Punch “sustainability” into an Internet search engine and it will spit out over 33 million entries. So it must be a pretty important concept, right? It’s on the cover of magazines, corporate boards are scrambling to put vice presidents of Sustainability on company payrolls, and there’s undoubtedly an uptick in the number of sustainability consultants hanging out shingles.

But what is sustainability and what does it mean for engineers and the companies they work for.

A definition
It’s hard to strive for a goal when you can’t define that goal. That’s one of the problems with sustainability. And the only thing worse than no definition is having too many. “There are literally hundreds of definitions for sustainability,” says Prof. Larry Nies, an instructor in Purdue’s engineering program who teaches a course called Engineering environmental sustainability. “At the conceptual level, environmental sustainability means society should consume only renewable resources and only at a rate less than their regeneration capacities. And society should discharge waste at rates less than the capacity of the environment to assimilate them and continuously recycle nonrenewable resources (such as metal). Sustainability also involves not depriving future generations of resources or the environmental quality we enjoy today. Thus consuming fossil-fuel-based energy is in no way sustainable. Not using fossil energy is impractical right now, but conserving it and thinking about ways to switch to renewable energy is a good start.”

Nies points to two examples of sustainable technology: Cell phones and the Internet. “Cell phones have revolutionized communication, especially in the developing world,” he says. “No longer are land lines required to bring telephone and data services to remote locations. All that is necessary are transmission towers. Cell phones, however, raise sustainability issues specific to their product life cycle, but overall, they have made communication technology more accessible and sustainable.”

“The Internet lets people do many things, such as reading newspapers online and downloading music and movies. Think of all the paper, material, energy, and packaging this saves. The evolution of the Internet has not been without hitches, but overall the sustainability of information delivery is dramatically improved,” says Nies.

Prof. Cliff Davidson, a civil-engineering instructor at Carnegie Mellon University and public policy director of the Center for Sustainable Engineering, agrees there are hundreds of published definitions with a variety of meanings. “A single definition understood by all does not exist,” he says. “This sometimes leads to communication problems when discussing the term. Our organization frequently refers to a well-known definition from the World Commission on Environment and Development, a U.N. organization also knows as the Brundtland Commission. Its 1987 report, Our Common Future, defined sustainable development as: “Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”

That seems to be the definition of choice, despite the fact it is ambiguous, giving no clue as to how to determine future generations’ needs, let alone identify current needs.

What can companies do?
For most companies, sustainability means conserving energy and raw materials, goals any company should have as they both increase the bottom line. Bayer Corp., for example, which has earned kudos for its work fighting climate change, recently instituted Climate Check, a way to measure manufacturing processes based on energy efficiency and CO² emissions. It will also compare the energy and carbon usage associated with raw materials, energy, and logistics. Bayer says it will examine the “climate footprint” of its manufacturing plants and make efforts to reduce it. But if sustainability costs money rather than saves it, will companies like Bayer take a cut in profits or will it pass the cost on to consumers?

“Conserving energy or water saves money. It is really that simple,” says Nies. “However, there are capital improvements that can be made in the name of sustainability which might not pay back profitably by conventional economic analysis. True sustainability involves triple bottomline accounting which includes finances, environment, and social capital. Environmental externalities are easy to quantify but difficult to value. Likewise, social capital, such as public reputation and standing as a community citizen, is difficult to value but many companies still want to market their ‘green’ image. It’s part of social capital.”

There are other ways to approach sustainability. “Profit is often maximized by selling as many products as possible, which favors designing products that have to be replaced frequently,” says Davidson. “This is usually incompatible with minimizing environmental impact. One idea for getting around this problem is to encourage companies (or regulate them) to change their mode of operation so that their products are leased rather than sold. A company thus benefits if it designs products with long life spans. The company is thus selling a service rather than a product.” Leasing would also give companies incentives to make their products easy to take apart and recycle.

Quickly adopting new technologies can also let companies use energy more efficiently to both save money and reduce environmental impact. “Many companies use methods that are inherently inefficient and environmentally damaging, simply because those methods were the only ones available years ago,” says Davidson. But it would help if the government restructured the tax code and environmental regulations to make it easier for companies to upgrade equipment.

No matter what approach a company takes, it must have some way to measure performance towards sustainability if it is serious. “Typically they focus on energy or water conservation. They conduct an audit to form a baseline and discuss goals the company would like to achieve and why. It then develops a plan. Companies can also focus on small issues such as how to apply vacuum to a specific operation, or should there be plastic disposable cutlery or reusable metal cutlery and a dishwasher in the employee cafeteria?” says Nies.

New products and engineering
“When it comes to products that companies sell, one important principle of sustainable engineering is that environmental effects of a product should be minimized in all phases of its life cycle, from extracting raw materials, manufacturing, using the product, to ultimately recycling it or properly disposing of it at the end of its useful life,” says Davidson. “By environmental effects, I mean the use of raw materials and energy, as well as the discharge of wastes. Thus, environmental effects, in addition to traditional constraints like cost and safety, need to be incorporated into the decision-making process.”

Nies concurs. “If a company considers the entire product life cycle, an ambitious undertaking but many companies do it, designers must consider the environmental effects of acquiring raw material and transportation, waste generation, and water and energy consumption, packaging, product performance, and the fate of the product at end of life.”

But as many engineers will say, they merely try to do what their employers pay them to do. They have little say in company philosophy or how management prioritizes goals.

“Still, companies must make choices to develop products that are more sustainable than past ones,” says Davidson. “This will take a great deal of research into the environmental effects of alternative materials, designs, and production methods. And after collecting this information, decisions will still involve value judgments and assessing uncertainties.”

“One tool companies could use to design for the environment is Life Cycle Assessment,” says Nies. “And although many companies are mystified by the assessment phase in an LCA, they might understand and accept it more readily if they knew they could define the goals rather than using one of the already existing assessment frameworks. For example, rather than using a full spectrum-assessment framework such as Eco-99, perhaps they only want to focus on their carbon footprint.”

Some advocates of sustainability believe engineering students need to know more about it, despite a lack of evidence that companies are looking for that kind of knowledge in engineering hires.

“Sustainability should be incorporated into essentially all engineering courses because all engineering decisions have associated environmental impacts,” says Davidson. “This is a major challenge, as most engineering courses have been taught the same way for a long time and do not include sustainability issues. Furthermore, engineering textbooks generally do not include material on sustainability, and thus instructors must make an extra effort to track down information relevant to their particular course. Some universities offer separate courses that deal with sustainability, and this is certainly a start. But it would be far better for these concepts to be built into all engineering courses so students learn to consider sustainability in solving any real-world engineering problem.”