The following is Part 4 of our blog series on Zero Waste, written by William F. Hoffman III Ph.D., Senior Scientist and Corporate Fellow at UL Environment.

In my last blog entry I talked about recognized diversion routes and the overall goals of the UL ECVP 2799, Zero Waste to Landfill program. This week I’m dedicating the blog to explaining how to calculate Reduce and Reuse.

Reduce and reuse are probably two of the more difficult diversion routes to calculate. Reuse is slightly easier, although the record keeping is different from other diversion routes. In the case of reduce, it is also a comparative measure; a before condition and after condition have to be compared to come to a final diversion amount. There are two methods to calculate the amount of diverted waste for activities that reduce the amount of waste created – process and project.  Fundamental to either method is the ability to track the reduction in relation to a unit of operation, usually units produced. In the project basis, the savings is calculated based on individual project outcomes and the savings per unit production. For a process basis, the waste diversion is calculated by tracking the amount of waste generated before and after the reduction on a unit production basis or other metric related to the rate of waste generation.

The general steps are:

  1. Define the process and measure baseline performance (waste per widget produced).
  2. Make improvements to process.
  3. Measure new performance and track new usage rate (reduced level of waste per widget produced).
  4. Calculate reduce as (old waste/widget)-(improved waste/widget) *number of widgets produced.

For each widget produced in the time period of the audit, a unit reduce diversion is credited to the results and is added to both the diverted materials and discarded materials. Notice that to calculate the benefit over the course of the audit period, the number of widgets must be tracked.

In the project basis the benefit is calculated based on a comparison of waste generated before and after the project is implemented.

  1. Define the project and measure baseline performance (waste per widget produced).
  2. Implement the improvement project.
  3. Measure current performance and track new usage rate (reduced level of waste per widget produced).
  4. Calculate reduce as (old waste/widget)-(improved waste/widget) *number of widgets produced.

The difference between project and process basis is that the process basis often includes multiple projects in the process improvement and those projects do not have to be measured and documented separately. Projects can only be used in one reduction benefit though, process or project, not both.  Reduce or reuse projects can be used for as long as the product/process or change is active. In the case of process-based change it is only good until the next process change.

The diversion mass for reuse is calculated based on the continued use of a resource that was formally discarded or would be discarded if not reused. The steps are much simpler for reuse since no baseline measurement is required. Again a unit of usage related to the mass of materials being reused must be determined and tracked.

1)     Measure the mass of the materials to be reused on a unit usage basis.

2)     Measure the total number of reuses for the time period being audited (number of widgets produced).

3)     Calculate the savings by multiplying the number of reuses (widgets produced) times the mass of material reused.

The easiest example would be a part tray which is reused. Each time a product is completed, one part tray can either be discarded or returned to the assembly line and filled with parts. When the tray is returned for reuse each product completed results in the mass of one tray being reused.

For a look at some of the issues around zero waste and why UL created the Zero Waste validation procedure, please download the UL Environment White Paper on Zero Waste.  Next week the blog will cover calculations and estimating material stream diversion amounts.