Problem Identification Approaches in Sustainable Design

Sustainable Design is the systematic application of environmental considerations to product design at all stages of a product's life cycle. These stages include resource extraction, manufacturing, shipping/transport, useful life, and end of life (from cradle to grave or cradle to cradle). The ultimate goal of Sustainable Product Design is to create systems that enable us to produce and consume goods and services without compromising our future. To achieve it requires a redesign of goods and services so that they are eco-efficient and/or eco-effective.

The essential aim of sustainable design is to produce places, products and services in a way that reduces use of non-renewable resources, minimizes environmental impact, and relates people with the natural environment. Sustainable design is often viewed as a necessary tool for achieving sustainability. It is related to the more heavy-industry-focused fields of industrial ecology and green chemistry, sharing tools such as life cycle assessment and life cycle energy analysis to judge the environmental impact or "greenness" of various design choice.

While the practical application varies among disciplines, some common principles are as follows:

-Low-impact materials: choose non-toxic, sustainably-produced or recycled materials which require little energy to process

-Energy efficiency: use manufacturing processes and produce products which require less energy

-Quality and durability: longer-lasting and better-functioning products will have to be replaced less frequently, reducing the impacts of producing replacements

-Design for reuse and recycling: "Products, processes, and systems should be designed for performance in a commercial 'afterlife'."

-Biomimicry: "redesigning industrial systems on biological lines ... enabling the constant reuse of materials in continuous closed cycles..."

-Service substitution: shifting the mode of consumption from personal ownership of products to provision of services which provide similar functions, e.g. from a private automobile to a carsharing service. Such a system promotes minimal resource use per unit of consumption (e.g., per trip driven).

-Standardization and modularity: standard, modular parts allow products to be repaired rather than replaced and promote interoperability so that systems can be upgraded incrementally rather than wholly scrapped and replaced.

Design engineers have a tough job, balancing safety, energy efficiency, and cost with the consumer's passion for the latest and greatest technology. Unfortunately, it seems that the design engineer rarely even gets to the point of thinking about what will happen to the product at the end of its useful life. At most manufacturing companies, the folks in the environmental department are usually concerned with the product's environmental impact, but they are primarily focused on the manufacturing operations and the operating life of that product. Good intentions aside, it seems that most folks don't give much thought to what happens to a product when it has reached the end of life. We have simply relied on the scrap recycling industry to deal with that problem and, up to now, recyclers have done a good job. However, as time goes by and new materials and technologies are developed, the challenge that recyclers face in safely and economically recycling those products grows ever more difficult. The issue becomes more and more vital and urgent.

To address these challenges, concept of Design for Recycling was created. to help protect the environment and create a sustainable means for conserving our resources. Design for Recycling seeks to achieve two very basic goals: first, to eliminate or reduce the use of hazardous or toxic materials that may present a grave danger to the environment or put a recycler's workforce in jeopardy, and second, to discourage the use of materials that are not recyclable or manufacturing techniques that make a product nonrecyclable using current technologies. The best time to address these issues is at the design stage. Addressing a product's end-of-life is essential at the very beginning. Adopting this premise helps to ensure a thriving recycling chain, which goes well beyond the scrap processor to the mill, smelter, or extruder who will take the recycled materials and make them into new steel, copper, brass, aluminum or plastics. Design for Recycling is a mindset that every design engineer must embrace if they hope to have their products considered environmentally friendly. The days of a manufacturing just concerning itself with the environmental impacts of its manufacturing process and its products during their useful lives are long gone – it is essential to design products having in mind their recycling.

Over the years, industry has faced significant challenges from materials such as cadmium, lead, to name a few. In each instance, we have worked diligently with the industry that has used these materials to seek alternatives that will still meet their needs and satisfy the customers' desires while still protecting the environment and workers involved in the recycling. There's more than environmental compliance at stake here. As new materials are developed, such as graphite composites, they pose a new threat to the recycling of products. As these new materials are introduced into products, displacing materials that have been recyclable for generations, they adversely affect the recyclability both practically and fiscally. Both can have a devastating impact. 

Even materials that are recyclable can pose a problem when used in combination. Take for instance a product that uses many different types of plastics. Today's recycling technology is such that it is very difficult to mechanically segregate more than two or three different types of plastic and hand sorting is simply not a cost effective means of accomplishing the job. A product that utilizes six, seven, or more polymers effectively becomes non-recyclable, or at least the plastics fraction of that product will be non-recyclable.

In sustainable design the concepts of Design for Reuse and Design for Disassembly go hand in hand with the Design for Recycling.

Recycling is the reprocessing of materials into new products. Recycling prevents useful material resources being wasted, reduces the consumption of raw materials and reduces energy usage, and hence greenhouse gas emissions, compared to virgin production.[1] Recycling is a key concept of modern waste management and is the third component of the waste hierarchy. Recyclable materials, also called "recyclables" or "recyclates", may originate from a wide range of sources including the home and industry. They include glass, paper, aluminium, iron, textiles and plastics. Biodegradable waste, such as food waste or garden waste, is also recyclable with the assistance of micro-organisms through composting or anaerobic digestion. Recyclates need to be sorted and separated into material types. Contamination of the recylates with other materials must be prevented to increase the recyclates value and facilitate easier reprocessing for the ultimate recycling facility.

TRIZ and TRIZplus can be effectively used for both for sustainable design problem identification and for problem solving. The essence of problem identification lies with determining so called eco-contradictions that is contradictions that derive from contradictory requirements of the Design for Reuse, Design for Recycling, Design for Disassembly etc. and the operational specifications for a product.

Typical requirements of the Design for Recycling, Design for Reuse and Design and Design for Disassembly, for example, are:

- remove subassemblies that can be resold as is.

- remove hazardous materials

- separate the remaining materials into single materials with as little effort as possible

- use modules (consolidated parts) that can be removed and reused in other applications

- mark all materials for identification that cannot be sorted easily

- make parts easy to disassemble

- reduce materials and energy invested in the parts

- reduce the number of parts

- reduce the part size

- reduce the time to assemble

- eliminate redundant components

- use recycled materials where possible

- reduce scrap

- evaluate materials chosen for their environmental impact, and recyclability

- minimize waste in production processes

- packaging should be eliminated, or replace with reusable packaging

- when reliability is a problem, make the components easy to maintain and repair.

- avoid finishing operations that might contaminate materials

- use snap fits that can be undone or broken easily

- mark the location of snap fits so that they can be separated quickly

- reduce the fastener count

- avoid threaded and permanent fasteners (eg glue)

- reduce the number of components to reduce the number of steps in disassembly

- assembly from top in layers so that parts can be picked off

- avoid parts with mixed materials

-etc.

The TRIZplus tools that can be effectively used for problem identification here are Function Analysis, Trimming and Function- Oriented Search.

Function Analysis and Eco-Contradictions Problems

Function Analysis is a primary tool for identifying eco-contradictions. The algorithm is rather simple:

1. Build a function model of a product/engineering system following the requirements of the operational specifications.

2. Build a function model of a product/engineering system following the requirements if the Design for Recycling, Reuse and Disassembly.

3. Juxtapose these function models.

4. Identify eco-contradictions.

Example. Filter bags for bag-houses for cleaning industrial gases should be durable: the non-woven fibers should be well entangled, the bad should withstand intensive abrasion against the supporting cage of the bags during the regeneration (especially in case of pulse jet cleaning). The fibers of the bags may have complex nomenclature – they may contain biodegradable threads and non-biodegdadable or even threads that may be toxic when deposited into a landfill.

At the same time, the requirements of the Design for recycling the bags should be:

-easy to disassemble – the fibers should be free from each other

-the toxic threads should be easily extracted and encapsulates (should be loose and free)

-the fibers should be weak and easy to break, etc.

Trimming and Trimming Eco-Problems

There is a number of requirements of the Design for Recycling, Reuse and Disassembly that appeal to Trimming directly. For example:

- reduce materials and energy invested in the parts

- reduce the fastener count

- reduce the number of components to reduce the number of steps in disassembly

- avoid finishing operations that might contaminate materials

- eliminate redundant components

- etc.

To identify eco-trimming problems:

1. Build a function model of a product/engineering system following the requirements of the operational specifications.

2. Perform Trimming according to the Design for Recycling, Reuse, Disassembly.

3. Identify Trimming Eco-Problems.

Function-Oriented Search and Eco-Substitution Problems

The environmental benefits of recycling are well known. Many businesses, governments, and households are collecting discards for recycling, and are recovering more materials than ever before. In fact, over one-fifth of the municipal solid waste generated in our country is currently recycled or composted. Despite progress in recycling, however, people are still generating too much waste. Every day, on average, each individual discards about four pounds of material. These discards burden both the environment and our economy.

Even recycling, which adds major economic and environmental benefits, creates economic and environmental costs. The best approach to our solid waste challenge is to cut the creation of waste in the first place. Waste that is not created does not have to be managed later. That's why waste prevention (reducing and reusing) is the ideal solid waste solution.

Waste prevention involves altering the design, manufacture and other life stages of a product towards either reducing the usage of the resources or at least substituting the expensive, toxic or hazardous materials with cheaper, environmentally benign and biodegradable substitutes.

As soon as the substitution gets into the picture Function-Oriented Search (FOS) can be effectively used for this purpose. Knowing what functions the undesirable components/materials perform a less harmful substitute can be found using a usual algorithm for using FOS.

Some comments on eco-problem solving. Because majority of contradiction can be successfully resolved by separating contradictory requirements in space, time, on conditions or system level as well as by satisfying them, a special role in problem solving belongs to so called smart materials.

Smart materials are materials that have one or more properties that can be significantly altered in a controlled fashion by external stimuli, such as stress, temperature, moisture, pH, electric or magnetic fields, etc. There are a number of types of smart material, some of which are already common. Some examples are as following:

-piezoelectric materials

-thermoresponsive materials, either shape memory alloys or shape memory polymers

-magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.

-pH-sensitive polymers

-halochromic materials

-chromogenic systems (electrochromic, thermochromic, magnetochromic, etc. materials)

-etc.

Conclusions

TRIZplus tools can be effectively used for problem identification in Sustainable Design for formulating

- Eco-Contradictions

- Eco-Trimming problems

- Eco-Substitution problems

with consecutive application of tools of classical TRIZ and Function-Oriented Search for problem solving.

References.

1. Fan Shu-Yang, Bill Freedman, and Raymond Cote (2004). "Principles and practice of ecological design". Environmental Reviews.

2. Ryan, Chris (2006). "Dematerializing Consumption through Service Substitution is a Design Challenge". Journal of Industrial Ecology. 4(1).

3. S.Ikovenko, K.Stevenson. TRIZ as a Tools for Sustainable Design and Environmental Engineering. Abstracts for TRIZCON 2005, April17-19, 2005, Brighton, MI, USA.

4. S.Litvin. New TRIZ-Based Tool – Function-Oriented Search. ETRIA Conference TRIZ Future 2004. November 2-5, 2004, Florence, Italy.

5. S.Litvin. TRIZ Readings – Altshuller’s Tradition Continues. ETRIA Conference TRIZ Future 2005. November 16-18, 2005, Graz, Austria.