Plug Load Inventory
Within Stanford’s large and diverse building portfolio, there are tens of thousands of pieces of equipment plugged into wall outlets. Many suspected the aggregate plug load from this equipment would represent a substantial component of electricity demand on campus. To better quantify electricity consumption and prioritize savings opportunities, Stanford launched an equipment inventory to collect data on plug loads across the Stanford campus. An article summarizing the project and its results was recently published in Energy Efficiency.
During spring and summer 2014, 12 trained Stanford student interns utilized an internally-developed smart phone/tablet application to collect inventory data throughout 220 main campus buildings, totaling nearly 9 million square feet of building space. Due to the success of this initial inventory effort, an expanded equipment inventory was conducted in Summer 2015, covering 43 additional on- and off-campus buildings. The expanded inventory allowed Stanford to develop a more complete picture of plug loads on campus, especially by including student residences. Ultimately, the equipment inventory not only provided operations staff with crucial plug load data, but it also increased the visibility of sustainability initiatives across campus.
In addition to tracking 55 types of electronic equipment, interns also recorded data on water fixtures, occupancy, environmental safety measures and motion sensors. Nearly 240,000 pieces of equipment were identified across the 20,000 rooms that were inventoried. In total, the electricity consumed by this equipment amounts to approximately 35% of Stanford’s total electricity consumption and costs $9 million per year.
Plug Load Energy Reduction Pilot Program in DAPER
In 2016, the Office of Sustainability partnered with the Department of Athletics, Physical Education and Recreation (DAPER) and Keewi Inc. to install smart plugs at workstations throughout three of Stanford’s recreation buildings. The smart plugs collect high resolution energy data at each outlet, and Keewi’s mobile app empowers users to more easily control their plug loads by setting schedules and remotely powering their devices on and off. The app also continually engages individuals through fun activities like questions of the day, competition, and incentives for reaching various levels of energy savings.
More than 100 plug load sensors were deployed in the three pilot buildings on equipment such as printers and scanners, laptop and desktop computers, monitors, TVs, water coolers and coffee makers. After a month of baseline data collection, occupants were asked to download the mobile app and begin their energy conservation efforts. The buildings engaged in friendly competition with one another for who could reduce their plug load energy consumption the most; altogether, the participants achieved an overall average plug load savings at their work stations of 21%! As part of this pilot, DAPER staff have not only been able to reduce their energy footprint, but they’ve also gained valuable energy conservation and sustainability knowledge that they can continue to apply into the future. For more information, reference the white paper on this project.
Data from the equipment inventory in summer 2015 suggests that there are over 75,000 pieces of electronic equipment within student residences on Stanford’s campus, which comes out to about six electronic devices per student living on campus. Altogether, this equipment is estimated to consume 11.3 million kWh per year, which emits the same amount of greenhouse gas as more than 1,600 passenger vehicles.
Refrigerators were found to be one of the biggest “energy hogs” in every type of student residence. In dorms, personal refrigerators located in students’ bedrooms are the highest energy consuming type of equipment. With an estimated 3,000 personal refrigerators in dorms across campus, the university could save over $1 million dollars by facilitating the use of common refrigerators and avoiding this additional electricity cost.
On the other hand, student residences comprise about 15% of the university’s total plug load electricity consumption but actually equate to nearly one third of the university’s building footprint, so focusing on reducing consumption in academic buildings—and especially lab buildings—will be key to campus-wide plug load reduction.
Academic, School of Medicine, and Recreation Buildings
Office of Sustainability staff analyzed the inventory data within academic buildings to identify the biggest “energy hogs” and determine the most effective plug load reduction programs moving forward. Of the 10 types of equipment with the highest electricity consumption, five were types of lab equipment, three were types of networking equipment, and two were types of office equipment. The two types of office equipment with the highest consumption were personal computers and space heaters. Overall, lab equipment is expected to consume 39% of total plug load energy consumption, with IT equipment (servers, network switches, and uninterruptible power supplies) slightly lower than lab equipment at 29% of total consumption.
The equipment inventory data was also analyzed at the building level to help reveal the best approach to plug load reduction strategies. The building-level analysis showed that the 10 buildings with the highest plug load energy consumption consume approximately 55% of Stanford’s total plug load consumption. This illustrates that a targeted building-level approach to plug load reduction could also be effective.
Of the 93 plug load reduction program options identified as a result of the equipment inventory, 11 programs have been launched or expanded and several others are in development. If all viable programs are implemented, a potential annual savings of $2.3 million in electricity costs could be achieved. All plug load reduction opportunities are being administered through the Energy Retrofit Program, the Sustainable IT program, and the Green Labs program on campus and are highlighted in the annual Cardinal Green Buildings campaign.
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