Lighting Research Center

Advancing the effective use of light for society and the environment

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Volume 3 Number 3
Copyright @1998 Rensselaer Polytechnic Institute

The quest for the
ideal office control system

Images of flickering fluorescent tubes humming loudly overhead have long been used by advertisers and Hollywood producers as symbols of inhospitable workplaces and uncaring management.

The entertainment industry knows that these images imply that business owners are willing to subject workers to bad lighting in order to save money. Receptive audiences respond to these tales because they believe that bad lighting can cause migraines, eye strain, and fatigue.

Four Views on Ideal Controls

The Lighting Research Center co-sponsored a round table on lighting controls in December 1997 with Lawrence Berkeley National Laboratories. Participants included end-users, manufacturers, industry groups, government organizations, and researchers. Recently, Lighting Futures asked several of the participants a few questions about the ideal office system.

Wayne Morrow | Maria Vargas
Dave Peterson | Jerry Mix

Today's bottom-line oriented managers, however, are slowly beginning to realize that providing good lighting for workers is good for business. Electricity for lighting typically accounts for less than 5 percent of business overhead, and employee salaries and benefits are far more expensive, so when energy savings plans ignore the worker, the effort may be counterproductive.

In recent years, the lighting industry has introduced new technologies to try to save energy without negatively affecting occupants. "By substituting lower wattage technologies without adversely affecting light levels, distributions, and spectral qualities, building managers have a high probability of avoiding occupant complaints," says Dr. Mark S. Rea, director of the Lighting Research Center (LRC), "and they look like heroes by reducing operational costs."

According to the United States Environmental Protection Agency (U.S. EPA), lower wattage technologies include T8 lamps, which are more efficacious than conventional T12 lamps used in most buildings, and high-frequency electronic ballasts, which require 12 to 25 percent less energy than their magnetic predecessors. In 1996, sales of T8 lamps were four times higher than in 1992, and T8s accounted for 21 percent of all fluorescent lamps sold.

Rea believes that installing T8 lamps and electronic ballasts are a safe but unambitious strategy because they do nothing to improve light levels or reduce wasted energy. In addition to using lower wattage technologies, building managers can add benefits by installing lighting controls.

Maria Vargas, co-director of the ENERGY STAR and Green Lights Partnership at the U.S. EPA, agrees with Rea. "Organizations are looking for ways to not only cut costs, but also to improve productivity," says Vargas, "Increasingly that is being linked to giving the occupant a measure of control over their environment."

Hollywood images of spartan workplaces capitalize on the lack of control office workers have over existing systems. "It's very well understood and documented that you have to give people a sense of control over their environment," says Wayne Morrow, facility electrical engineer at the National Center for Atmospheric Research (NCAR) and author of several papers in building systems theory. "Without a sense of control, they will rebel or enter a state of 'learned helplessness' - they give up and stay mad.

"Personal control has to be a choice, even if it's not used. The right system allows the user to control the environment, but doesn't require it. Requiring the user to constantly make adjustments is like having a waiter at a restaurant who keeps interrupting your conversation to ask if everything is okay. You just want him to go away and quit bothering you."

After listening to focus groups of NCAR employees, Morrow overhauled the facility's entire lighting system in 1991, and he has continued to install new equipment to meet the demands of the occupants. At present, the facility has occupancy sensors, manually operated window blinds, and manual dimmers at both the wall and the desk. Additionally, the lighting and heating, ventilation, and air conditioning (HVAC) are monitored using a Building Automation System (BAS).

The NCAR facility was made available to the LRC to investigate the use of manual lighting controls on occupant behavior, energy savings, and occupant preferences. The incorporation of all these manual controls with a means to monitor their use allowed the first comprehensive look at modern occupant-responsive technologies. "Lighting controls have undergone major changes in the past 25 years," explains Dorene Maniccia, manager of Lighting Applications at the LRC, who led the investigation at NCAR. "After the energy crisis in the 1970s, controls became independent of the occupant on the theory that automatic systems guaranteed energy savings. With a manual system, nobody knew if anyone used it, and you couldn't tell if you were saving energy. But the savings from automatic systems were believed to exist. One of the goals of the research at NCAR was to answer questions about whether man-ual systems are used, save energy, and are liked by occupants."

The answers are yes, yes, and yes. Most occupants use manual controls, and doing so saves energy. And as an added benefit, the occupants valued having the manual controls.

At NCAR occupants' routines were monitored in 58 offices for 8 weeks using data from the BAS as well as observations of window blind use, occupant tasks, and weather conditions. Seventy-four percent of the occupants used their dimmers at least once. On average, while occupants were in the offices, the lights were dimmed 28 percent of the time and were off 24 percent of the time (see figure 1).

The amount of time the lights were at each light setting during occupancy varied according to the office location. On the north side of the building, people kept the lights off 57 percent of the time they were using the office. Not surprisingly, occupants of interior offices kept their lights off just 3 percent of the time. However, the use of dimming was widespread, except on the east side. Occupants in the interior had the lights dimmed 32 percent of the time and those on the north dimmed 24 percent of the time.

The NCAR study also revealed how occupants use window blinds (see figure 2). On the south and west, occupants adjusted their blinds to keep out the direct sunlight. On the south, the blinds were always closed, and the slats were adjusted to block sunlight. On the west, the blinds were closed in the afternoon, particularly on clear days, with slats again adjusted to block the sunlight. In both cases, the slats were adjusted so that the occupant could still have a view to the outside. On the north and east sides, however, occupants rarely closed their window blinds.

Because the occupants on the south and west had their blinds closed much of the time, it makes sense that their light use patterns are similar to those of occupants of interior offices. They seldom have the lights off -16 percent of the time on the south and 14 percent of the time on the west- but they often have the lights dimmed, 37 percent of the time on both the south and the west.

Lighting controls at NCAR accounted for 61 percent energy savings, compared to a 10-hr lights on-full scenario. Occupancy sensors (automatic off and automatic dim) saved 46 percent, turning off the lights saved 9 percent, and dimming saved 6 percent (see figure 3).

The controls in the interior offices produced a 55 percent energy savings - 48 percent from occupancy sensors, 1 percent from having lights off, and 6 percent from dimming, again compared to the 10-hr lights on scenario.

The location of a dimming control at the desk also had a dramatic impact. Occupants were one-third as likely to dim when the desk dimmer was removed, and 60 percent of occupants preferred having the control near their workstation. Forty-six percent preferred having the control at their desk near the keyboard, 8 percent liked having the control attached to the computer monitor, and 6 percent preferred other locations on the desktop that were hidden from view, like behind a photograph.

When asked why they adjusted their lights, occupants did not mention energy. Instead, they mentioned tasks, such as working on the computer or reading and writing, and compensating for lack of daylight (see figure 4).

"One of the most important benefits of the manual controls," explains Maniccia, "is that the occupants like and use them. Occupants placed a high value on the ability to dim their lights, and as evidenced from the study, most people use them when given the opportunity."

The combination of an occupancy sensor with manual controls was a resounding success at NCAR, but this type of system is not found in most facilities.

At present, many office lighting systems are holdovers from the 1970s. Although T8 lamps and electronic ballasts are beginning to be introduced into the market, occupant-responsive lighting controls are not.

Many in the industry agree that it is a problem of educating the consumer. But Rea believes that the problem is more complicated. He says that a bias towards precision leads decision makers to reject strategies that use statistics to accurately predict energy savings over space, time or weather. "Part of our effort is to understand why controls aren't being installed now. Our customers tell us that they've had bad experiences in the past, they're confused about their choices, and they don't understand the potential of using these technologies," Vargas says.

For their part, manufacturers have been redesigning controls to increase reliability. "Electronics have made dramatic improvements in the past five years," says Jerry Mix, president of The Watt Stopper, a controls manufacturer. "Across the industry we're seeing microprocessors and ASIC (Application Specific Integrated Circuits) improve the function of occupancy sensors. We're using active IR (infrared) to communicate between different controls, allowing wireless remote controls."

Using controls that have active IR offers more than just added convenience because the cost of labor for wiring each control to a wall switch is eliminated. Both Watt Stopper and Mytech have occupancy sensors that are located at the desktop, where, according to Mix, "There are no more false-offs. It can't miss the person when the sensor is right at the desk. And using active IR, it also allows integration with other building systems such as dimming ballasts and heating and air conditioning. Once you get it, you're hooked."

Integration with other systems is an essential aspect to the future of building systems, including lighting. David Peterson, chairman of the National Electrical Manufacturers Association Council on Lighting Controls, foresees integration as one of the driving forces of making these systems more acceptable to owners. "Building owners will integrate occupant-responsive controls with other intelligence within the building - HVAC and security - to share hardware costs and to centrally monitor the building.

They can tell when a lamp has failed, or a ballast, or an occupancy sensor. Ideally, this would be fixed before an occupant even realizes it has happened."

Peterson says, "From a technological standpoint, the major obstacle to be overcome is the integration of these different components into standardized packages - to create systems which plug and play. It's an implementation problem. The technology exists today in each component, but not for creating integrated systems from those components."

Morrow agrees with Peterson, with the expectation that integration will also result in better facilities management. "The big thing that's happening is that we're moving away from geographical boundaries. In the past, facilities have been limited by the need to have someone on site. Management was a manual process accomplished by on-site personnel. The systems at NCAR are managed from a facility that's 15 miles away. That trend will continue. It's going to get to the point where you can see what's happening better if you are not there. We haven't gotten there yet, though."

The research into controls, and technology advancements such as active IR, clearly demonstrate that occupant-responsive lighting controls should be installed with new lighting systems in private offices. The advantages of T8 lamps and electronic ballasts can be multiplied with the installation of these controls, not just in energy savings but also in occupant satisfaction. Who knows, in another ten years, Hollywood may be looking to lighting as a symbol of benevolent management.

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