Putting new energy use metrics to the test

New Buildings Institute (NBI) has developed the first ever set of plug load energy use metrics, aimed at allowing commercial building owners and managers to more easily gain insight into their buildings’ energy use and to become more energy efficient.

Earlier this year, PECI used the NBI metrics to assess plug load energy use at PECI headquarters in the First and Main building in downtown Portland, OR. The study, which informed an energy-saving campaign, resulted in an 18% kilowatt-hour (kWh) reduction of PECI’s plug load.

According to the Energy Information Agency, plug load – defined as electricity use by equipment that plugs into a building’s electrical outlets – is one of the fastest-growing sources of energy use in commercial buildings. In typical offices, 15 to 20% of energy use can be attributed to the plug load of computers, monitors, printers, desk lamps, telephones, etc. In buildings with HVAC and/or lighting systems that have been upgraded or improved to be more energy-efficient, plug load can reach as high as 50% of total energy use.

The intent of NBI’s new metrics is to set a benchmark for plug load energy use and make it easier for building owners and managers to spot opportunities to improve energy efficiency. The methodology allows an apples-to-apples comparison of plug load energy use across commercial buildings, even if they have vastly different plug load makeups and characteristics.

PECI helped NBI test the theories behind their metrics during a study conducted in the Portland offices of PECI. PECI’s LEED-Platinum office is equipped with an energy management system that allows circuit-level monitoring of energy use throughout the office space. This fact, coupled with PECI’s commitment to the study, practice and influence of responsible energy management, made the site – and the pairing – ideal.

NBI’s metrics showed that PECI’s plug load performance during business hours was already quite good, with numbers comparable to the metrics’ lowest reference value. Overnight, however, PECI’s plug load rated more poorly, with values above the metrics’ median.

“We discovered our higher overnight plug load was primarily due to people leaving their computers in ‘sleep mode’ when they left the office for the day,” said Joan Effinger, engineering manager at PECI.

[source: http://www.sustainableindustries.com/resources/peci-tests-latest-energy-use-metrics-new-building-institute]