Study Demonstrates Worker Performance Impact of Personal Lighting Control

By Craig DiLouie, Lighting Controls Association

New landmark research study conducted by the Light Right Consortium indicates that personal control of lighting not only saves energy, but can result in a significant improvement in employee satisfaction and motivation. Confirming previous studies indicating a causal link between personal control and performance, the study is an important step in validating the impact that quality lighting -- in particular personal control -- can have on how people perform in the workplace.

The Light Right Consortium Explores Lighting-Performance Link

The Light Right Consortium's goal is to transform the lighting market by using research to investigate the link between lighting quality and the performance, satisfaction and productivity of workers. The Consortium's recently completed landmark study confirmed previous research that indicated there is a causal relationship between personal control of lighting and worker satisfaction and performance. Before we discuss the study, it is important to understand its context -- the market transformation effort as a whole.

The Consortium, formed in 1998, is managed by the Pacific Northwest National Laboratory and operated by Battelle for the U.S. Department of Energy. Board members include the Alliance to Save Energy, the Illuminating Engineering Society of North America, the International Association of Lighting Designers, the International Facility Managers Association, Johnson Controls, the National Electrical Manufacturers Association, the New York State Energy Research and Development Authority, Steelcase, the U.S. Department of Energy and the U.S. Environmental Protection Agency.

The market transformation project was designed to be implemented in three phases:

Phase I:  Research to determine market attitudes and behavior

Phase II:  Laboratory and field research to test hypothetical link between various types of lighting and occupant satisfaction and performance

Phase III:  Development of tools to implement quality lighting concepts in the market

"Central to the success of the Consortium is establishment of a link, based on sound research results, between quality lighting and economic benefits," said Carol C. Jones, LC, Program Manager. "Market transformation goals include 1) influencing customer decisions so that they are designing, purchasing and installing higher-quality and more energy-efficient technologies, 2) going beyond the technology issues to delve into the dynamic of customer and market behaviors, and 3) creating enduring market changes."

Phase I involved market research to provide proof of concept. A survey was conducted among professionals who specify, install and own/use lighting systems. It was not surprising that 87 percent of respondents reported flexibility in lighting budgets if a return on investment could be demonstrated. But 75 percent said if factual evidence indicating a positive effect by lighting on worker productivity was available, it would influence which lighting systems they would buy. These results validated the need for Phase II, which was to provide this factual evidence validated by scientific method, and to study which lighting approaches were the most effective at influencing workers.

The Landmark Study

With Phase II's implementation, a research program was formulated to address the question, "Can different forms of realistic office lighting affect the performance of office work or the well-being of employees?" The primary variables included room surface brightness and personal control. The results are still being compiled related to the effects of room surface brightness and will be announced in August at the IESNA Annual Conference. The results are complete for personal control, however, and they are quite extraordinary. The study indicated that personal dimming control resulted in occupants performing better on certain productivity metrics.

How Controls Save Energy

An office in Albany, NY was set up as a typical space for nine workers. The open office plan featured perimeter windows and access to a view, although translucent window shades were used to alleviate the impact of daylight at workstations. The space was planned and furnished to allow the researchers to change the lighting between five different lighting systems without the knowledge of the subjects. The workers were temporaries hired to work under the different lighting conditions for a typical eight-hour day. A range of output measures were collected that ranged from the subjective (occupant opinion) to objective (quantitative performance), resulting in a large data set. The study was conducted in the field, but with simulated tasks and a degree of experimental control. This approach was chosen to maximize realism and the validity of the research.

The four lighting scenarios included:

"Best Practice" :  Linear system of direct/indirect fixtures together with wall-washing to brighten the walls.

"Switching Control" :  The same as best practice but with a moveable desk lamp having three manually switched light outputs and providing some individual control.

"Dimming Control" :  Direct/Indirect fixtures suspended over the center of each cube, together with wall-washing system. The direct component of each could be dimmed using the interface on the occupant's computer.

"Parabolic Base Case" :  Regular array of three-lamp parabolic-louvered fixtures.

The Light Right Consortium is also analyzing a lensed-troffer base case, with results available later this year and marking the completion of this study.

Project sponsors who contributed equipment included Armstrong, Birchwood Lighting, Cooper Lighting, Day-Brite Lighting, Engineered Lighting Product, General Electric, Ledalite, Lightolier, Lutron, OSRAM SYLVANIA, Peerless Lighting and Philips Lighting. The Lighting Research Center and the National Research Council of Canada were contracted to perform the research.

The temporaries worked for a complete day on set tasks to simulate elements of office work, and on questionnaires linked to the productivity metrics being studied.

When asked whether they agreed with the following statements at the end of the day, the workers responded:

"Overall, the lighting is comfortable."

"The lighting is uncomfortably bright for the tasks that I perform."

These questions were part of the subjective part of the study and represent within-subject-comparison results; complete results and greater detail will be available when the final study research findings are presented at the IESNA Conference in August.

Personal dimming control with linear suspended direct/indirect fixtures yielded a 30-point spread in response to whether the workers believed the lighting was comfortable, and produced the lowest incidence of workers perceiving their lighting to be uncomfortably bright for the tasks they performed.

In the objective segment of the research, the Light Right Consortium discovered that the presence of control had a measurable impact on motivation, which in turn was represented in the study in measures of persistence and vigilance. Persistence at a difficult or impossible task is an indicator of motivation at the task; people who are not motivated to do the task will not continue at it when it becomes very difficult. Vigilance is a state of watchfulness or careful attention, and is related to accuracy. The study subjects were more able to sustain their persistence and vigilance over the day in the personal dimming scenario compared to the baseline and best practice conditions. The probable reasons for this included:

•  The ability to fine-tune the lighting conditions to meet the needs of individuals, both with respect to horizontal light levels and the brightness on the surrounding partitions.
•  The ability to satisfy the preferences of individuals -- the function of satisfaction in the workplace.
•  The psychological impact of control on motivation.

"Perhaps the simplest and most profound message with respect to personal control is that we are learning that personal control significantly improves our ability to optimize the satisfaction and performance of office workers," said Jones. "We know from prior work conducted at National Research Council of Canada that it there is a great variety of preferred light levels. This tells us that we have a tremendous opportunity, and a tremendous challenge, if we choose to raise the bar with respect to meeting the needs of the office worker population."

A. J. Glaser, president of the Lighting Controls Association and HUNT Dimming, said, "The Lighting Controls Association applauds the Light Right Consortium's market transformation goals and results. As HUNT Dimming was involved in the original Lighting Research Center study at NCAR, our company, like most manufacturers of controls, have known for years that personal control can save energy while supporting the owner's goals of encouraging workers to be more satisfied and perform better in the workplace. This study validates the original research and will benefit owners of lighting systems, the people who use them each day to work, and the lighting industry as a whole. The Light Right Consortium's efforts have already begun to change the way America is lighted for the better, and we look forward to further study."

The First Research

The Light Right Consortium's results confirm previous studies, which indicated that occupants were responsive to controlling their own lighting. The first major research in this area, conducted by the Lighting Research Center, demonstrated manual dimming energy savings of six percent in its eight-week study of 58 private offices at the National Center for Atmospheric Research (NCAR), a three-building, 250,000 sq.ft. complex in Boulder, CO. Each office was lighted with two 2x4 recessed troffers housing three 32W T8 lamps driven by dimmable electronic ballasts. The lighting controls included a wall-mounted manual unit for on-off and dimming; a portable manual dimmer on the desktop; and a PIR occupancy sensor mounted in a corner for automatic switching.

The Lighting Research Center reported energy savings of 61 percent, with 43 percent from occupancy sensors, six percent from manual dimming, and the rest from other methods. Seventy-five percent of the occupants used the manual dimmers at least once and used the desktop dimmer over the wall-mounted unit by a ratio of six to one. The occupants also used their manual controls to switch the lights.

The biggest reason they dimmed their lights? Computers, they said. "Compensation for daylight," "read printed text," and "create an atmosphere for work" were other important reasons to 10-20 percent of the survey participants. Whatever their specific reasons, the Lighting Research Center concluded, "Employees … prefer manual lighting control to automatic controls because the manual controls allow them to tailor the lighting to their needs."

Completing the Transformation

Jones said the next step for the Light Right Consortium is to continue experimentation in a full field study, after which the results can be used to implement Phase III -- developing tools to effect enduring market transformation. These tools will include lighting analysis software that integrates potential productivity benefits with energy savings to create a life-cycle cost analysis for various lighting approaches being considered for projects.

While the results validating the utility of personal lighting control are important, it is also significant to note that a causal link between how a space is lighted and worker satisfaction/performance is being established that goes beyond simply providing enough light on a workspace for a worker to see and do a task. For many years, lighting professionals have argued that lighting has a larger role to play in productivity, the central principle being that light is for seeing, while lighting is for perception.

There is now solid evidence, beyond the intuitive and anecdotal, forming to support the statement, "Personal lighting control can have a positive impact on worker satisfaction and performance in addition to generating energy savings."

Personal Control: Product Solutions

Below are a few product solutions from members of the Lighting Controls Association, which enable facility operators to capture the benefits of personal control.

winDIM@net software by Tridonic
www.tridonic.com

Tridonic offers winDIM@net computer control software package to support PCA DALI digital ballasts in central and individual occupant lighting control applications. The system is installed on an existing computer network and the software leverages standard web based applications. The system features include individual occupant control of assigned fixtures, standard lighting control functions, logging of fixture operating levels (energy consumption calculation), and reporting of lamp and ballast failures. The package is a perfect solution for every installation, from a small office to large or multiple buildings where individual user control is desired, or where detailed management of the installation is required.

HUNT Dimming Systems
www.huntdimming.com

HUNT manufactures a broad line of dimming devices for individual control of personal spaces. Products range from Digital Dimming Systems available with LCD Touchscreen or multi-button control stations and I/R remote, which provide simplicity and flexibility to even the most demanding applications; to a complete line of 0-10 VDC, Phase-Control, and DALI-based wallbox dimmers for use with dimmable electronic fluorescent ballasts. HUNT Dimming is also an EPA affiliated ENERGY STAR Partner.

Lutron PerSONNA Dimming System
www.lutron.com

With the PerSONNA Dimming System from Lutron Electronics Co., Inc., each worker has personal control of the overhead fluorescent lighting in his or her own area. Using a hand-held remote control, workers can dim or brighten the light depending on the task, the time of day, or their individual needs and preferences -- all at the touch of a button. PerSONNA reduces glare, eyestrain and fatigue to improve productivity. The PerSONNA system's direct control of overhead fluorescent lighting not only improves working conditions, it also saves energy consumption since lights are usually operated at less than 100% output.

Leviton Centura™ Lighting Control System
www.leviton.com

The Centura system combines personal lighting control with daylight harvesting, occupancy sensing and advanced energy management software to provide improved worker satisfaction and high energy efficiency.

By enabling desktop lighting control, users can set and adjust their lighting preferences as they work on their PC. Additionally, wall-mounted controls permit full-range dimming as well as on/off control. Handheld remotes complete the system, putting personal control in easy reach, regardless of room or space configuration.

Advanced management software permits administrators to view current light settings, occupancy, and schedule LIGHTS-OFF cycles. By combining all these technologies, Centura provides unifies energy conservation technologies with personal control, for an efficient, productive facility.

Lightolier Multiset Pro™
www.lolcontrols.com

The MultiSet Pro™ system of wallbox dimmers and master keypads from Lightolier Controls provides flexible 13-scene dimming capability. The system was designed and engineered to be easy to install, program and operate. MultiSet Pro's powerful 8-bit processor responds immediately to scene selection signals from the 13-scene Master. Up to 30 devices (dimmers, masters) can be incorporated into a single system. MultiSet Pro's MSP dimmers are ideal for low wattage loads in residences and small conference rooms. MHP series dimmers are great for high wattage applications (up to 2000 watts per dimmer) found in restaurants, class rooms, conference rooms, churches and commercial spaces. Dimming amplifiers are available for control of larger loads (up to 12,000 watts per channel). MultiSet Pro is not phase sensitive. Additional masters can be easily installed anywhere. All dimmers can be raised or lowered simultaneously at any master keypad. Any MultiSet Pro dimmer can have one or more corresponding full function remotes.

ULTRAWATT Energy Systems’ PowerGate Sensor
www.ultrawatt.com

This single lighting controller functions as an occupancy sensor, mounted on the ceiling or wall, that also dims using a handheld remote control. The remote control also displays the reduction percentage. The Sensor is ideal for private offices, conference rooms, classrooms and other medium to large switched lighting loads. Adjustable from a minimum of 10% energy reduction and a maximum of 30% while the lights are on, with additional energy savings derived from use of the occupancy sensor. Dimming occurs gradually over a period of about five seconds.

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