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Sustainable Design

Ved Narayan on how CAE tools combine better product design with savvy business decisions for a positive environmental impact

Sustainable design is a comprehensive, holistic approach to creating products and systems that are environmentally benign, socially equitable, and economically viable: environmentally, such that the design offers obvious or measurable environmental benefits; socially, so that it fills the needs of everyone involved in its production, use and disposal or reuse; and economically, so that the design is competitive in the marketplace.

Fuel-efficient cars, solar-heated buildings, clean-burning power plants, recyclable packaging and low-voltage lighting are dramatic examples of products that help balance consumer needs with good environmental stewardship. Yet realistically, all products have the potential to be designed with sustainability in mind if engineers really think about making products better while using materials that positively affect the environment.

All products have the potential to be designed with sustainability in mind if engineers really think about making products better while using materials that positively affect the environment.

Implementing the practical aspects of sustainable design involves the following considerations:

• Minimal material use: Can you change the wall thickness of a part from half an inch to three-eighths of an inch without compromising its functionality? (e.g. housing for a wide-screen TV)
• Improved material choices: Is there a plastic that wasn’t available ten years ago, that would make this part easier to produce, recycle, or transport, for the same cost? (e.g. specify recyclable high-density polyethylene (HDPE) instead of acrylonitrile butadiene styrene (ABS))
• Design for ease of disassembly: Can the product be designed to be taken apart, either for repair or selective recycling? (e.g. use tabs to connect parts, rather than glue)
• Product reuse or recycling at end of life: Can the product be designed in a modular fashion, so that one part can be replaced to upgrade its function (e.g. rethink throwaway cell phones by selling a consumer-replaceable slide-in memory/function board)
• Minimal energy consumption: Is there a different method or machine for building or operating the system that uses less energy to run? (e.g. redesign oxygen-flow mask so it uses lower-pressure, less expensive pump-system at the consumer end)
• Manufacture without producing hazardous waste (e.g. the successful elimination of lead-based solder)
• Use of clean technologies as a fundamental mindset (e.g. hybrid automotive engines)

Why is a new way of thinking so economically important? The answer is that demand for natural resources is growing faster than the available supply, driving up their costs, at the same time that new environmental directives must also be met. Fortunately, small design changes—based on optimized amounts of carefully chosen, modern materials, manufactured with minimal energy or resource usage—generate large ripple-effects in the overall sustainable life-cycle, and offer the extra benefit of an improved competitive edge in the global market.

Consequently, companies that prioritize finding tangible, methodical ways to reduce material costs and improve processes will be leaders in maintaining profit margins.

A Lifecycle Approach to Product Design

Human nature believes that it’s easier to keep things as they are, even against persuasive arguments to the contrary. Often new products merely reflect a progression of incremental changes based on legacy designs and procedures. Think how a car is assembled: although robotics has played a huge role in the past few decades, the overall assembly process still follows the structure laid down by Henry Ford. Worse yet, steps such as gluing and welding have replaced screwing or bolting in many areas, such that subassemblies cannot be opened for repair, but must be trashed and completely replaced.

At the same time, traditional material costs are rushing upwards: the price index for non-manufactured goods rose from less than 70 (representing the actual price when compared to an average value set to 100) in 1995 to more than 170 (a 70% increase over the norm) in 2005. Rising prices for steel and crude oil are also reflected in manufacturing and shipping costs, and yet consumers keep demanding lower prices. Ford has announced that all of its models will increase $400-$600 in 2007 just to pay for end-of-life compliance expenses. So, what can be done to balance or lower these cost issues?

Challenge drives innovation; thus, Ford, and every other car manufacturer, is now thinking differently about every piece of plastic that goes into its vehicles. They’re asking themselves:

• What do the raw materials cost?
• How environmentally benign is the processing and handling?
• What energy does it take to use this material?
• Is there a material that costs the same but is easier to recycle?
• Is there a new material that is so strong we can now use less of it to make an existing part with the same durability?

At the same time, many different industry and government groups have developed numerical methods for evaluating the relative environmental impact of different material, processing, and transport choices. Universities, too, such as MIT, are not only looking at energy methods and new design methods, but are starting up whole new departments that combine different disciplines for sustainable development.

Lifecycle Analysis and Planning

Looking at the big picture is a great way to identify specific product design tasks that can be reevaluated to lessen their contributions to the overall environmental impact. For a product manufacturing process, a lifecycle analysis (LCA) identifies the energy and waste (solid, airborne and waterborne) associated with each relevant stage, including:

• Raw material extraction
• Material processing
• Component manufacturing
• Assembly & packaging
• Distribution & purchase
• Installation & use
• Maintenance & upgrading
• End-of-life:material recycling
• component reuse
• product reuse
• land filling
• incineration

One interesting and very timely attempt to quantify such factors for design decisions comes from a partnership between the Industrial Designers Society of America and the US EPA. Their project, called Okala, is currently updating its list of calculated “impact” values for hundreds of materials and processes. For example, one assigns a value of 140 to a product if the material used is aluminum, while switching to the use of ABS plastic (which takes less energy to process in the raw form) brings the impact down to 47.

Dozens of savvy, worldwide companies have already put years of efforts into incorporating some or all of these design elements in industries ranging from furniture and flooring to telecommunications and tools. For example:

IBM started implementing a formal, ISO 4001 environmental management system across all of the company’s global manufacturing and hardware development operations and all its business units more than ten years ago, building on previous efforts to ensure environmental considerations are a routine part of all business decisions.

BMW’s recycling center takes new car models and dismantles them, testing the effectiveness of the disassembly process, as some parts are designed for re-use and others for recycling. The group feeds information back to the design center.

Specific Product Design Efforts

Since the term sustainable design can refer to many different areas of product design, as well as end applications, following are details of several companies and their products, stepping through the thought processes that produced improved products with better financial and environmental impacts:

Medtronic

In physiology, “perfusion” is the term for quantifying how much of a necessary nutrient (such as oxygen) a person’s blood is actually delivering into a patient’s system. Medtronics Perfusion Systems group manufactures a line of products, used during cardiopulmonary bypass surgery, that help control this factor by providing circulation, temperature control, filtering, and supplemental oxygen. The systems must operate with consistent, efficient gas-transfer, minimized blood shear, low priming volume and low blood-side pressure drop.

Perfusion Systems has incorporated design-for-the-environment (DfE) procedures into its complete design-control methodology. This process has already generated a 75-85% reduction in chemical use and wastewater loading for a coating process during manufacturing, with an annual savings of $2.1 million. In addition, the company plans a 30-35% reduction in material use and a 90% reduction in industrial solid-waste generated in a battery-manufacturing process. The potential annual savings with the latter approach is over $200,000.

Apple Power Mac G4 Desktop Computer

A case study in 2000 of the Apple Power Mac G4 Desktop Computer described the company’s systematic approach to sustainable product design.

Here are a few of the improvements achieved by making changes in the following design attributes:

• Energy conservation - reduced thermal profile allows fans to turn off during sleep; sleep-mode power usage is less than 5 watts (just 17% of the ENERGY STAR 30-watt requirement)
• Materials conservation - compared to previous products, the Mac G4 used 50% fewer components on the universal motherboard; eliminated sliders and skids for attaching zip drives and CD ROMs to chassis
• Hazardous constituents - lithium battery contains no heavy metals; no chlorofluorocarbons (CFCs) or other ozone-depleting compounds used in manufacture
• Design robustness - continued use of standard modular components across different products; also incorporated industry-standard components
• Ease of service, repair and upgradeability - all components accessible via swing-open enclosure side door; processor easily removable, replaceable and upgradeable; key components changeable in one minute
• Ease of disassembly/recycling - screw count reduced from eleven to two for mounting motherboard to chassis (reduces time and cost); metal chassis and polycarbonate plastic skin enclosure easily separated for recycling

Automotive Material Reductions

Low cost and improved safety are two factors that can coexist in product design with excellent results, given a detailed, accurate analysis of mechanical form coupled with material properties. One automotive company recently used FEA to assess the design of an end-link bracket that connects the sway bar and control arm in a vehicle suspension system to possibly cut down on material use. The ripple-effect implications would involve saving money by allowing the purchase of smaller quantities, as well as using less energy to produce the material.

Made of reinforced nylon, the mostly solid, injection-molded part as originally designed had a minimum safety factor of 3.4, and cost $0.65 each. The company analyzed the resulting stresses and functional limits when redesigning the part to have six through-cut slits, reducing its mass from 0.234 kg to 0.205 kg.

Lasting Benefits of Sustainable Design

Although there may always be tradeoffs when evaluating the details of sustainable designs, the long-term benefits (and we must look long term) are undeniable:

• Reduced impact on the environment
• Use of clean technologies for everyday living, construction, and manufacturing
• Reduced water treatment costs
• Less waste going to landfills
• Soil, air and water pollution prevention
• Preservation of forests and biodiversity
• Reduced climate change
• Product reuse or recycling at end of life

Tradeoffs are best analyzed with precise software products, whose results can be repeated, shared and analyzed by all departments in an organization, from design and manufacturing to marketing and transportation. Forward-planning companies are more profitable than reactive, defensive companies, and those that improve their competitive position may also keep jobs from going overseas. Software that enables sustainable design processes at all stages of a product’s life-cycle is a critical tool for successfully operating in today’s design environment.

The author is Vice President, Asia Pacific, SolidWorks Corporation