PUE for end users - Are you interested in more than bread toasting?

The Power Usage Effectiveness (PUE) indicator for efficiency of data center infrastructure has been very successful. But focusing solely on PUE tends to restrict action to data center infrastructure management and in some situations even gives a perverse stimulus against optimization at the IT equipment and software levels. Despite the high relevance, no accepted metric has emerged to support optimization and allow the rating of the energy efficiency of the whole stack. This paper presents a metric, the Consumption Near Sweetspot (CNS), that for a part can fill this gap. It captures how well the system-relative energy efficiency optimum and its utilization are aligned. A strong point is, that it allows a comparison of functionally very different services. The metric is compared to the Fixed to Variable Energy Ratio (FVER) metric for data centers recently proposed by the British Computer Society.