Sustainability is slowly but surely becoming a central factor in decision making across many fields, particularly in material design and material selection. Manufacturing processes and materials are increasingly required to comply with sustainability metrics that measure their impact on three major areas: the economy, the environment and social equity. The aim is to positively impact the economy and society with no permanent damage caused to the environment. This is where sustainability indicators come into play.
Although they can be quite complex and subjective - sometimes even intangible and difficult to accurately measure - their importance is, without question, immense. This had led to the creation of a wide range of indicators by many different bodies to help measure sustainability.
According to Joung, Che B. et al. , at least 11 major standards are developed to measure sustainability. However, their methods could be different and may arrive at conflicting or inconsistent results, which is a testament that sustainability measurement is yet to be considered an exact science. The challenge for the future is to create a more unified and harmonised standard that can aggregate all the best indicators to give more consistent and reliable sustainability measurements that everyone can adopt.
In this article, you will learn about:
Sustainability indicators are metrics that define how sustainable a given process or a certain material is. As their name implies, they indicate the level of sustainability that can be allocated to a process or material based on specific standards.
As sustainability is measured by evaluating:
...a process or a product may do well in one or more of these evaluations, but not all. It can score well in one or two areas and fail in the other area so catastrophically that the overall conclusion would be that the process or product is not sustainable.
Due to a mix of government regulations, customer desire to use sustainable products, and companies’ commitment to incorporating sustainability in their manufacturing processes, a lot of products, nowadays, can be deemed sustainable or at least more sustainable than they were before. Materials produced with sustainability in mind include wood, metal alloys, resins, and thermoplastics and are made by companies committed to sustainability, such as Sabic, Perstorp and Gränges.
Diagram showing the three overlapping pillars of sustainability and their broad indicators
Since indicators are essentially datasets that must be fed into a larger algorithm or formula to produce a result, they must fulfil certain criteria to be considered good indicators. Such criteria include but are not limited to  :
Sustainability indicators are numerous, diverse and can be defined in different ways, allowing them to be categorised under different umbrellas. They can be :
Quantitative indicators can be measured with numbers easily apportioned to them. They indicate aspects such as the volume of CO2 and greenhouse gas emissions, toxic waste, etc.
Qualitative indicators, on the other hand, are very subjective and cannot be measured physically. They require interpretations that are agreed upon and include measurements of intangible things such as improvement in cultural values and social equity.
Absolute indicators denote the impact of a product or material with a numerical value such as total energy consumed or total waste generated. However, unlike relative indicators, they do not give any context to show the trend in sustainability.
Relative indicators present a comparison between one absolute indicator and another absolute indicator, thus providing more sustainability context. For example, if a production process reports a reduction in total energy consumed by 50% over a certain time, it may seem positive at first. But by adding the information that the production rate was down by 60% in the same timeframe, that points to a reduction in efficiency as even more energy has been consumed to make the same product. This is why there has been a greater shift towards using relative indicators more commonly in sustainability measurement.
General indicators cut across multiple fields worldwide and can apply to a wide variety of operations and materials. These indicators may include contribution to climate change, water and energy usage, etc. They make it easy to compare one product or process to another as they share common indicators for comparison.
Specific indicators, however, are niche indicators that do not apply to most other fields. Such fields include space exploration, petrochemicals, etc.
There is hardly any majority consensus when it comes to the metrics of sustainability. Over time, there have been dozens of published indication sets by different bodies which include universities, standards organisations, government institutions, and more. Some examples of the most prominent and widely used standards include :
The National Institute of Standards and Technology (NIST), in response to the myriad indicators in sustainability measurement, developed a model to categorise these indicators so that they can be grouped into divisions and sub-divisions. This endeavour provided much-needed structure to the indicators for stakeholders to choose from.
Five major categories were created with 212 indicators in total:
 Joung, Che B., et al. "Categorization of indicators for sustainable manufacturing." Ecological Indicators 24 (2013): 148-157.
 Moss, M., and T. Grunkemeyer. "Using resident formulated multi-dimensional indicators to assess urban communities." Progress Toward Meeting Sustainability Goals,” Proceedings of the International Conference on Whole Life Urban Sustainability and its Assessment, Glasgow Caledonian University, Scotland, UK. 2007.
 Garrett, Rachael, and Agnieszka E. Latawiec. "1. What Are Sustainability Indicators For?." Sustainability indicators in practice. De Gruyter Open Poland, 2015. 12-22.
 Bae, Hyunkee, and Richard S. Smardon. "Indicators of sustainable business practices." Environmental management in practice 177 (2011).