Before this century, building occupants typically gave little thought to the amount of electricity consumed by lighting. But now the rising cost of energy, along with the implementation of stricter building codes, has brought energy conservation measures in lighting into sharper focus.
In 2011, lighting in the commercial sector, which includes building and roadway illumination, accounted for 21 percent of all electricity consumed—a total of 275 billion kilowatt-hours.
Efforts to conserve lighting energy are being made on several fronts. Regulations are requiring the use of higher-efficiency light sources. For instance, building codes in California, which historically leads the nation in environmental health and safety standards, mandate energy-efficient lighting fixtures and design strategies under Title 24, which went into effect in 2011. And a new generation of digital, wireless, and computer-operated lighting controls has enabled a greater degree of energy management than ever before.
The first federal lighting-efficiency standards were introduced in the 2008 Energy Independence and Security Act. These standards, which phase in from 2012 to 2014, require than lamps sold for light fixtures use 25 to 80 percent less energy than incandescent bulbs of the same light output. The 2012 International Energy Conservation Code (IECC) also requires that 75 percent of the lamps in fixtures installed in new construction and renovation projects be "high efficacy," or produce a high amount of luminance per unit of electrical power consumer, typically expressed as lumens per watt. High-efficacy fixtures have nonreplaceable lamps or are designed to accept only high-efficacy lamps such as light-emitting diodes (LEDs).
In California, where interior and exterior lighting systems account for an estimated 25 percent of total energy use, new commercial and residential building-permit regulations under Title 24: Building and Energy Efficiency Standards mandate the installation of energy-saving, high-efficacy fixtures, or luminaires. The standard allows builders to include low-efficacy fixtures in specific situations, but only if paired with energy-saving lighting controls. Title 24 became law in 2008 and went into effect in 2010; a major revision, which includes the mandate of multi-level and on-off lighting controls in commercial buildings, becomes effective Jan. 1, 2014.
“We’re doing better at conserving energy on the building envelope, but in order to do better overall, we’ve got to address lighting,” says Dennis Creech, executive director of the Southface Energy Institute, an energy-efficiency research and development center in Atlanta. “A few years ago, I wouldn’t have been excited about lighting controls, but now that the technology is there, it’s workable.”
Today’s lighting controls reflect the rapidly increasing sophistication of electronic devices in general. The analog timers and manually operated rheostat dimmers of the past have given way to computer-controlled luminaires, multiple-zone occupancy and vacancy sensors, photocell daylight sensors, programmable lighting scenarios, and other innovations that add new levels of occupant convenience and security while decreasing energy consumption.
Much of the hardware has been available for years. The addition of digital circuitry, Wi-Fi-enabled operation, and computer software allow for the control and coordination of systems far beyond the simple on–off functions of the past.
Dimmer controls, for example, can be automated by using daylight and occupancy sensors to adjust interior or exterior lighting as per the user needs or as the amount of available natural light changes. Lighting also can be linked to a building’s heating and ventilation system to keep pace with temperature fluctuations. Electrochromic glazing on windows, which transforms from clear to nearly opaque to reduce solar heat gain and glare, adds yet another layer of control. In a similar way, multilevel lighting fixtures that automatically adjust their output levels as residents come and go, or as required by emergencies, can be placed in areas that experience irregular occupancy, such as corridors, stairwells, and outdoor parking lots.
Energy-management systems add a higher level of operational control. These computer-based, multifunctional programs regulate and coordinate lighting fixtures, HVAC equipment, security systems, and other electronic equipment through high-capacity (i.e., Category 5e) wiring or wireless devices. Wi-Fi-enabled systems can be accessed through smartphones and tablet controllers using readily available apps or custom dashboard software programs, through which users can view and manage not only the controlled devices, but also the electricity they consume. Users can then remotely adjust lighting, schedule dimming or shutoff times to reduce power draw, and create energy-saving strategies and scenarios to suit day-to-day occupant activity.
In an integrated lighting system, these controls can significantly reduce a building’s overall energy load. Simply dimming the lighting by 25 percent—using a network of motion and daylight sensors, bi-level lighting fixtures, and a programmable control system—can save an estimated 5 percent of a building’s total energy cost, according to Vantage Controls, an Orem, Utah–based manufacturer.
Lights Out—or Rather, Dimmed
Lighting consultant Michael Gehring, FAIA, partner and CEO of Kaplan Gehring McCarroll Architectural Lighting in El Segundo, Calif., says that specifying lighting controls is similar to choosing other architectural features. “We start with performance specifications,” he says. “We’ll write in features that the lighting controls have to conform to, and then we’ll go to the manufacturers and have them bid on it.”
Despite the broad range of products and the requirements of building standards, such as California’s Title 24, saving energy with lighting controls is not always a client’s priority. “Owners like all the options, but they don’t always want it,” Gehring says. “Even though it saves money over time, there’s a big first cost. So we start with the ‘Cadillac’ plan and show them all the things they can do, and then work down.”
One workaround to the complexity and costs under Title 24, Gehring says, is to control all fixtures with dimming strategies. The code’s complex rules, which are generally aimed at limiting overall lighting energy usage, are generally based on “when all of the wattage is turned on all the way,” he says. Subsequently, dimming controls and self-dimming fixtures are two of the easiest ways to address it. “When the code changes in January,” he adds, “pretty much everything will be dimmed.”
New energy-efficient, “high-benefit” lighting devices and controls are competitive in cost with lower-performing fixtures, according to the National Lighting Bureau (NLB), a nonprofit energy-awareness coalition of trade associations, manufacturers, utilities, and federal agencies. Any initial cost premium due to installation, programming, and purchasing is more than offset by the reduction in energy use over time, NLB states. High-benefit lighting, particularly when scaled up in commercial settings, also offers additional advantages, such as enhanced safety and security, reduced liability and insurance costs, and increased productivity and occupant enjoyment.
The potential savings of lighting energy control in multifamily, high-rise, and commercial buildings are immense. Through these electronic controls and remote monitoring, real estate and facility management companies can now regulate lighting in buildings occupied by thousands of transient and residential users to maximize savings and reduce waste, prevent outages during peak load periods, and manage demand to reduce consumer energy costs. All from the touch of a few buttons.
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