Buildings consume around 75 percent of electric energy in the United States while producing around 28 percent of carbon emissions. Responsive trends such as energy efficiency, control, demand response, renewable energy, electric vehicles, and battery energy storage are often implemented independently.
The U.S. Department of Energy (DOE) is now promoting grid-interactive efficient buildings (GEBs) that unite these trends to produce clean, efficient, and demand-flexible buildings, citing potential savings for the U.S. power system of up to $200 billion and CO2 emission reductions of up to 80 million tons per year by 2030.
In A National Roadmap for Grid-Interactive Efficient Buildings, DOE outlines its national goal to triple the energy efficiency and demand flexibility of buildings by 2030. A subsequent report, published in December 2019, specifically evaluates the potential for lighting and electronics (primarily consumer plus IT equipment) to optimize energy efficiency and comfort while providing services back to the grid.
This article examines lighting’s potential to support grid interactivity, primarily in the form of networked lighting controls and automated demand response.
Lighting and ADR
Demand response is a reduction in demand for power to shave demand peaks and reduce stress on the power grid during emergency events. By better matching power supply and demand, cost savings and greater reliability of power can result.
Demand response may be passive, achieved via energy efficiency improvements that reduce load, or active, achieved via reducing load during peak demand periods (economic demand response) or emergency grid events (emergency demand response). So that the load reduction is predictable and reliable, power providers may seek agreements with customers—typically the largest power users—where they offer economic incentives to curb a certain amount of load upon request. This may be automatically triggered via a signal, called automated demand response (ADR).
How does lighting fit into this?
By 2018, efficiency trends in lighting reduced its share of commercial building energy consumption from about 40 percent to 16 percent overall and 18 percent during the peak demand period (2PM to 8PM), according to DOE. LED lighting significantly reduces energy consumption, while advanced sensors and controls can add 20 to 80 percent energy savings depending on the application, according to research by the DesignLights Consortium. Arguably, when it comes to passive demand response, energy-efficient lighting and advanced controls are already accomplishing heavy lifting, with plenty more lifting to do in the existing buildings market and by integrating lighting control with plug load and HVAC control.
The DOE report looks beyond lighting energy efficiency to evaluate potential grid services used to enact active demand response:
Load shedding: ability to reduce load for a period of time, typically during peak demand periods and emergency grid events.
Load shifting: ability to change the timing of electric energy consumption, which helps balance demand.
Load modulation: ability to balance the supply and demand of power automatically and virtually instantaneously via signaling from the grid operator.
Of these, DOE identified load shedding and fast load modulation as emerging opportunities for managing demand and in particular demand peaks with lighting. Load shedding was rated as a “medium” capability (suitable but limited capacity) and load modulation as a “low” capability (possible but not well suited). Load shifting is not really applicable, as lighting’s overall commercial peak (8AM and 5PM) and residential peak (6PM to 10PM) correspond with hours when users need light for comfort, productivity, and safety.
Because the lighting system must be able to respond globally, a building-level networked lighting control system may be considered foundational for ADR, one that is capable of receiving and acting upon the external ADR signal. Because lighting is essential for productivity and safety, the lighting system typically will respond via dimming, now a fairly staple capability of LED lighting, rather than turning loads Off.
Incorporating lighting into ADR has several potential advantages. Theoretically, the ADR signal is just another input for the networked lighting control system, and with sufficient demand, manufacturer solutions can be configured for it using a standard interface. And research suggests a majority of users are likely to accept some level of dimming without considering it disruptive, though DOE suggests more research to evaluate dimming impacts in different contexts.
There are some challenges, however, notably the limits on the dimming control effect and the size of the controlled load—hence load shedding being only a “medium” capability. In some lighting designs, such as task-ambient LED lighting systems, there is little room to dim the general lighting. As a result, the ADR industry has focused on HVAC and industrial loads, where it typically gets bigger bang for the buck.
Image courtesy of the Department of Energy.
Currently, penetration of grid-responsive lighting is very low in the commercial sector (and virtually nonexistent in the residential sector), primarily limited to networked lighting control systems enacting dimming in mainly large buildings, though smaller buildings may benefit via a demand aggregator. Of these buildings, many are in California and built to the 2016+ versions of the Title 24, Part 6 energy code, which required new buildings >10,000 sq.ft. be capable of automatic wattage of reduction of 15 percent in response to a demand response signal. As a result, relatively few lighting systems are equipped with demand response features such as OpenADR Alliance standard compliance.
Connected lighting systems with advanced sensors and controls currently account for a small fraction of the installed lighting base but are expected to grow rapidly over the next two decades. By 2035, DOE projects that one-third of lighting in the commercial sector will be connected, driven by energy codes, utility rebates, energy savings, and non-energy benefits driven by data and analytic capabilities.
As the market for building-level networked lighting controls develops along with interest and support for ADR, the two may become increasingly connected to realize an opportunity that today is largely untapped. The bigger, more immediate opportunity, however, is with passive demand response—adoption of LED lighting and networked lighting control systems that maximize energy efficiency.
Click here to check out the DOE report.