The relationship between manufacturing efficiency and energy productivity is poorly understood (Papadaratsakis, 2007). Most manufacturers assume that increasing productivity means increasing energy usage at about the same energy intensity (EI) level. Others believe there is a volume effect with increased production and EI goes down only to discover that it rises. This paper will investigate the relationship between these components using a model presented at the 2009 ACEEE conference to measure energy savings through process improvements in manufacturing plants (La Palme, 2007). The model offers energy efficiency calculations for whole building, prescriptive measures, or regression analysis. Five examples of varying operating conditions will be presented from a thermoforming plant in Southern California. The first is the baseline model. The second will show changes in energy intensity when there is a decrease in manufacturing output with no increase in production time. The third will analyze the same plant with an increase in manufacturing output with a similar increase in production time. The fourth example will demonstrate variation in product demand. This example creates great EI measurement difficulties and is common to all plants. The fifth will be an increase in output with no increase in production time through improvements in manufacturing efficiency based on system optimization (Church, 2005). Changes in manufacturing operations alter energy intensity and how these affect energy productivity will be analyzed. Finally, what tradeoffs should plants consider planning on certifying under the soon-to-be-released ISO 50001 taking the Plant Energy Intensity pathway?
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