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Learn & Plan Topics

  • Plug Loads

    Plug loads refer to energy used by equipment that is plugged into an outlet. In an office, key plug loads include computer and monitors, printers...

  • Best Practices & Case Studies

    One of the best ways to learn and make the case for green building innovations is to point to others’ experience in implementing these innovat...
  • Building Plug Loads

    Plug loads can average approximately 30% of electricity use in office settings, much of which can be attributed to parasitic loads (power draw of a ...
  • Building Operations and Maintenance Services

    Follow these sustainable strategies as your space renovations are complete and the building and interiors are operated in an environmentally sustai...
  • Indoor Environmental Quality (IEQ)

    Indoor Environmental Quality (IEQ) is most simply described as the conditions inside the building. It includes air qualit...

  • Energy & Atmosphere

    Buildings and facilities rely on the operation of mechanical systems and electrical systems to maintain a high level of indoor environmenta...

  • Sustainable Sites

    Choosing a building's site and managing that site during construction are important to ensure a project’s sustainability. Environmentally r...

Plug Load Control

Plug load control comes in two basic forms. Energy savings are achieved when the device is either transitioned to a low-power state, or it is de-energized to eliminate the power draw. Both can be executed either manually or automatically. A low-power state is between a de-energized state and a ready-to-use state. This includes standby, sleep, and hibernate modes as well as any “off” state that has a parasitic power draw. A de-energized state is when electricity is not being provided to the device. This is analogous to physically unplugging a device’s power cord from a standard electrical outlet.

The most prevalent plug load contral strategies include:


Manual Control: Most plug-loads can be manually powered down with built-in power buttons, shutdown procedures, or a control device that energizes and de-energizes electrical outlets based only on manual input. The effectiveness of manual control depends entirely on user behavior and should be implemented only if no other methods apply.


Automatic Low-Power State: The first, and in some cases most effective, control method is a built-in, automatic low-power state functionality such as standby or sleep. Some manufacturers include this functionality to reduce energy consumption of idle devices. Internal processes monitor idle time, and when the device has been in an idle state for a given period, it will power down to a low-power state.


Schedule Timer Control Device: Certain plug-loads have predictable load profiles. These devices are used during the same times each day or at regular intervals. A scheduling-control device can effectively manage a predictable plug-load. It applies user-programmed schedules to de-energize the plug-load to match its use pattern and energize the plug-load so that it is ready for use at the time when it is required.


Load-Sensing Control Device: Plug loads may have a primary-secondary relationship. A primary device, such as a computer, operates independently of other (slave) devices. A secondary device, such as a monitor or other peripheral, depends on the operation of other (master) devices. A load-sensing control device should be implemented for such a relationship. It automatically energizes and de-energizes secondary devices based on the “sensed” power load of the primary device(s). Whenever the primary device goes into a power state below a given threshold, the load-sensing control can power down the secondary devices. The sensed (primary) load is typically an electrical outlet or an auxiliary port (e.g., universal serial bus (USB) in the case of a computer).


Occupancy-Control Device: Occupancy control can save a great deal of energy as it energizes plug-loads only when users are present and de-energizes them when the space is vacant. This approach pinpoints the main source of wasted energy during non-business hours and reduces wasted energy during business hours. However, the largest drawback is that occupancy controlled devices may energize and de-energize outlets at inappropriate times.


Manual-On, Vacancy-Off Control Device: A manual-on, vacancy-off control device is a slight modification of the occupancy-control device. It energizes a plug-load when it receives manual input from a user and de-energizes the plug-load automatically based on lack of occupancy. This control should be implemented for plug-loads that are needed only when users are present (e.g., task lights, monitors, and laptops).

Whole Building Systems

  • Submetering - Green Globes NC

    Is there sub-metering installed for the following systems: light and lighting controls by floor or by zones, plug loads by floor or by zone, major e...

  • IEQ - Lighting Control

    Incorporating task lights into the overall lighting strategy allows occupants to customize their ambient light conditions on a personalized basis. T...

  • IEQ - Moisture Control

    Moisture can enter the office building in a number of ways, including leaks in the building envelope and plumbing systems or excessive moisture in t...

  • Submetering - Human Behavior on System

    People’s behavior is a critical factor in a building’s energy use and can often account for significant changes in the amount of energy ...

Materials

  • Manual-On, Vacancy-Off Control Device

    A manual-on, vacancy-off control device is a slight modification of the occupancy-control device. It energizes a plug-load when it receives manual i...
  • Manual Control

    Most plug-loads can be manually powered down with built-in power buttons, shutdown procedures, or a control device that energizes and de-energizes e...
  • Load-Sensing Control Device

    Plug loads may have a primary-secondary relationship. A primary device, such as a computer, operates independently of other (slave) devices. A secon...
  • Schedule Timer Control Device

    Certain plug-loads have predictable load profiles. These devices are used during the same times each day or at regular intervals. A scheduling-contr...