. Figure 3 presents a portion of the final mind map as an example. The use of a mind-map allowed us to identify interdependencies and overlapping principles, arrange the principles in hierarchical levels of abstraction, and ensure similar levels of specificity across the mindmap.

The mind-map originally resulted in four levels of principles branching from the DfE center. The first level contained principles. The second level contained either further sub-principles or guidelines. The third level contained either rules stemming from guidelines or guidelines stemming from sub-principles. The lowest level consisted of product specific rules, which were abstracted to general guidelines as previously discussed. Overlapping principles and sub-principles were reformulated into a single, combined principle. Equivalent guidelines were combined into one encompassing guideline, and all principles and guidelines were reviewed to meet the four criteria: designer-oriented, actionable, general, and positive imperative. The methodology resulted in 6 principles and 67 guidelines.

Design for Environment

Minimize Resource

Consumption in Production and Transport

Phases

Minimize Resource

Consumption in the Use Phase

Specifying Lightweight

Materials and Components

Employing folding,

nesting or disassembly

Minimizing the number of components

Specifying clean, efficient manufacturing

processes

Specifying materials that don’t require

inks or surface treatment

Incorporating part-load

operation and allowing users to turn off systems in part or whole

Specifying best-in-class

energy components

Interconnecting available flows of

energy and materials within the product and its environment

Implementing reusable

supplies and ensuring maximum usefulness

Incorporating intuitive

controls for energy saving

functions

Incorporating features which prevent waste of materials by

the userApplying structural

techniques and materials

Ensure sustainability of resources

Enable disassembly, separation,

and purification

Ensure healthy inputs and outputs

Increase durability of the product

and components

Design for Environment

Minimize Resource

Consumption in Production and Transport

Phases

Minimize Resource

Consumption in the Use Phase

Specifying Lightweight

Materials and Components

Employing folding,

nesting or disassembly

Minimizing the number of components

Specifying clean, efficient manufacturing

processes

Specifying materials that don’t require

inks or surface treatment

Incorporating part-load

operation and allowing users to turn off systems in part or whole

Specifying best-in-class

energy components

Interconnecting available flows of

energy and materials within the product and its environment

Implementing reusable

supplies and ensuring maximum usefulness

Incorporating intuitive

controls for energy saving

functions

Incorporating features which prevent waste of materials by

the userApplying structural

techniques and materials

Ensure sustainability of resources

Enable disassembly, separation,

and purification

Ensure healthy inputs and outputs

Increase durability of the product

and components

Figure 3: Final DfE Mind Map (abridged)

5 Copyright © 2008 by ASME

Table 1: Principle A - Sustainable Resources

Principle A. Ensure sustainability of resources by: [5; 9; 21] 1. Specifying renewable and abundant resources [4; 5; 7; 8; 25] 2. Specifying recyclable, or recycled materials, especially those within the company or for which a market exists or needs

to be stimulated [5-9; 16; 25; 28-32] 3. Layering recycled and virgin material where virgin material is necessary [7; 25] 4. Exploiting unique properties of recycled materials [7; 25] 5. Employing common and remanufactured components across models [6-8; 16; 31; 32] 6. Specifying mutually compatible materials and fasteners for recycling [4; 6-8; 16; 25; 28-32] 7. Specifying one type of material for the product and its subassemblies [6; 7; 9; 16; 24; 25; 28; 30-33] 8. Specifying non-composite, non-blended materials and no alloys [6; 24; 25] 9. Specifying renewable forms of energy [5; 6]

4. DESIGN FOR ENVIRONMENT PRINCIPLES This section presents the full compilation of principles

and guidelines, with select product examples. The principles are re-conceptualized from the mind map and literature review to fit the criteria and begin with A and B for resource selection, C for production and transportation, D for use, E for extended life and F for disassembly. Examples are used to demonstrate how principles may be applied and also how they overlap and work together. The principles are rooted in the literature (Section 2), but the consolidation of principles from disparate sources, the hierarchical arrangement into principles and guidelines, and the wording of each principle and guideline are distinctive to this work.

4.1 Principle A: Ensure Sustainability of Resources Table 1 lists guidelines for fulfilling principle A, “Ensure

sustainability of resources by….” Principle A aims to address resource depletion by encouraging reuse of resources within the technosphere, such as materials and components, and renewability of consumed resources, such as energy. The guidelines apply to every aspect of the product, including consumables and packaging.

Guideline A-4: Exploiting unique properties of recycled materials.

Guideline A-4 from Table 1 reminds designers to fully utilize the qualities of recycled materials. Treatment of materials, such as forming and pigmenting, adds extra and potentially harmful processing steps. However, by making use of unique textures, color combinations, and intermixed patterns of recycled material, a designer can realize untapped potential, forgo additional production steps, and divert valuable material from landfills.

A great example of not just recycled, but reused material comes from Bitters Company. They design doormats and key-chains using foam rubber salvaged from the excess of Flip Flop production. Re-using waste from the manufacturing stage, Bitters Company maintains the original coloring to

create patterns in their final doormat or key-chain. Figure 4 shows the clever use of the rubber foam for a floating keychain [34].

Figure 4: Bitters Company Uses the Original Coloring and other Properties of Flip Flop Scraps to Make Products such as

Floating Key-Chains and Doormats [34]

Document Centre 220

Newly Manufactured

Document Centre 220

Re-Manufactured

Document Centre 440

Conversion - New Model

Document Centre 220

Newly Manufactured

Document Centre 220

Re-Manufactured

Document Centre 440

Conversion - New Model

Figure 5: Xerox® Uses Remanufactured Modules [35]

Guideline A-5: Employing common and remanufactured components across models.

Guideline A-5 is an expansion upon the utility of guideline A-2 (Specifying recyclable materials…) There is no need to design for recyclability, durability, or reuse if the parts are not reused or become outdated. By using common parts

6 Copyright © 2008 by ASME

and remanufactured components, a designer ensures that those parts complete their useful lifetimes and avoids the unnecessary materials and manufacturing associated with additional virgin components. The designer may also create a product line that supports reuse by enabling interchangeable parts.

One example of designing with remanufactured components comes from the redesign of the Rank-Xerox® photocopiers in the 1990s [31]. Designers overhauled the structure and modularity of their photocopiers to accommodate remanufactured modules, from current and previously introduced products. One can see from Figure 5 that the Document Centre™ 440 only makes additions and a few component replacements to the previous Document Centre™ 220 model. Each model contains remanufactured parts, such as paper trays, and common cartridges [36].

4.2 Principle B: Ensure Healthy Inputs and Outputs Table 2 lists guidelines for fulfilling principle B, “Ensure

healthy inputs and outputs by….” Healthy inputs and outputs are those that do no cause environmental degradation or adversely affect human health. This principle requires elimination of hazardous substances and pollutants as well as the conversion of waste to useful materials for products and ecosystems. Like principle A, principle B applies to every aspect of the product, including consumables and packaging.

Guideline B-13: Specifying the cleanest source of energy.

Guideline B-13 focuses on emissions from energy sources. Often, a product’s largest environmental impact will

be dependent upon the type of energy specified during use. By using clean energy sources, such as solar and wind power, a product can avoid power plant effects. This guideline also includes a rule usually cited as “use rechargeable batteries” rather than disposable batteries. Thus, a product will result in the disposal of one set of batteries, and not dozens, thereby reducing toxic waste at end-of-life.

The Seiko Kinetic® Auto Relay, shown in Figure 6 exhibits both aspects of this principle; it has no batteries and no external chargers. Seiko’s watch is powered by the kinetic energy of the wearer’s movement, a readily available and clean energy source. The watch is charged after a few side to side motions, and operated by an automatic power generator [37]. An additional power saving feature is that hand motion stops after the watch is stationary for 72 hours. The watch maintains the correct time internally for up to 4 years of inaction. Within those four years, the watch can be shaken to return to the correct time [38].

Figure 6: Kinetic Energy Powers the Seiko Kinetic® Auto Relay[38]

Table 2: Principle B - Cleaner Resources

Principle B. Ensure healthy inputs and outputs by: [21; 24] 10. Installing protection against release of pollutants and hazardous substances [7; 25] 11. Specifying non-hazardous and otherwise environmentally “clean” substances, especially in regards to user health [5; 7-

9; 25; 28-32] 12. Ensuring that wastes are water-based or biodegradable[5; 6; 16; 30] 13. Specifying the cleanest source of energy [5; 7; 25; 31] 14. Including labels and instructions for safe handling of toxic materials [7-9; 29-33] 15. Specifying clean production processes for the product and in selection of components [7; 16; 29; 30] 16. Concentrating toxic elements for easy removal and treatment [7; 24; 25; 29; 30; 33]

Table 3: Principle C - Production and Transport

Principle C. Ensure minimal use of resources in production and transportation phases by: [24; 32] 17. Replacing the functions and appeals of packaging through the product’s design [7; 25] 18. Employing folding, nesting or disassembly to distribute products in a compact state [7; 25] 19. Applying structural techniques and materials to minimize the total volume of material [4-9; 16; 24; 25; 28-30; 32] 20. Specifying lightweight materials and components [6; 8; 16; 25] 21. Specifying materials that do not require additional surface treatment or inks [5; 7; 25] 22. Structuring the product to avoid rejects and minimize material waste in production [4; 7; 16; 25] 23. Minimizing the number of components [7; 16; 25; 31] 24. Specifying materials with low-intensity production and agriculture [8; 25] 25. Specifying clean, high-efficiency production processes [5; 8; 16; 25; 30] 26. Employing as few manufacturing steps as possible [30]

7 Copyright © 2008 by ASME

4.3 Principle C: Ensure Minimal Use of Resources in Production and Transportation Phases

Table 3 lists guidelines for fulfilling principle C, “Ensure minimum use of resources in production and transportation phases….” Principle C encourages the designer to think about how product attributes affect the efficiencies of seemingly unrelated processes. Guidelines for fulfilling principle C, shown in Table 3, provide direction in structuring and sizing products to reduce material waste in production and reduce the load and number of shipments to lower fuel use and emissions

Guideline C-19: Applying structural techniques and materials to minimize the total volume of material.

Guideline C-19 challenges the designer to find alternatives to over-dimensioning a product. The emphasis lies in rethinking over-dimensioned and “one size fits all” [21] solutions. Rather than increasing thickness or size, one should try to specify lightweight and high strength materials as well as investigate sturdier and more compact geometries. Figure 7 shows the Black and Decker® Leaf Hog™ which

uses ribbing to achieve not only structural rigidity but also internal part placements. Additionally, the creation of thinner walls aids the injection molding process. Thin walls aid in cooling, and reduce shrinking, overall improving the efficiency of resources in manufacturing.

Figure 7: The Black and Decker® Leaf Hog™ Uses a Ribbed

Structure to Increase Strength and Reduce Material Use

Table 4: Principle D - Use Phase

Principle D. Ensure efficiency of resources during use by: [5; 9; 21] 27. Implementing reusable supplies or ensuring the maximum usefulness of consumables [5; 7; 10; 16; 25] 28. Implementing fail safes against heat and material loss [7; 10; 25; 29; 31] 29. Minimizing the volume, area and weight of parts and materials to which energy is transferred [7; 10; 25; 31] 30. Specifying best-in-class, energy efficient components [7; 8; 10; 25; 29; 31] 31. Implementing default power down for subsystems that are not in use [5; 7; 25; 31] 32. Ensuring rapid warm up and power down [10] 33. Maximizing system efficiency for an entire range of usage conditions [9; 10; 25] 34. Interconnecting available flows of energy and materials within the product and between the product and its

environment [9; 21] 35. Incorporating partial operation and permitting users to turn off systems partially or completely [7; 9; 25; 31] 36. Using feedback mechanisms to indicate how much energy or water is being consumed [5; 8] 37. Incorporating intuitive controls for resource-saving features [8; 10] 38. Incorporating features that prevent waste of materials by the user [7; 25] 39. Defaulting mechanisms to automatically reset the product to its most efficient setting [7]

4.4 Principle D: Ensure Minimal Use of Resources during Use

Table 4 lists guidelines for fulfilling principle D, “Ensure minimum use of resources during use by….” Principle D motivates the product’s design to be efficient in its consumption of energy and material and its interactions with the user during the usage stage of its life cycle.

Guideline D-38: Incorporating features that prevent waste of materials by the user.

Guideline D-38 requires designers to be more conscious of how their product will be used or misused, and what aspects of material use can be guided by design. A few examples of this guideline are found in products that use calibration marks for a user to measure the correct amount of water, washing powder, or coffee they place into their product [7; 25]. Another instance of how products can be designed to

aid the user is the incorporation of funnels to prevent spillage [7; 25].

Figure 8: The ECO kettle™ Responds to User Habits and

Helps Users Heat Only What They Need [39]

8 Copyright © 2008 by ASME

A good example of this guideline is the ECO kettle™. Electric kettles already provide insulation and direction of heat (D-28) through the use of an enclosed heating coil.

However, the ECO kettle™ accounts for a common mistake of water-heating consumers – heating too much water. Combining D-29 (minimizing the volume of heated areas) and D-38, the designers partitioned the kettle into separate storage and heating compartments, which have gradients measuring the contents by cup volume. Most importantly, this allows the user to continue their habit of leaving extra water in the kettle (not wanting to refill the kettle every time they heat water) but also begin a habit of heating the correct amount of water. Thus, energy is saved, and environmentally responsible habits are encouraged.

Guideline D-34: Interconnecting available flows of energy and materials within the product and between the product and its environment.

Guideline D-34 exhibits a core principle of sustainability--imitating nature by making use of nearby resources, waste material and energy. Some famous and broader applications of this principle are solar power and regenerative braking. Solar power makes use of the prime source of energy available to the planet, but requires the designer to be mindful of product exposure to sunlight. Regenerative braking recovers expended energy. Instead of braking a car by disk or drum brakes and losing kinetic energy as heat, the electric

generator is reversed from powering the wheels to being powered by, and effectively slowing, the wheels.

Retrofit products, such as the SinkPositive in Figure 9, are now being marketed to the environmentally conscious consumer. One flush of a toilet sends one gallon or more of potable water down the drain. Washing one’s hands after using the toilet causes additional loss of this increasingly important commodity. SinkPositive combines the two interlinked functions by connecting a sink to your toilet tank. After a user flushes the toilet, replacement water is fed through an added faucet, providing water to the patron at just the right moment and reducing water use relative to a bathroom with a separate toilet and sink.

Figure 9: SinkPositive Diverts Tank Water Through a Faucet[40]

Table 5: Principle E - Durability

Principle E. Ensure appropriate durability of the product and components by: [5; 16; 21; 24; 29] 40. Reutilizing high-embedded energy components [21] 41. Planning for on-going efficiency improvements [9; 29] 42. Improving aesthetics and functionality to ensure the aesthetic life is equal to the technical life [5; 7; 25; 29; 30] 43. Ensuring minimal maintenance and minimizing failure modes in the product and its components [6-9; 30; 32] 44. Specifying better materials, surface treatments, or structural arrangements to protect products from dirt, corrosion, and

wear [4; 24] 45. Indicating on the product which parts are to be cleaned/maintained in a specific way [7; 25] 46. Making wear detectable [4; 7; 25] 47. Allowing easy repair and upgrading, especially for components that experience rapid change [4; 24] 48. Requiring few service and inspection tools [4] 49. Facilitating testing of components [4] 50. Allowing for repetitive dis- and re- assembly [4]

4.5 Principle E: Ensure Appropriate Durability of the Product and Components

Table 5 lists guidelines fulfilling principle E, “Ensure appropriate durability of the product and components by….” Extending the life of a product avoids extra transportation and processing steps, as well as postponing waste, recycling, and remanufacturing steps. Principle E addresses this aspect by presenting two important strategies: durability for long life, coupled with the ability to update the product to current best practices. In this way, use of old, inefficient technology is not prolonged. Since the durable product can be updated in parts,

designers have time to develop new, innovative, environmental solutions and/or incorporate the latest environmentally friendly technology.

Guideline E-47: Allowing easy repair and upgrading, especially for components that experience rapid change.

Guideline E-47 tries to avoid a waste problem that many consumers experience: a product contains many components and features; one of those becomes obsolete or breaks down; and the consumer is forced to purchase an entirely new product. This situation is not only irritating to consumers, but creates an unnecessary amount of waste, rendering operational components useless. Evidence of this

9 Copyright © 2008 by ASME

phenomenon is most apparent in the electronics industry, where cell phones are replaced yearly.

A model for this principle is the highly modifiable desktop computer. Every tower has standard slots and sizes for DVD ROMs, CD ROMs, and video cards. Mother boards come with the same slots, with options to upgrade and change memory types. Whole computers can be built at home from spare parts – saving assembly energy, reducing waste of old parts, and allowing upgrades to more energy efficient components.

4.6 Principle F: Enable Disassembly, Separation, and Purification

Table 6 lists guidelines fulfilling principle F, “Enable disassembly, separation and purification by….” Recycling, remanufacturing, reuse, repair, and, upgrading can be facilitated by incorporating these features for disassembly, separation, and purification. These features are often found as structural solutions complementing principles A-E. For this reason, an example for principle F will be shown that also aids principle E.

Guideline F-59: Organizing a product or system into hierarchical modules by aesthetic, repair and end-of-life protocol; and Guideline E-42: Improving aesthetics and functionality to ensure the aesthetic life is equal to the technical life.

Guidelines E-42 and F-59 facilitate the longevity of an initial design in the hands of a user. A physically durable component or product is useless if a consumer replaces it before it becomes obsolete. Created with a “classic” or updateable design, a product can stand the test of time in usefulness and appeal to the consumer.

The fulfillment of these guidelines is shown by Ford’s Model U Concept Car from 2003. Figure 10 shows the interior of Ford’s design using modular structures and common components for aesthetics. The interior is “uncluttered” to allow consumers to modify the interior as they choose. Upholstery, slots and electronic connections are arranged so the user can insert and remove both electronics and finishings. It is a long-term, upgradeable investment, designed to accommodate changing preferences and needs [41]. The design includes both recyclable and biodegradable materials. The Ford Model U’s architecture helps a user customize the base, the floor, and the fabric. Modules that are removed during the use and upgrade of the vehicle are designed to be easily accessible and standardized. At end-of-life, materials are organized into recyclable and biodegradable waste.

Figure 10: Ford Model U Concept Car has a Modular and Upgradeable Interior [37]

Table 6: Principle F - Disassembly

Principle F. Enable disassembly, separation, and purification by: [21] 51. Indicating on the product how it should be opened and make access points obvious [5; 7; 25; 28; 31] 52. Ensuring that joints and fasteners are easily accessible [28; 31; 32] 53. Maintaining stability and part placement during disassembly [4; 31] 54. Minimizing the number and variety of joining elements [7; 16; 24; 28; 31-33] 55. Ensuring that destructive disassembly techniques do not harm people or reusable components [4; 31; 32] 56. Ensuring reusable parts can be cleaned easily and without damage [4] 57. Ensuring that incompatible materials are easily separated [6-8; 31; 32] 58. Making component interfaces simple and reversibly separable [6-8; 25; 31-33] 59. Organizing a product or system into hierarchical modules by aesthetic, repair, and end-of-life protocol [4-8; 16; 25; 28;

29; 31; 32] 60. Implementing reusable/swappable platforms, modules, and components [4; 6; 8; 29-32] 61. Condensing into a minimal number of parts [5-9; 30-32] 62. Specifying compatible adhesives, labels, surface coatings, pigments, etc. which do not interfere with cleaning [5-8; 16;

25; 28; 31-33] 63. Employing one disassembly direction without reorientation [7; 16; 25; 31] 64. Specifying all joints so that they are separable by hand or only a few, simple tools [7; 16; 25; 31; 32] 65. Minimizing the number and length of operations for detachment [16; 31] 66. Marking materials in molds with types and reutilization protocols [4; 5; 8; 9; 16; 25; 28; 30; 31; 33] 67. Using a shallow or open structure for easy access to subassemblies [7]

10 Copyright © 2008 by ASME

5. AN EXAMPLE APPLICATION OF THE DFE PRINCIPLES DURING CONCEPTUAL AND EMBODIMENT DESIGN

The Nostalgia Electrics™ “Old Fashioned Cotton Candy Maker”, shown in Figure 11, is used here as an example application of the DfE principles as a concurrent design tool for conceptual and embodiment design.

Sugar goes inside Spindle

Hot webs spun out holes

Motor drives spindle shaft

Resistive Heating Coils

Fan to force convective heat

flow

Spindle heats and melts sugar

Figure 11: Nostalgia Electrics™ “Old Fashioned Cotton Candy

Maker”

Cotton candy machines typically consist of a motor, a heating element, a spindle, a bowl and a cone. The Nostalgia Electrics configuration for these parts is shown in Figure 11. The cotton candy is made by melting sugar in the spindle. The spindle is rotated at a high speed so that melted sugar is spun out by centrifugal force through very tiny holes in the spindle sides. As the liquid sugar passes through these holes, it becomes aerated in the ambient temperature and solidifies into thin, fluffy cotton candy strands that can be collected by a cone.

We illustrate how six guidelines can be used to design a new home cotton candy machine. The goal for the new design is to reduce the environmental imprint of the product without relying explicitly on life cycle analysis. In the remainder of this section, four redesigns are offered by applying DfE principles in the pre-LCA stages of conceptual and embodiment design (Figure 1).

5.1 Conceptual Design If a designer were familiar with guideline D-34 (Ensure

efficiency of resources during use by interconnecting available flows of energy and materials within the product or between the product and its environment), he or she would begin the design process looking for synergies between the product and available resources in a typical consumer’s home. One possibility is the capability of a common, household blender to rotate blades at a high velocity--a shared capability with the cotton candy maker. A designer may then create a home cotton candy maker, not as an independent home appliance, but as a modular accessory that connects to a generic blender.

Figure 12: Cotton Candy Accessory for a Blender [42]

A concept is shown in Figure 12, from U.S. Patent #4,501,538. The design includes an attachable bowl for containing the sugar webs and an attachable heating fixture and spindle component. This concept also follows guideline C-23 (Ensure minimum use of resources in production and transportation phases by minimizing the number of components) by eliminating the need for an excess motor and base unit. The synergistic, blender-accessory concept reduces the environmental and monetary costs of production by reducing the number of necessary components, materials, and manufacturing processes.

5.2 Embodiment Design In the embodiment stage, three additional guidelines can

be applied to improve the spindle design. The first guideline is D-29 (Minimizing the volume, area, and/or weight of parts and materials to which energy is transferred.) The cotton candy accessory concept in Figure 12 combines the heating element with the spindle, requiring that the motor rotate both components. To reduce the amount of energy needed to rotate the spindle, the spindle and heating element can be separated. These modifications are shown in Figure 13.

Remove heating element from spindle

Insert bearing for independent movement

Heating Element as Base

Drive shaft couple to Blender

Remove heating element from spindle

Insert bearing for independent movement

Heating Element as Base

Drive shaft couple to Blender

Figure 13: Modifications to Separate the Heating Element and

Spindle [42]

11 Copyright © 2008 by ASME

As shown, the heating system is moved from the top of the spindle to the bottom, around the drive shaft. A bearing is inserted to separate the base heating element from the spindle and allow relative motion. The motor is thus relieved of a significant portion of the prior component’s weight, and the entire device requires less energy to operate.

The same guideline can be applied to the heating coils of the original design (Figure 11). Figure 14 shows the current, oversized heating coil on the left, and two alternative embodiments on the right.

Spindle Outline

Coils Below

Original Shortened Arced

Figure 14: Two Parametric Solutions to Improve Heating Efficiency

Portions of the heating coil in the original design leave clear pathways for waste of heat. If the coils were shortened or converted to arcs, they would heat only the minimal area of the spindle, rather than overcompensating. Lastly, two additional guidelines can be applied to reduce water use during cleaning of the device. Although sugar is easily dissolved and washed away, nine customer interviews with the Nostalgia Electrics™ “Old Fashioned Cotton Candy Maker” showed that users would waste water while spending minutes continually running water to clean the spindle of leftover sugar. A disassembled spindle could be wiped clean in a matter of seconds. Figure 15 shows that the spindle has a cover connected by a rivet.

Rivet

Figure 15: Spindle with Rivets and Sugar Caught Inside

By specifying this joint as a removable fastener, such as a wing nut, the designers would enable a very quick rinse of the device. These changes are motivated by three guidelines: F-56 (Enabling disassembly, separation and purification by

ensuring reusable parts can be cleaned easily and without damage), F-64 (Enabling disassembly, separation and purification by specifying all joints so that they are separable by hand or only a few, simple tools), and D-38 (Ensuring efficiency of resources during use by incorporating features that prevent waste of materials by the user).

By applying six key guidelines to the design of an improved cotton candy maker, we have eliminated the need for a motor and associated materials in production and disposal and enabled more efficient energy and water use during the product’s useful life.

6. CLOSURE A total of 6 principles and 67 guidelines have been

compiled and illustrated with examples. By drawing from current best practices within the literature, this compiled list maintains the lessons of the past decade. Application of the three criteria of generality, designer orientation, and action-ability ensures usefulness of the guidelines for product designers across multiple domains and life-cycle stages. The fourth criterion–the positive imperative—focuses a designer on making positive and specific innovations, rather than correcting previous mistakes. Hierarchical organization of the set into principles and guidelines further distinguishes the goals of DfE (principles) from actionable suggestions for achieving those goals (guidelines). As exhibited by the examples, these principles and guidelines are formulated to be used concurrently during conceptual and embodiment design.

There are several opportunities for further work. For example, conflicts between guidelines could be addressed in a more transparent and quantifiable way. Brezet et al. [25] present a table of the conflicts and complements between eco-design principles and other design considerations (e.g safety and cost). It would be useful to study these conflicts and devise solution principles for resolving them. One readily available example is the conflict between enabling repair and upgrading and eliminating the need for replacements with a more durable innovation. A solution to this conflict could involve modular upgradeability, as in the example of modern computers.

As evidenced by the plethora of published guidelines, principles, and checklists, DfE principles are still being discovered. Further work is needed to expand the list as new principles become available and to incorporate discoveries from other domains such as building architecture. Finally, the list of principles and guidelines is based on best practices, as reported in the literature, but rigorous, quantitative validation of many of these principles is still lacking.

ACKNOWLEDGMENTS We gratefully acknowledge support from the University

of Texas at Austin and members of the Webber Energy Group, and the Product, Process, and Materials Design Lab at the University of Texas at Austin

12 Copyright © 2008 by ASME

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13 Copyright © 2008 by ASME

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