Detailed Energy Data Collection for Miscellaneous and Electronic Loads in a Commercial Office Building

Miscellaneous and electronic loads (MELs) consume about 20% of the primary energy used in U.S. buildings, and this share is projected to increase for the foreseeable future. Our understanding, however, of which devices are most responsible for this energy use is still rudimentary. Developing efficiency strategies for these products depends on collecting data that describes their diversity and varied usage patterns. Few studies have collected field data on the long-term energy use of MELs, due to the difficulty and expense of traditional power meters. Recent advances in wireless technology, applied to power meters, provide a relatively inexpensive metering method and allow for large-scale, long time-series data collection. In order to cost-effectively generate representative MELs energy data for future studies, this study addressed the following important methodological questions in a typical office building: 1) How much of the building floor area should be inventoried, 2) What fraction of the inventoried devices should be metered, 3) How long should these devices be metered, and 4) At what sampling intervals should power data be collected? We performed a full MELs inventory in an 89,500 square-foot office building and subsequently deployed a total of 455 wireless power meters on sampled devices, for periods of 6-16 months. We concluded that in the study building, performing a device inventory for 25% to 30% of the floor area and metering 10% to 20% of the inventoried devices from key device categories, for a period of two months, would have generated meaningful and accurate data to inform MELs energy use.