Energy and Cost Savings in Plug Loads

Mike Bailey

Last month I had the opportunity to present at two different events about Ecova’s research into plug load energy use in commercial buildings. It was encouraging to see such interest in this often over looked driver of building utility spend. While plug loads are often just listed as “other uses” in most buildings, the US Energy Information Administration predicts that plug load energy intensity will continue to increase through 2035, while both HVAC and lighting energy intensity are expected to decrease (total national commercial use by lighting and HVAC are expected to grow slower than the growth of total commercial sq-ft space). The full EIA 2012 report can be found here.

The first event I spoke at was the Getting to Zero Forum, held as part of National Association of State Energy Officials (NASEO) annual Meeting in Denver, Colorado. The Forum was organized to share information between building architects and engineers on issues related to achieving the goal Net Zero Energy use for new commercial buildings by 2030. It was refreshing to see so much interest in how buildings are actually USED! There was broad recognition that building designers need to pay much more attention to HOW building occupants use energy if buildings are to achieve the Net Zero goal (buildings are able to “power themselves” by producing all needed energy on-site, thus being zero net energy consumers).

My presentation focused on commercial plug loads research Ecova performed with the New Buildings Institute that was funded by the California Utility Commission’s Public Interest Energy Research (PIER) Program. The study collected data usage from over 100 devices at two separate sites for over a month. The study was conducted at two new LEED Certified buildings, so most of the equipment monitored was also relatively new. It wasn’t much of a surprise to learn that most plug load usage was driven by computers and the powered peripherals that come in the modern office―what was surprising was how infrequently most of this equipment was actually used and how much power continues to be consumed at night and weekends. There are many opportunities for energy cost savings―possibly as high as 95% (hint: see slide 18 in my presentation and an Ecova case study. A summary of the findings and recommendations of the PIER Plug Load study can be accessed here.

My second presentation was targeted to building operators at the Building Operator Certification (BOC) continuous education quarterly training webinar. The BOC program is a great effort to educate and certify building staff on how buildings use energy, and I’m happy to see their interest in plug loads! Plug loads are a challenge for building operators because achieving energy savings requires operators to work closely with building occupants―hardware fixes ALONE don’t work!

In both presentations, I focused on office plug loads common in almost every commercial facility. Unfortunately, I did not have time to discuss the other often over-looked type of plug loads―servers and other IT infrastructure (“server closets” and small data centers).  While taking up little physical space these can be HUGE electrical users (see slide 26 of my presentation  for an example of where computer equipment occupied less than 0.8% of a 350,000 sq-ft office building but used over 20% of its electricity!). The good news is that there are opportunities for large energy savings in data centers and servers, but I’ll have to save that for another post.

Plug loads use a surprising amount of energy in our buildings and have often been grouped as “other” uses and considered unmanageable. The good news is that plug loads are very manageable and large savings are possible. Effective plug load management requires holistic approaches―to reduce plug load energy use, building designers, owners, occupants, and operators all need to work together. That is why I was so encouraged to see both designers and operators interested in the topic at my presentations!

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