With 40-hour-plus work weeks the norm and no signs of that trend reversing, seeing well in the office at any time of day or night is necessary to get the job done.
Illumination in the office can mean a combination of different types of light, artificial and natural. But the big story in lighting centers on new products and control systems that bring the discipline to the forefront of commercial integration. Just as heating, ventilating and air-conditioning (HVAC) has become one with building management and energy savings, lighting has stepped up to take its place as part of the integrated control environment.
It makes perfect sense. Most of a building’s energy costs come from the use of lighting. Statistics continue to show uncon-trolled lighting can raise the temperature inside the building and cause HVAC systems to operate more frequently. Lighting also has become closely tied to energy efficiency and the green building movement, epitomized in the Leadership in Energy and Environmental Design (LEED) program administered by the U.S. Green Building Council, Washington, D.C.
There are other drivers of widespread changes in lighting. Depending on the location and the type of facility, local or state energy codes may be mandated, and usage must be curbed inside and out—such as the case with the dark-sky initiatives, which are part of a movement to avoid the effects upward lighting has on the environment.
Up to the task
Lighting for commercial offices takes many different forms and performs multiple functions. The end application for deployed lighting is critical. Task areas require high illumination, both direct and indirect, but the amount of light, of course, depends on the nature of the business. Lighting should not interfere with computer screens by causing unwanted glare. Close work on production tables or other processing areas must illuminate clearly and evenly. Office areas with displays or showrooms need task lighting and illumination, which puts light on key areas of the facility.
Proper deployment of lighting is a science. The key performance characteristic of a light source is its output or lumen rat-ing. The intensity distribution or candle power also must be known, and many variables must be considered. Numerous re-sources are available to the electrical contractor (see box on page 92).
One study of task lighting in offices conducted by the National Research Council (NRC) Canada suggests office workers prefer to have light on all room surfaces, not just on their desks, which may be due to low levels of ambient lighting and high levels of task lighting, creating uncomfortable lighting conditions. According to NRC, it found no link between organizational productivity and vertical surface brightness. However, their studies have demonstrated that when lighting conditions differ from occupant preferences, there can be a negative impact on comfort and satisfaction.
Task or ambient light for office buildings has been a staple of design for many decades; fluorescent or metal halide use has been the primary components of these markets. They still hold their own, providing lighting integral to work spaces and buildings. But these disciplines have evolved into lamps, ballasts and controls that can save energy by being dimmable or being able to shut down quickly and return to service at a moment’s notice or within a preset time. A ballast supplies the ini-tial electricity that creates the light and then regulates the amount of electricity flowing through the appliance, so the lamp emits the right amount of light. Ballasts also are integral to the use of occupancy sensors, and instant-start types are not rec-ommended for use with these detectors.
New developments in fluorescent and high-intensity discharge (HID) ballast technology focus on improved system perform-ance, control capability for dimming, daylighting integration, energy management functions, and solutions to some long-standing problems that occur when certain lamps reach end of life, such as those containing mercury. The most energy-efficient fixtures, according to the American Council for an Energy Efficient Economy, are T8 or T5 fluorescent lamps, low-wattage and ceramic metal halide lamps, white LEDs or electronic ballasts.
According to Tom Leonard, director of marketing and product management, Leviton Lighting Management Systems, Tuala-tin, Ore., fluorescent lighting is still the unsung hero of efficiency.
“Fluorescent lighting is definitely not a ‘shop light’ anymore,” he said. “Users need to know that it’s not just cool white bulbs anymore. There’s a perception on the part of many that all fluorescents look like that. Fluorescent lighting provides high performance and a reasonable cost and a wide array of different tones,” he said. Because fluorescent lamps don’t use heat to create light, they are far more energy-efficient than incandescent bulbs. But how do they compare to LEDs?
“LEDs will become more cost-effective once efficiency targets are reached on a production scale and economies of scale are realized,” Leonard said.
“In office lighting, LEDs are the next advancement. Their high efficiency makes them perfect for task lighting,” he said. Continued production is needed for the price to drop to lower levels, Leonard said.
GE Consumer & Industrial, Cleveland, is working on a number of next-generation products, including white LEDs, which are near the illumination strength of incandescent and provide a true white light versus blue. They are smaller-than-ever T2 com-pact fluorescents and high efficiency incandescent lighting comparable to CFLs, which GE plans to roll out in 2009, accord-ing to Michael Petras, vice president of lighting and electrical distribution. In LEDs, there are downlight and cove light appli-cations, and these products will see more application in task operations, especially as their price tumbles.
Lighting, like many other solutions, is definitely driven by the use of the computer in the office environment.
“If it’s done right, you can direct lighting properly for the application,” Petras said. “There’s a lot of indirect lighting be-ing used with task and direct. There’s even task lighting built into office furniture. A key trend is that you don’t need to put everything in the ceiling to get the right lighting.” Another trend, he said, is the development of fixtures that produce more daylight-like light, such as ceramic metal halide.
Another growing trend in the area of commercial office building lighting is the use of lighting control subpanels, according to Scott Jordan, product marketing manager-lighting controls for Square D/Schneider Electric, Nashville. These panels can be installed in an out-of-the-way place, such as a ceiling.
Best of both worlds
“Outfitting a conference room or suite with a light-level sensor, for example, allows a lighting control subpanel to automati-cally dim lights to capitalize on available natural light. Plus, using lighting control subpanels can reduce cost for wire/conduit and can make labor easier for a contractor by being able to run circuits to the subpanel and not all the way back to the panelboard.”
Jordan said another trend is load shedding. Load shedding, he said, is a concept where selected electrical loads, including lighting, in a commercial building are reduced during various times of a day because of a desire to save energy or due to a utility request.
“For example, lighting can be dimmed a certain percentage during times when traffic is lighter, thus reducing energy costs. In more extreme circumstances, the local power utility may demand that a building owner/facility manager reduce loads due to a strain on the power grid and the possibility of a brownout or blackout.
“Multiple technologies are appropriate to achieve load shedding for commercial buildings,” he said. “Whole-building, sched-ule-based lighting control system that are Web-enabled provide perhaps the best opportunity to dim or turn off selected lighting loads because a facility manager is able to access the lighting control system via a common Web browser, no matter the time of day or week. Occupancy sensors can also play a significant role in load shedding due to the ability to automatically turn off lights in non-essential areas when no one is present.”
Lighting is critical in office environments, but the real challenge is controlling it to raise energy efficiency while giving the user options in its operation. Innovation by manufacturers continues to provide the right product that performs in an effi-cient manner and meets the application end use. EC
O’MARA is the president of DLO Communications in Park Ridge, Ill., specializing in low-voltage. She can be reached at 847.384.1916 or firstname.lastname@example.org.