A Tale of Two Tiers: Advanced Power Strips in Commercial Buildings

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by
Marta Schantz, Waypoint Building Group; Sormeh Konjkav Waypoint Building Group; Rois Langner, NREL
on
Jan 03, 2017

Chances are the commercial building you work in or manage consumes excess energy by drawing power from appliances when not in use. In fact, the General Services Administration estimates that 25% of commercial plug load electricity is lost to these “phantom” loads.  An easy solution to reduce phantom loads is to purchase and install Advanced Power Strips (APS). These APS technologies look just like traditional power strips, except they have built-in features designed to save energy.

If you’ve already begun looking into procuring APSs for your organization, you may have noticed that there are two primary types of advanced power strips: Tier 1 and Tier 2. They both operate on the same basic principle of shutting off supply power to devices that are not in use. But there are differences between the two, and its important to know which one is best for you and your needs.

Tier 1:

Tier 1 APSs turn off and disconnect power to appliances after a master device is powered down. For example, a Tier 1 APS will automatically turn off peripheral devices (such as monitors, printers, and task lights) when your computer is in sleep mode or turned off. Generally, APSs have three types of outlets depending on usability needs. Primary outlets are for master devices, such as computers or TVs that other devices are dependent on. Secondary outlets are for peripheral devices that can operate dependently on the master device, such as monitors, printers, or task lights, and are turned off when the master device is powered down. APSs also have “always-on” outlets that are never turned off for equipment such as telephones or refrigerators that need to stay on all the time.

In the simplest terms, Tier 1 APSs provide simple master-switch control, delegating one outlet to a master device and automatically switching off peripheral devices when the master device is powered down. Current retail prices for master controlled Tier 1s range from $30 to $60 and have been able to achieve plug load savings of 26% at workstations with advanced computer management already in place, and 50% in kitchens and printer rooms.  

Tier 2:

Tier 2 APSs operate differently. Tier 2 APSs go a step beyond using advanced sensing capabilities to disconnect power to devices that are idle, in addition to master-switch control capabilities. The advanced sensing capabilities monitor background computer processes to track inactivity or lack of engagement, offering an additional level of savings compared to Tier 1s.

Originally, Tier 2 APSs were developed to sense infrared signals from remote controls to cut power to residential home entertainment systems, after sensing user inactivity over a predetermined period of time. This way, power is not wasted after residents fall asleep or leave the house without turning off the TV. Nowadays, Tier 2s are also made for commercial office workstations. After sensing inactivity at a workstation, the Tier 2 de-energizes peripheral devices and puts computers into a low-power standby mode rather than a complete shutdown to avoid data interruptions. Thus, if an occupant leaves their desk for a meeting, the Tier 2 APS will sense inactivity after a set period of time and de-energize all peripheral devices and put the computer into standby. Additionally, Tier 2s come with software that alerts users prior to shutdowns, allowing for shutdown overrides. Retail prices for Tier 2s range from about $70 to $100 and can achieve average plug load energy savings of 65% at office workstations.

How to Choose the Right Tier for Your Organization’s Needs:

Three important factors to consider when choosing an APS tier are the organization’s current energy use and equipment, the organization’s energy savings goals, and budget for the energy savings measure. The two-tiered decision also depends on the type of control that staff are willing to incorporate into their daily behaviors. Tier 1 APSs may be more applicable for users who remain at their workstations for extended periods of time, and those that turn off or disconnect their master device at the end of the day. Tier 2 APSs may be more suited for busier users like managers who tend to have multiple meetings and are away from their computers many times a day. In the end, it depends on preference and specific use cases.

Whether or not you’ve read A Tale of Two Cities by Charles Dickens, at least now you know the Tale of Two Tiers by the DOE Plug and Process Loads Technology Solutions Team. Visit the Better Buildings Solution Center for additional resources on APS technologies and guidance on how to manage plug and process loads in your commercial buildings.