Calcuatling the Sustainability of Alumninium Packaging

In our 2013 Sustainability Report, we recast the data from 2007 through 2012 to normalize usage and emissions per billion units produced. This change was made to present data that offered greater insight by adjusting for year-to-year changes in product mix. We used this same approach to calculate data for 2013 and 2014, the reporting period covered by this report.

Since we manufacture a variety of containers in different sizes, using different metals and serving different markets, along with ends, vacuum closures and crowns, we developed a set of conversion factors to transform these container and closure production volumes into 12oz. (Ø211) aluminum beverage can equivalent volumes, or “units.” This modification more accurately represents our efforts to conserve raw material use and reduce emissions over time. 

The three conversion factors are explained in more detail below.

  1. Type of metal: This factor relates to the specific gravity of the material used in the container, with 1.0 for aluminum and 2.9 for steel.

  2. Product functional requirements: This factor adjusts for the fact that different market applications (i.e. beverage cans, food cans and aerosol cans) use different amounts of metal for the same sized can due to very different performance requirements such as pressure performance. These values were determined by comparing the amount of metal required for an approximately 355ml container across different applications. For beverage cans, the value is 1.0; for food cans, the value is 1.5; and for aerosol containers, the value is 2.0.

  3. Container capacity (fluid volume): We used three different approaches to correct for the extra raw materials required for different sized containers/closures:

    • For a 2-piece container, we used the weight of different sized containers. This is because height changes have a relatively smaller impact on metal utilization for such containers, as the thinnest part of the container is expanded or reduced to change size, with little change to the top and bottom of the containers.

    • For draw/redraw and 3-piece containers, we simply used the volumetric capacity of the container to determine the conversion factor.

    • For our metal (vacuum) closures, we determined the correction factor directly from the weight of the closure derived from our cut edge and thickness data.

Some illustrative examples, representing some of our more significant production volumes, are provided below.

  • A single 16oz. (Ø211) aluminum beverage container would be converted into 1.33 standard "units."

  • A 330ml (Ø211) steel beverage can would be converted into 2.694 standard "units" (0.929 due to volume times 2.9 due to material).

  • A Ø300 x 409 steel food can would be converted into 2.685 standard "units" (1.79 due to volume times 1.5 due to the functionality).

  • A Ø57x164 aerosol can would be converted into 2.36 standard "units" (1.18 due to volume times 2.0 due to the functionality).

The functionality factor was validated by comparing typical weights as per example:

Container Size Brim-full Gauge Weight (g) Ratio
Beverage steel can 65x101 355 0.22 21.62  
3-piece food can 65x112 355 0.14 body / 0.17 NEO 32.14 1.48
3-piece aerosol can 65/60/63x112 355 0.20 body / 0.30 bottom 44.86 2.07

Given the large range of containers we produce, we needed to make some simplifying assumptions. In all cases, these assumptions will not have a material effect on the outcome.

  1. For every 2-piece container, we produce one end and for every 3-piece container, we produce two ends. This is a very good approximation as it is very nearly the case, but is not exactly true in all circumstances.

  2. We have eliminated the data (the raw material usage and the number of unit containers sold) from our Specialty Packaging Business Unit as it represents < 5% of our total revenues. We have done this since the types and volumes of products in this business segment vary greatly, from very small containers to 45 gallon drums, and because the product mix can vary dramatically from year-to-year.

We are happy to share more details on this approach with other canmakers, as we believe the method represents a significant improvement in the way to represent the relative amount of raw materials produced and emissions generated in a changing marketplace.

In recognition that this normalization methodology is unfamiliar to those outside of Crown, we are working to obtain third-party validation and will report on results of the evaluation separately.

The report does not include environmental data from our specialty packaging plants and our CMB Engineering equipment and tooling division since there is too much variability from year-to-year in their product portfolios to allow the effective normalization of data and together they represent less than 5% of Crown’s overall revenue. However, the employment demographics, safety performance and other elements of the social category of sustainability are included. This is consistent with how we reported data in the 2013 Sustainability Report, so there are no significant changes from previous reporting periods to highlight or explain. 

Assets gained from the acquisition of Mivisa Envases, SAU in 2014 are also not included in this report since these plants were not operated by Crown during the entire reporting period and it was not possible to segment their environmental, production or employment data. However, all of the data from the Mivisa plants will be included in future reports.