Sustainability metrics

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In the next of his sustainability articles, Chris Sherwin tackles the question of how designers can go about getting their sustainability metrics right. It’s certainly not as straightforward as it may seem
This week, a colleague asked the question every environmental consultant dreads: ‘what are the greenest materials, or best eco-options for my product/project?’ Annoyingly, we tend to answer: ‘it depends’.

It depends on a bunch of context specific things like how a product is used, disposed of or where materials are sourced. But chiefly it depends on how you interpret green or ‘eco-options’ as the environmental sciences behind this are complex, featuring many factors and frequent trade-off s.

Underneath that are questions of sustainability metrics i.e. how we ‘measure’, determine and understand impacts, which is worth unpacking further.

Different shades of green

Ask a climatologist this question and he’ll prioritise climate change, prioritise carbon (CO2) or Greenhouse Gases (GHG) and make recommendations on that metric.

A material scientist would say depletion of resources or waste. A toxicologist’s recommendation may favour hazardous substance metrics for their impacts on human or ecosystem health.

Frustratingly, these seemingly related environmental metrics sometimes don’t line up so you can positively affect one area (carbon footprint), but negatively affect another (depleting non-renewable resources).

In the end it’s about setting a priority or lead issue, which is a value judgment. Whilst that might sound fl aky and subjective, you can make informed and conscious choices.


Carbon – universal design metric

If it’s a quick and dirty sustainability metric you are looking for, carbon or GHG emissions may be the one for you. Many of my environmental colleagues believe that carbon or CO2 (think footprints) has now entered the mainstream.

There are obvious dangers in picking a simple, single metric, but it has worked in parallel worlds, notably health and nutrition. There are lots of metrics for the nutritional value of food, like fat, fibre, salt, carbohydrates, etc, but ‘calories’ is the most widely accepted indicator.

Carbon is to sustainability what calories are to health and nutritional metrics – a proxy measure giving a rough, indicative picture of broader impacts.

Metrics in packaging design

A more in-depth look at a specific design sector such as packaging might help land some of this. Historically, weight has been the most widely used sustainability metric (i.e. total pack weight or product/pack ratio) sometimes supported by volume metrics.

More recently the carbon footprint of packaging has become a widely used indicator (The Courtauld Commitment, an initiative from the Government’s Resource Efficiency body WRAP, uses a weight and carbon combination for UK packaging target) while material issues like renewable or recycled content or a materials chain of custody (sustainable sourcing) are increasingly prominent.

Corporates are becoming more sophisticated too, as a look at two packaging giants illustrates. Unilever‘s target is to “halve the waste associated with the disposal of our products by 2020” with the metric itself tracking product and packaging wasted per unit of consumer use.

The metrics behind P&G’s 2020 packaging goals are to “replace petroleum-based materials with 25 per cent sustainably sourced renewable materials and to reduce packaging per consumer use by 20 per cent.” Many designers use Lifecycle Assessment (LCA) tools for sustainable design, which pretty much takes the metrics question out of their hands.

There really is no single, simple answer to the metrics question, it’s a bit of a holy grail and it really does ‘depend’ on your priorities and context

These tools, widely used in packaging, help quantify the impacts of design choices by measuring their effects on the environment via issues like acidification, eutrophication, terrestrial eco-toxicity, ozone layer depletion, human toxicity etc.

Comparison is the main use of this as designers compare different options for their effect on the different indicators, though comparison across different indicators remains a challenge. Single scores have been derived from this (like Eco-indicator ’99, Okala or ecological footprints) but these too feature value judgments as part of their impact assessment ranking, leading us back to square one.

The most comprehensive list of all this comes from the Consumer Good Forum’s Global Packaging Protocol, featuring roughly 25 indicators split across ‘Environmental attributes’ like packaging weight and optimisation, recycled/renewable content, as well as a list of ‘lifecycle indicators’ derived from LCA highlighted above.

Design counts

This all tells us that there really is no single, simple answer to the metrics question, it’s a bit of a holy grail and it really does ‘depend’ on your priorities and context. What’s a designer, looking for clear directions and answers, to do about this?

I would start by knowing your client’s metrics. If they didn’t specify them directly in your project or product, they may have corporate ones you could use (like to be carbon emissions, waste, material use and water), or better still a sustainability department full of people measuring and monitoring exactly this stuff . They’ll be happy to help and be really experienced at this too.

A suite, rather than a single metric, usually gives a fuller picture, so consider using more than one. If these cover carbon/GHG’s, toxicity and some combination of resources/material use/waste, you won’t be far wrong in my opinion. You will need to set priorities though, and have one metric leading, and at the moment it’s hard to see past carbon.

On top of that, a lifecycle perspective is essential, using metrics that cover even the hidden design impacts – raw materials, production, distribution, use and disposal. And I think it’s also OK to allow your LCA software tools to answer some of these tricky metrics questions, as long as you are at least broadly aware of what is going on inside the black box.

Returning to our opening request, not answering a simple question can lead to confusion and frustration, but sometimes it’s OK to highlight complexity in the answer.

Chris Sherwin gets the measure of green design

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