Green Consumption and Green Manufacturing

by | Mar 9, 2011

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Recent postings have been discussing the connection between the use phase impact of a product and the manufacturing phase impact and what influences these. This was in the context of both looking at means to reduce consumption (meaning giving the consumer products that deliver the required functionality or service but at a lower environmental impact or energy/resource consumption.)

There are a number of places along the product development chain that critical decisions are made that have a positive or negative influence on this impact. Last time we were talking about whether or not the rule of thumb that 20% of the design influences 80% of the cost of a product also applies to the energy/resource impact. I thought that, in many cases, it didn’t work that way.

There is, by the way, a great study on this from 1993 written by some MIT researchers (Karl Ulrich and Scott Pearson) titled “Does product design really determine 80% of manufacturing cost?”  and they tease this comment apart with some case studies and analysis. The report attempts to determine how much product design influences the manufacturing cost of a product. They study this for a class of high-volume, electromechanical consumer products — automatic drip coffee makers – and they find “that for coffee makers, the variation in manufacturing costs attributable to differences in product design is slightly smaller in magnitude than the variation in costs attributable to differences in manufacturing systems, for a specific range of assumed manufacturing system parameters.” They note that the “rule of thumb” is specially flawed where the dominant cost contributor is the cost of materials. Further, they note that “There is also a basic logical flaw in the argument that if the minimum possible manufacturing cost is 80% of the maximum possible manufacturing cost then product design is a critical activity of the firm. The flaw arises from the assumption that much of the 80% of the cost of the product is under the control of the product designers.”

I was not going to get into that but I agree. But, for now, we are concerned with the influence of design vs manufacturing on the life time product energy or resource impact.

So, back to use vs manufacturing impacts. You might recall this discussion recall blogs ago. We can actually visualize this use vs mfg impact space in terms of what needs to be done depending on where the product sits in that space. In the figure below, we can see four quadrants of “sustainable product” characterization.

The axes are the same as in the use vs manufacturing discussion and indicate, from low to high, the consumption or impact of that phase of the product’s life cycle. Then the “low-low” quadrant indicates the most sustainable product. The “high-high” quadrant contains products that are to be avoided or, in another sense, offer the most potential for improvement. The two “high-low” quadrants represent products where we need either to increase the efficiency of the product (with respect to design or using manufacturing leveraging) or we need to improve the efficiency of the manufacturing process relative to use and manufacturing phases, respectively.

This figure does not, however, discuss the relative importance of all the phases of the product life referring back to the earlier discussion about the role of design. I’ve tried to capture this in the figure below. The figure shows the contribution to lifetime impact or energy/resource use of the various phases of a product, from first concept through design and production to end of life.

First, please note that this is a conceptual drawing (even a cartoon) trying to represent reality. There are lots of examples where this likely does not represent real product performance. And, you might be able to adjust the location of the high and low parts of a particular pattern relative to the phase somewhat as well. But, having said that, we can identify at least four patterns of impact shown in the figure as A. B, C, and D.

Pattern A, in blue, is what I think is a typical impact cycle with the major contributions to impact coming in the manufacturing and use phases. Pattern B, in red,  reflects design decisions that more aggressively affect product impact – things like inefficient use of energy based on design decisions/component selection, materials choice, etc. Pattern C, in yellow, reflects an introduced manufacturing process/system efficiency that reduces the manufacturing contribution but has little impact on the rest of the product performance. This might be due to a more efficient process chain for manufacturing.

Finally, pattern D, in green, represents an example of “leveraging” manufacturing. Here the assumption is that a more capable manufacturing process is introduced in the production plan that may consume more energy or resource in itself but offers product advantages in that it improves the performance of the product over its lifetime. The example given in an earlier posting about improvements in automobile engine efficiency due to aggressive use of precision manufacturing is in this category.

An important point to note is that it is the area under the curve that is the cumulative impact of the product – basically the product of impact x time. Meaning, Pattern D is the best in this example since the area under the line representing that pattern is the smallest of all the examples. The worst case illustrated here, in terms of cumulative impact, is pattern B – poor design decisions.

It is possible to have improved manufacturing offset, somewhat, poor design. Pattern C does that to some extent.

Think about these two figures and the decisions that can be made along the product phase from design through end of life that will have an effect on where the product is located in the use vs manufacturing space. There is a lot of potential for reducing the impact of the product.

And, you can tell from the way I’ve composed these examples that I come from the manufacturing side of the engineering profession! I don’t mean to “dis” my design friends in any way. I just want to make sure we are all aware of the tremendous potential manufacturing offers to address the sustainable consumption challenge.

We will continue to work on these “potentials” more in the future.

David Dornfeld is the Will C. Hall Family Chair in Engineering in Mechanical Engineering at University of California Berkeley. He leads the Laboratory for Manufacturing and Sustainability (LMAS), and he writes the Green Manufacturing blog.

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