How does material intensity help measure sustainability?

The hierarchy of sustainable practices in terms of highest to lowest value goes from reduce to reuse, recycle and, finally, responsible disposal. The most beneficial sustainability practice is reduce.

In other words, the best way to protect the environment, reduce pollution and increase sustainability is to use less of everything in the first place. In that way, less energy and fewer materials are consumed, and there is less scrap, waste, effluents and emissions to try to reuse, recycle or dispose of.

Material intensity is a globally recognized measure of materials needed for the production, processing and disposal of a unit of a good or service. In the United States, material intensity is tracked by the Federal Reserve Economic Data group as a measure of manufacturing activity. The Bureau of Labor Statistics also uses national material intensity measures as part of its regular reports on business health. Similarly, material intensity is tracked by the United Nations for countries and regions.

On a national or global level, material intensity measures factor in the amount of materials used per unit of economic output, primarily gross domestic product. Such broad measures necessarily combine a number of independent factors, like product mix and technological changes, that make it difficult to isolate any sustainability trends, especially when looking at long time periods and dissimilar economies. Nevertheless, in a more isolated view where these other factors might be more stable, a change in material intensity might indicate changes driven by sustainability improvements.

On a company or industry basis, material intensity can be a clearer indicator of sustainability, especially when looking at changes and trends within a given company or industry. A simple calculation would be the amount of material used divided by the volume of product sold.

The way the ratio is calculated and used in the community, however, is a bit more complicated: Material intensity = cost of material input per unit of value added. Arguably, this definition is vulnerable to changes in material costs and can be challenged by varying definitions of value added, so be sure these factors are clearly defined and consistently applied over the entire period of monitoring and comparison.

Much like the familiar and popular inventory turns ratio, material intensity can be used as a measure of beneficial change over time. Most companies monitor inventory turns rather than gross inventory level as a way to view how well inventories are managed, while eliminating the effects of changing sales volume. Material intensity keeps the indicator neutral, so to speak, by comparing material usage to a measure of the amount of product produced.

A somewhat different definition of material intensity is pounds or kilograms of material wasted per unit output. Waste is calculated by subtracting the weight of products and coproducts from the weight of raw materials input. Water is not included in the calculation, and that could be a significant issue with certain kinds of products.

You can use variations on the specifics of material intensity and related measures, such as carbon intensity, energy intensity, emission intensity, non-renewable materials intensity and the like focus on more specific process inputs, and apply the same general approach by using a ratio of input to volume of production output to identify progress toward a goal of increased sustainability.