The Metrics of Sustainability

Assessing the sustainability of products and materials is trending toward a quantitative approach.

By Carol Derby


ere's what I remember about the first green products taking the stage 10 or 12 years ago: they came with stories. Whether in the form of carpet, flooring, or textiles, we often connected with narratives about invention-how an environmentally preferable product had come about, usually from some previously overlooked raw material.

The introduction of the first post-consumer recycled polyester fiber made from plastic bottles came with display packets of bottle chip and its extruded fiber, some of it identifiably Sprite green. Particle board was celebrated for its brilliant use of a pre-consumer material called sawdust that lumber yards had previously paid to have hauled away. The development of the world's first biological-nutrient textile, a chemically optimized wool and ramie blend, was the story of a mill taking waste that had been deemed hazardous and turning it into food for farm soil. Even the standardized way of reporting on the sustainable attributes of a product, ASTM E2129, "Standard Practice for Data Collection for Sustainability Assessment of Building Products," as the title might suggest, invited answers in the form of short essays.

While these stories haven't gone away, I haven't been asked for an ASTM E2129 in a while. What I am routinely asked for is a percentage breakdown of post-consumer versus pre-consumer content and the distance, in miles, from the manufacturing location to the project. I also get asked for VOC emissions data, or more accurately, for certification that a product is low-emitting. With regard to greenhouse gases and climate change, I haven't been asked for the CO2 equivalents of virgin versus recycled polyester yet, but I'm getting ready.

Whether it's because some stories were suspected of incorporating greenwash, or because a demand for greater efficiency has moved stories to the background, what seems clear is that the pendulum has swung from a qualitative view of green building materials to a more quantifiable one. Number crunching, it seems, is what the green market demands today.

Perhaps the first metrics appeared as part of the "nutrition labeling" approach that has afforded greater transparency in the green products market. As we've understood more about the environmental characteristics of our products, we've begun listing their ingredients-making quantifiable claims about percentages of recycled, rapidly renewable or organic content. Having established what went in from an environmental health perspective, we then began looking at what to keep out from a human health perspective. Screening materials for chemicals of concern is becoming more common, with assessments typically done at 1,000 parts per million (ppm), as well as the more rigorous 100 ppm close-up that newer standards and certifications encourage.

Chemical analysis is a convincing way to measure a material's potential impact on the environment. In textiles, the negative list includes chemicals that could leach, offgas, release upon incineration, or break down with UV exposure, and consumer awareness of a few classes of toxins is on the rise. Heavy metals form one such class. These can show up as catalysts in the polymerization of polyester and polyethylene, or in added dye stuffs and flame retardants.

Increasing focus is also being placed on persistent biological toxins (PBTs), like halogenated compounds, which have been shown to build up in the environment and work their way up the food chain. Rising concern about the health risks associated with heavy metals and PBTs, among other suspected toxins, has increased our reliance on measuring for their presence. Even as some toxicologists work to determine whether there might be safe exposure levels for some of these chemicals, establishing presence alone is often enough to incite some specifiers to embrace the Precautionary Principle and move to more benign alternatives, where they exist.

Running parallel to measurement of human health risks, a new sense of urgency relative to climate change has been the catalyst for measuring the release of greenhouse gasses (GHG), often to arrive at a person or product's carbon footprint. As retailers of food and apparel have begun to label products in this way, consumers are able to choose between, say, two T-shirts: one whose process energy produced 6 kg of CO2 and another that, through the use of renewable energy, saved the same amount of carbon emissions. But consumers will have to base their decisions on process energy alone, because a chain of national stores will not likely be able to report on the transportation energy used to get each T-shirt onto shelves that are thousands of miles away.

The trouble with all this data is that it can to lead to decision-making paralysis. For instance, Life Cycle Assessment (LCA) data typically measures 12 impact categories ranging from human toxicity and habitat destruction on a local level, to resource depletion and GHG effects on a more global level. Each impact category represents a segmented view. Bringing it all into balance often involves some subjectivity on how to weight things like GHG emissions that cause global warming versus VOC emissions that compromise indoor air quality. So while LCA data can provide us with confidence within a well-defined scope, it isn't necessarily easily added up or compared.

Perhaps it's helpful to remind ourselves that the human pursuit of sustainability is a newly rediscovered science (perhaps practiced at a higher level by earlier civilizations) and true sustainability is an infinite process. It shouldn't surprise us then that our extrapolations yield approximate and partial answers. Rather than feel defeated by this, many industry individuals are undertaking the humbling task of establishing baselines. This is one of the attainable goals of several industry-specific sustainability assessments (for carpet, furniture, and textiles) that are coming to market. Before we can interpret mountains of data about a product's water and energy use for instance, we need to know the typical meter reading for that type of production. By rewarding manufacturers for undertaking these kinds of audits, we can start to establish the necessary benchmarks from which all future improvements to water and energy use can be gauged.

We can also keep the metrics of sustainability in perspective by viewing them in the context of some of the system-thinking approaches to sustainability. In recent years, for instance, The Natural Step, a rule-based system that eschews metrics, has been brought in to provide a context for employing the LEED® Rating System. In the words of one architect trained in both disciplines, The Natural Step provides the contextual "framework" for using a LEED "yardstick." The Pharos Project is another methodology that, while grounded in metrics, has proposed a highly visual and intuitive approach to presenting the data-displaying the segments of a product's life-cycle in a wheel format that communicates a material's environmental strengths and weaknesses at a glance.

I think it's safe to say we are richer for an understanding of sustainability that incorporates both qualitative and quantitative measures. For instance, the aforementioned particle board story can, on its own, stand as a
model for sustainably sourced surface materials. The potential for some particle board to contain formaldehyde (a carcinogen) as a binding agent isn't something we would necessarily know from the story, but it is something we could learn from a VOC emissions test. In this way, our quest for the quantifiable may eventually produce enough data, properly sorted and balanced, to form the foundation of a new kind of ASTM E2129-not just a "Practice for Data Collection," but a practice for data synthesis. Finite results can plot the points for the next green material innovations. Those stories, I'm convinced, will lay the yardsticks of conserved resources and reduced impacts into a framework. There will be stories that begin with an old way of doing things (the baseline), continue through measured improvements, and arrive at some newly attained benchmark ... inspiring the next innovator to begin the sequel.

Carol Derby is the director of Environmental Strategy for Designtex, a supplier of surface materials for commercial interiors. She also serves as the president of the Association for Contract Textiles and is a member of the Joint Committee of the Sustainable Assessment Standard for Commercial Furnishings Fabrics, which is currently being developed as an ANSI voluntary consensus standard. She can be reached at



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