Volume 2, Number 1, Fall 2001

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A Heuristic Approach to Ecodesign

H. Randolph Holt, P.E.
Associate Professor
Department of Technology
Northern Kentucky University
Highland Hts., KY 41099-0839

Abstract

Design doesn’t begin with the designer in most companies.  Typically, it starts with marketing and customers in the form of a set of design requirements, is expanded by technical management and systems designers, and is then given to a team of designers for detailed analysis and implementation.  Ideally, this process is a cyclical one that requires several iterations before reaching consensus.  A number of non-environmental issues and constraints are part of that dialog, all being critical to the success of that design in the marketplace.  Environmental issues must conform to the overall goals because they can radically affect such design factors as performance, cost, reliability, size, weight, product market timing, manufacturing processes, interfacing, safety, testability, and a host of other issues that every designer has to consider during the design process.

Introduction

Recognizing that the key step toward an environmentally-friendly product occurs during the actual design process, a number of researchers and organizations have concentrated on ways to incorporate environmental principles into design methodology.  Called ecodesign, design for the environment, design for recyclability, and sustainable design, these approaches concentrate on ways to measure resource and energy requirements during the manufacturing of that product, during its operational life, and at its disposal .  “Outputs” of toxic liquids and gases are also monitored during the life cycle of a product to assess the damage they can do to the environment.

The most popular methodology appears to be life cycle assessment (LCA).  This is primarily a chemical and energy prediction scheme that looks at all resource requirements and byproducts of manufacturing, operating, and disposing of the product and assists in determining where improvements can be made.  Generic products such as disposable diapers and cloth diapers seem to fit this approach, especially since it can then help people understand how to make decisions on which one is kinder to the environment over its entire life cycle.  The process is very complex, requiring extensive analysis to obtain the data.  Obviously, the more components and processes that a product has makes an LCA even more difficult.

Other methods have used matrices or formulas to determine a product’s impact on the environment.  This is also a difficult approach, primarily because of the large number of variables in a typical design.  Assumptions usually have to be made to simplify these variables down to a manageable few.

It’s possible that someday the actual design process may become more deterministic, but the synthesis required for a typical design requires that a large number of variables and approaches be considered before finally arriving at an acceptable approach.  It’s difficult to measure whether a given design approach is optimum, given that most product designs have a large number of acceptable solutions.  Besides considering the very large number of variables in a design, a measurement scheme would have to develop ways to assess importance to design variables that are not always black and white and often not directly measurable.

Until better tools arrive, perhaps the best approach would be to avoid the objective ones and concentrate on a more subjective scheme.  Combining it with collaboration and consensus by the product team might offer some insight into how to proceed in the future.

It is also important that any environmental design aspects be an integral part of the overall design process where the impact of its inclusion will be weighed against the other design issues.

A Typical Product Design Cycle

Most designers start with a basic document from marketing and customers that describes in general terms what is to be produced.  The name of this document will vary depending on the organization, but many companies refer to it as a requirements document.  Even though there may be some design details in it, most people recognize that its purpose is not to constrain the designer but instead gives broad strokes and direction to the design process while also satisfying the customers.

In this early stage, the designer reviews this requirements document and gradually adds details that describe how the design will proceed.  This is called a specifications document in some organizations and grows in detail as the design proceeds.  A series of design reviews are normally scheduled to coincide with milestones in the design process, and this specifications document is expanded at those reviews.  Since most designers today use some sort of a hierarchical approach to avoid getting lost in details, the specification will gradually expand as the work proceeds down into the hierarchical inverted tree.

Agreement on the requirements and specifications between marketing, customers, management, and the technical contributors is critical throughout the design since any missed communications can result in wasted effort and/or a product that is not appropriate.  A team approach is preferred to make sure all issues are discussed fully, and it’s critical that management avoid any heavy-handed dictates unless there is no alternative.

Typical Design Constraints

The requirements document provides the designer with information on what the product is to do and the limitations on that design.  Some of these constraints may have flexibility, permitting the designer some latitude.  Others may be “yes-no” constraints that cannot be adjusted.  Some of these fixed constraints could relate to product safety (UL or CSA certification) and conformance to interface standards (the product must have certain characteristics because it is to be connected to an existing device).

The type and number of constraints will vary with the product being designed.  Described in this section are some of the limitations found in most requirement documents.

This is perhaps the most important element in most designs – the product must perform at a level to make it competitive or superior in the marketplace.  The requirements document may state the desired performance above which the product must operate, so the designer often has some latitude in meeting this goal.  If the design fails to meet this objective, it is probably a failure.  Performance is also measurable, and the designer must be able to run tests to verify conformance to this requirement.  The requirements document must describe how performance is to be measured, and the designer must insist that this be included.

Simulation software is now available for most designs to verify performance and to verify performance over part tolerance variations, temperature changes, and input variable changes.  Some software packages even provide Monte Carlo statistical techniques to permit random statistical variations on component parameters in a system as a way of ensuring that the product will perform to specification within the tolerance bands of the components.

A second important variable in most designs is the cost of the product, not just the direct costs but also the indirect or overhead costs incurred by the corporation in making, shipping, advertising, repairing, supporting, and disposing of it.  Some products may have costs as a secondary consideration when performance is critical, but even for military products today costs are important.  Cost is also measurable for the designer, but the organization must supply overhead cost data or give the designer a “rule of thumb” to use.  The designer must understand that the methods and labor used to manufacture the products are critical; if changes in the manufacturing process are required to make the product, they can drastically affect the cost.

In most designs, reliability is also an important consideration.  The requirements document should specify it, normally expressed as a mean-time-between-failures (MTBF) in hours.  Reliability is a statistical value that can be calculated using reliability prediction software, and known values for specific components can be inserted if known.  Military and aerospace products are usually expected to provide these values, and a number of companies have implemented the MIL-HDBK-217 criteria into software that can make the calculations.  Two methods are used, part count and stress analysis.  Part count reliability simply permits the user to add up the various parts, subsystems, connections, etc., and obtain an MTBF based on those counts.  Stress analysis is a more complicated procedure that takes the operating environment and the electrical/electronic stress of each component into consideration and thus delivers what is considered to be a better result.

Another aspect of system reliability depends on how proven the design is.  A novel design has not been adequately observed, so designers must factor this into consideration and lower the reliability value for such unproven approaches.

A design must also result in a manufactured product that arrives in the marketplace at the proper time.  The marketing window is critical in today’s business world because of global competition and the exponentially-growing technology curve.  If the design requires additional time beyond that window, it may also result in a failed project.

Project management software tools are essential for today’s complex designs and can help avoid the problems associated with this type of constraint.  Their abilities to do “what if” analyses and resource reallocation while also serving as project status displays during design milestone meetings can help avoid any pitfalls with respect to project timing.

Most products require that they be safe for the user/consumer.  This is usually a “yes-no” type of constraint when being reviewed during design.  At all hierarchical levels, the safety of the product must be considered.  Many standards also address issues that impact the user of a product, including such concerns as heat, radiation, and emissions.  The specific safety standards for the product must be defined in the requirements document. 

The product must be designed to be manufactured using the processes available or the processes being planned for implementation before this product is turned over to manufacturing.  It is crucial that the designer intimately know the manufacturing processes and their limitations.  If a new process is required, the design team must take the proper steps to ensure that it is in place and verified before the design is produced.

These constraints are probably the newest addition to the requirements document for most designers.  Because governments and consumers are becoming increasingly concerned about a product’s impact on the environment, many companies are responding by making it a high priority.  The manufacturing process must be environmentally acceptable, the product must be both energy and resource efficient during its useful life, and provisions must be made for its disposal when no longer operational or useful.

Most designs are either improvements to existing designs or new designs that are only part of a total design.  They are typically electrically and mechanically connected to other subsystems or peripherals and need to conform to specific standards so they interface properly in the total system.  Any design changes that affect this interface can have far-reaching effects on the product and must be carefully considered by the total design team.

Weight and physical dimensions are often another constraint for the designer.  The designed product must meet market and operational size and weight constraints as defined by the consumers and marketing.  Ergonomic issues would be part of this constraint.

The product must be designed so that it can be tested and repaired, both during the manufacturing process and when found defective.  If possible, provisions can also be included to permit the end user to run tests on the product.

In some cases where the cost of repairing is too high to justify for the selling price of the product, the designer should consider methods of disposal.

In most of today’s products, a number of subsystems are often purchased from OEM suppliers rather than being designed from scratch.  Such things as power supplies, enclosures, displays, bearings, etc., are normally purchased and used as a part of the product.  It is important to consider what impact a design will have on these purchased items.

Many designs include embedded intelligence and some software and/or firmware that defines significant value added to the product.  The microcontroller or microprocessor might have limitations on memory size and input/output pins that the designer must consider during the design process.

A Design Worksheet Proposal

Rather than develop a methodology based on environmental issues, a better approach might be to make these issues an integral part of the total set of design constraints for that product.  As any design approach is being considered, it’s important that every design constraint be visited and thought given to how it will be affected by that design approach.

A worksheet can be developed to use as a communication tool with the team when new design approaches are being considered.  This worksheet can be initially filled in by the designer, but it’s crucial that the team review, alter, and expand the explanations, and reach consensus on the final draft.

All constraint areas defined by the team as a part of the requirements document must be considered.  For each area, a scale is proposed to identify the degree of impact on that area for the design approach being considered.  Check boxes could include:

 

$                       large negative impact

$                       moderate negative impact

$                       slight negative impact

$                       little or no impact

$                       slight positive impact

$                       moderate positive impact

$                       large positive impact

 

Each constraint category would also have a text area where the team enters an explanation and data for that decision.

If a hierarchical design approach is being used, this worksheet could be used to identify what the designer and the team suspect will occur within that abstract area when details are added at a lower hierarchical level.

Since many designs are based on existing designs, the worksheet might only be used in those areas where significant changes are being suggested.  For instance, in taking an existing design and adding environmental elements to conform to a standard, only those areas affected by the redesign would be considered.  Design areas using “standard” approaches might be excluded.  The design team can determine just where the worksheet would be applied.

The worksheet could look like this:

                                                                                               

 

 

 

 

 

 

 

 

 

Getting Ready for the Approach

Several key things need to occur before this type of heuristic approach can be applied.  Since it is based on teamwork and consensus, the organization must prepare for this type of design if such changes haven’t yet taken place.  Many companies have already organized this way because they have recognized that a design will only be successful if it includes input from all areas where the product will impact – engineering, marketing, manufacturing, purchasing, and service.

Some designers will also have problems with this type of approach.  Even though formal education is changing to recognize the importance of teams, many designers have been educated to be technical contributors who perform a large part of their jobs independently.

The environmental part of the design will probably be the one where additional training will be required, largely because it has not typically been included in the formal education and backgrounds of most of the team members.  It is important that the team be especially familiar with the manufacturing process and its impact on the environment.  They must also be kept aware of changes to that process that improve the environmental conditions and be encouraged to incorporate those concepts into new designs.

Deciding to include eco-labels like TCO’99 into the design will support this environmental constraint and supply some principles that must be followed if the product is to achieve certification; one place to obtain information on this European environmental standard is http://www.tcodevelopment.com .  Documents can be downloaded from that web site that describe the eco-label and what must be done to comply with it.  TCO’99 also includes some corporate items that extend beyond the design phase: the company must comply with a standard like ISO 14001 (they have an environmental management system in place), and they must team up with a recycler who will assist them in disposal of the product at its end-of-life stage.

Here is a list of some of the issues that a company must address for TCO’99 certification:

‘           ISO 14001 or EMAS environmental management system certification

‘           declared mercury content in LCD monitors

‘           one type of plastic for all parts weighing more than 100 g

‘           PVC is not to be used

‘           no painting of plastic parts

‘           no metallic coating of plastic parts

‘           agreement with a recycling company to establish a recycling scheme

‘           no cadmium in CRT monitor

‘           no ozone-depleting substances used to manufacture printed circuit boards

‘           no use of chlorinated solvents in printed circuit board manufacturing

‘           no mercury or cadmium in batteries or electronic components

‘           no flame retardants in plastic components weighing more than 25 g

‘           labeling of all plastic parts weighing more than 25 g in accordance with ISO

‘           no less than 2% recycled monitor glass in new CRT monitors

IBM and Apple have committed to environmental design, and both companies have made documents available on the Internet that can be used as a part of a heuristic design effort.

Apple has an environmental web site ( http://www.apple.com/about/environment  ) where one can obtain interesting articles and product information involving environmental design applications.

One paper (Fiksel & Cook, 1996) is available online at the Apple site and is a very good article on the application of DFE principles to the Power Macintosh 7200 personal computer system.  It describes the overall design process, the determination of the design attributes used, and includes a table highlighting the design decisions relating to those attributes.  According to the authors, the fundamental product requirements (cost, manufacturability, servicing, and performance) were not negatively affected by these environmental objectives.

IBM’s web site at http://www.pc.ibm.com/ww/healthycomputing/envreport contains information on their approach to DFE.  “Guiding Principles” for IBM’s DFE effort encourage design of products that can be upgraded, reused, recycled, safely disposed at end of life; recycled materials should be used when possible, and efforts should be taken in the design to improve energy efficiency and reduce energy usage in the product.

Another web page hyperlinked to the IBM site describes “15 Environmental Attributes” that are to be considered in IBM products.  Most of these are identical to those given in TCO’99 (above), but the attributes are more detailed and include an attribute regarding compliance of OEM product and subassembly producers to the IBM DFE practices.

To better describe the design process using “Environmentally Conscious Design,” IBM also provides a copy of corporate standard C-S 1-9700-020/1997-05 on their website at http://www.no.ibm.com/ibm/environment/97102524.pdf .This document is a more detailed account of IBM’s design practice that also lists materials that are not to be used in their products as well as materials that need to be identified.  This document can certainly serve as a starting point for companies that are in the process of developing their own environmental standards for design.

A Simple Example

A simple electronic product costing $150 is currently very popular in the United States, and the company is interested in marketing possibilities in Europe.  The design team has identified an oem-supplied ac adapter as one area to be investigated for redesign.  It currently is a linear supply that provides 9 volts and 300 mA to the system via a standard mini-plug

The designer responsible for this part of the redesign has determined that a switching mode ac adapter might be a better choice.  It is twice as efficient as the linear supply currently being used and has a calculated MTBF of one million hours versus fifty thousand hours.  Unfortunately, it is two to three times the cost and has a slightly larger case.  Even though the switching frequency could add noise to the system, this is not considered a factor because it is to be isolated from the electronics in a separate enclosure.  The switching mode supply can also accommodate both 50 Hz and 60 Hz power frequencies where the linear design would necessitate a different ac adapter for each frequency.

In preparation for a design review, the designer has completed the worksheet as shown below:

 

 

 

 

 

 

 

 

 

This information can now be used by the team to discuss the constraints and determine what action is to be taken.

Future Enhancements

Even a heuristic approach can be useful to designers.  Relying on team consensus, this technique can help focus on the design attributes that are important to a given product and highlight the areas where additional effort needs to be applied.

A step to further apply the technique would be to include this information within the design automation records.  A database could be developed with fields defined for the constraint values and explanations.  A numeric value could designate the current impact with positive values for improvements and negative values for negative impacts.  The magnitude could reflect the degree of change.  Each impact field would have an explanation field.  Each record could be linked to the associated design details for that particular design step.

Data could be collected with each phase of the design, enabling designers to observe the changes made during the design process.

Once enough data is collected, a knowledge base search engine could be used to enable designers to look at how specific problems were handled in other designs.  An expert system or other artificial intelligence software application could also be developed to use this data in assisting with future design efforts.

With collection of sufficient data, a more quantifiable approach could then be taken that might use weightings and actual values to more carefully monitor designs.  Given the number of variables considered in most design efforts, this might be difficult.  Because of the creative process and the inherent art of design, there is some speculation that such an approach might assist designers in considering alternative approaches but would still require human involvement.  Just because computers can generate artwork doesn’t mean that they will supplant the human artist.

Conclusions

When a large number of variables are found in a synthesis problem, such as for a new product design, a deterministic solution may be very difficult or impossible.  When these variables have specified values or limited ranges of values, and a large number of valid solutions may exist, it may be better to use a heuristic approach that provides a methodology for teams to interact and select the “best” design. 

Now that many designers are adding environmental variables to the standard design process, even more issues need to be considered and discussed.  Techniques such as LCA are being incorporated into some design approaches, but they are one-dimensional in that they concentrate on chemical and energy elements but don’t deal with many of the other design constraints that are an essential part of a new product.

References

Arnst, C. (2001, Spring).  The Art of Invention.  Business Week 50. Spring 2001.  pp. 204-206.

Carnegie Mellon University [Online].  Green Design Initiative.  Available:

http://www.ce.cmu.edu/GreenDesign/ [2001, March 20].

Fiksel, J. & Cook, C. (1996, May) [Online].  Design for Environment at Apple Computer:  A Case Study of the Power Macintosh 7200.  International Symposium on Electronics and the Environment.  New Jersey: IEEE Press.  Available:

http://www.apple.com/about/environment/design/case_study/powermac7200.html [2001, January 3].

Fischhoff, B., Lichtenstein, S., Slovic, P., Derby, S. L., Keeney, R. L. (1981). Acceptable Risk.  New York:  Cambridge University Press.

Holt, H. R.  (1992, April 10).  Engineering Ecodesign.  Proceedings of the 1992 North Central Section Spring Conference.  ASEE.

Holt, H. R.  (1994, May 3).  A First Step in Electronic Ecodesign.    International Symposium on Electronics and the Environment  (Publication # 94CH3386-9).  New Jersey: IEEE Press.

Kaplan, G. (1987, May).  On Good Design.  IEEE Spectrum.  May 1987.  pp. 27-72.

U. S. Environmental Protection Agency (EPA) [Online].  Design for the Environment.  Available:  http://www.epa.gov/opptintr/dfe/ [2001, March 20].