Smart Control Strategies for Lighting and Plug Load
Advances in lighting technologies coupled with building code requirements have resulted in a sharp decline in the amount of electricity used for lighting commercial buildings. Despite that success, there is still room for substantial improvement. The most recent report by the Commercial Buildings Energy Consumption Survey (CBECS), says that lighting still accounts for 17% of all electricity consumed in U.S. commercial buildings.
So after moving away from incandescent, halogen and fluorescent lighting sources, what else can be done to cut energy usage even further? Implementing an automated light management system that also controls plug loads can dramatically increase energy savings.
Let’s take a look at some smart control strategies for lighting and plug load that will help you significantly boost your energy efficiency while improving occupant comfort.
We are all familiar with the benefits of natural daylight. It improves productivity, creativity and even mood as well as decreases stress. Daylight is reported to be the number one natural element wanted in a workplace. Consequently, natural light is frequently incorporated into building design and leveraging that investment is a smart approach to lighting.
Daylight harvesting uses daylight to offset the amount of artificial light used in a space. As daylight levels vary, individual fixtures or zones can be programmed to dim up or down so that the illumination is maintained evenly at the desired level throughout the space. With a software-controlled lighting system, adjustments can be subtle and the energy saving potential significant.
Task tuning is when lights are dimmed to create a suitable level of light for a particular task or activity conducted in a space. This strategy works best when spaces are occupied and can be adjusted based on occupant feedback. Because commercial spaces are often over-lit, task tuning can save energy without sacrificing occupant comfort and satisfaction.
Personal lighting controls allow the occupant to dim or brighten the lights in an individual’s specific area to their preferred lighting level. An individual may favor brighter or dimmer light levels than a coworker doing the same task and this control strategy enables them to tailor lighting to their personally desired level. Studies indicate that often individuals prefer significantly lower levels of light than recommended practice levels resulting in a reduction in energy consumption as well.
Typically employed in spaces with intermittent and unpredictable usage such as corridors, stairwells, storage areas and parking garages, occupant sensors are proven to dramatically reduce lighting usage and energy consumption. Lights are programmed to either “dim” or “switch” in response to an occupancy status signal from a sensor. This control strategy also adds improved comfort for occupants as they never have to enter a dark area or manually turn lights ON/OFF in areas where sensors are installed.
To save energy in spaces that have predictable occupancy and daylight patterns like factories, lobbies and open office spaces, automated time scheduling should be considered. Lights in zones as small as a workstation or even a luminaire can be turned “ON”, “OFF” or “DIMMED” depending on day, night, holiday and other programmed schedules.
Variable Load Shedding
Electricity charges have both a consumption (kilowatt-hours consumed in a typical month) and demand (kilowatts consumed during peak usage period) component for commercial buildings. During peak periods when costs are highest, variable load shedding selectively dims lights per a programmed percentage automatically with minimal disruption to the occupants of the building. This control strategy provides a cost effective measure as less power is drawn from the utilities when electricity costs are the highest.
Plug Load Control
Plug load, also known as receptacle load, refers to energy loads that are not related to lighting, heating, ventilation, cooling and water heating. It is the energy used by devices that typically plug into an ordinary AC outlet such as computers, printers and data servers. The New Buildings Institute reports that plug loads are one of the fastest growing sources of energy use in commercial buildings today and account for 15-20% of office electricity use.
By integrating plug loads into your lighting control system, time scheduling and/or occupancy control strategies can be leveraged to automatically turn off plug loads at a specific time or when a space is vacated.
Most commercial buildings have multiple uses with occupants performing different tasks and activities in a range of workspaces. For maximum energy efficiency and optimum occupant comfort, a combination of control strategies should be applied simultaneously.