How much energy do our Plug Loads actually use?

Written by: Marta Schantz

Recently, the Washington Post published an article titled, “This is why people are so clueless about how much energy they use,” which explained how people’s assumptions of energy usage does not always align with actual energy usage. While the title of the article is a bit harsh, the overall point is valid – often times building occupants have no idea what the large energy hogs are, and as a result their efforts to save energy may not result in as significant savings as expected. The Washington Post gives an example that home owners may not realize how much more energy their water heater uses than their dishwasher.


This applies all too directly to tenants in commercial buildings with their perception of plug and process loads (PPL). Prospective building occupants and real estate brokers typically lack accurate references for PPL capacity requirements. A recent NREL study found that while prospective tenants typically request 5-10 Watts/ft2, the true peak PPL energy use intensity (EUI) for offices with data centers is just a fraction of that at 0.88 W/SF. This difference highlights the disconnect between expected EUI and actual EUI. NREL also published a report on monitoring the energy end-use of healthcare equipment. Building engineers were surprised to find that the MRI machines and related equipment had a much lower EUIs than perceived. Instead, the highest overall energy users were Reheat and Heating (27% of site usage), and Lighting and Plug Loads (combined for 21% of site usage).


Speaking of plug loads, building engineers are often uncertain of how to assess and reduce them in commercial buildings. The almost cliché phrase in the energy world “you can’t measure what you don’t meter” applies here extremely well. For office buildings specifically, NREL outlined a useful step-by-step process for monitoring and controlling PPLs in this guidance document.


Waypoint supports the Department of Energy’s (DOE’s) Better Buildings Alliance on their PPL efforts, including an upcoming webinar on July 8th covering the DOE’s recently published Advanced Power Strips (APS) Technical Specification. APSs have the potential to significantly reduce plug loads in commercial buildings, but procuring the right type of APS for a building may be complicated. To simply the process, the APS tech specs help building owners define, procure, and use APSs in commercial buildings. The webinar will walk through the details of the specification, as well as provide examples of how stakeholders can apply the specification (e.g., for tenants in leased spaces, for building owners and managers, for utility incentive programming.). If you’re interested in learning more about leveraging APSs to meter and control your building’s plug loads, RSVP for the webinar here!