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CATEGORY: Topics » Occupancy Sensors
By Lighting Controls Association, on March 20, 2012
The National Electrical Manufacturers Association (NEMA) has published NEMA WD 7 Occupancy Motion Sensors Standard.
Previously published as a guide and not a standard, WD 7 promotes uniformity for the definition and measurement of characteristics relevant to the use and application of occupancy motion sensors. This standard covers the definition and measurement of field of view and coverage characteristics relevant to the use and application of vacancy and occupancy sensors using individual or any combination of passive infrared, ultrasonic, or microwave technology. These sensors are used in systems for control of lighting, heating, ventilating, and air conditioning (HVAC), and other devices.
WD 7 may be downloaded at no cost here.
By Craig DiLouie, on February 17, 2012
Stairwells account for about 2% of multistory commercial building floorspace, with an average of one light fixture for each 58 sq.ft. of stairwell, according to the International Facility Management Association. It is trafficked 3-5% of the average day.
This application has emerged as a strong potential opportunity for energy-saving controls. In the near future, in fact, using energy-saving controls in this space will become standard practice due to commercial building energy code requirements.
Although the average stairwell is occupied infrequently and for short periods of time, many building codes require constant illumination for safety.
The Life Safety Code (NFPA 101) requires at least 10 footcandles of light on the stair tread while in use (Section 7.8.1.3). The use of automatic motion sensors is recognized as long as they provide fail-safe operation, turn the lights on upon occupancy, and keep the lights ON for at least 15 minutes after the space becomes unoccupied (Section 7.8.1.2.2).
Lutron Electronics, Lithonia, Philips Day-Brite, Philips Lightolier, LaMar Lighting and Columbia Lighting and other manufacturers now offer stairwell light fixtures with a dimming or switching controller, allowing energy savings to be captured in this application. The fixture operates at a constant low light level (energy-saving mode)—e.g., about 1 footcandle. When an integral or separately mounted occupancy sensor detects that a person has entered the space, it signals the controller to raise light level to code-compliant full brightness (occupied mode)—e.g., 10 footcandles. Some products provide complete shutoff capability for when codes allow it.
 Image courtesy of LaMar Lighting. The result is up to 70-80% energy savings, say manufacturers. The energy savings may have two components: first, the existing fixture may be T12 and replaced with a more-efficient electronic-ballasted T8, T5 or T5HO (or LED) fixture. And second, the occupancy sensor ensures the lights maintain a lower light level during the majority of the time the stairwell is unoccupied.
A 2003 Lighting Research Center study in two new York City buildings demonstrated 53-60% energy savings using this approach. A later Lawrence Berkeley National Laboratory study in four California buildings demonstrated 40-60% energy savings. And a Pacific Gas & Electric study at The Fillmore Center in San Francisco demonstrated 66% energy savings.
Stairwell fixtures are available in various lamp lengths and wattages; white or clear prismatic lens; and wall or ceiling mounting. The controller may offer step dimming (single ballast), continuous dimming (single ballast) or bilevel switching (two ballasts) capability, with a choice of low-end light level. The occupancy sensor is either mounted as a part of the fixture or separately with wireless communication between the sensor and the controller, and detects occupancy via passive-infrared (PIR) or ultrasonic technology. Adjustable time delay and emergency battery backup options are typically available. Some products contain a light sensor that maintains the low light level setting during occupancy if there is a high enough light level on the stairs due to daylight contribution from windows and skylights.
The challenge is to ensure that the lights raise to full output during occupancy, a function of avoiding sensor “blind spots” and ensuring the sensor is sensitive enough to raise light output immediately upon occupancy. If using a PIR sensor, note that the sensor must have a line of sight between the sensor and the occupant, and is most sensitive to people moving laterally in front of the sensor. Ultrasonic sensors are more sensitive, do not require a line of sight, and are most sensitive to people moving to and from the sensor. Wireless sensors enable more flexibility in placement, as they are not tied to a specific fixture location.
The Lutron PowPak Stairwell Fixture, for example, uses a Lutron digital continuous dimming ballast preprogrammed to occupied and unoccupied levels, while offering field programming. The fixture receives signals from Lutron’s Radio Powr Savr wireless occupancy sensors via the company’s Clear Connect radio-frequency technology. In this solution, the wireless sensor provides flexibility in placement, ensuring adequate coverage. It raises light level not only for the fixture in the immediate area, but also the floor above and the floor below, providing a relatively seamless experience for the occupant.
 Image courtesy of Lutron Electronics. Energy code standards are beginning to mandate this approach. Section 9.4.1.6(g) of the ASHRAE/IES 90.1-2010 energy standard—the minimum standard for all commercial building energy codes by October 18, 2013 per Department of Energy ruling—lighting in stairwells must “have one or more control devices to automatically reduce lighting power in any one controlled zone by at least 50% within 30 minutes of all occupants leaving that controlled zone.”
Bilevel stairwell lighting offers a simple method of saving energy in new construction and retrofit applications.
By Lighting Controls Association, on February 3, 2012
High bay lighting controls represent a significant opportunity to cut overall energy consumption. Learn more about how they can increase energy savings and reduce wasted energy consumption by downloading a free whitepaper, High Bay Occupancy Sensors: Delivering Energy Savings and Fast Return on Investment, from Sensor Switch free here (PDF).
By Lighting Controls Association, on November 16, 2011
 The Lighting Controls Association is pleased to announce that it has updated Section 1: Occupancy Sensors of EE102: Switching Controls, a popular offering in the Association’s Education Express series of online distance education courses about lighting controls.
The course, authored by Craig DiLouie, principal of ZING Communications, Inc. and LCA’s Education Director, provides an in-depth discussion of occupancy sensor technology and application. It consists of two learning modules covering these topics:
Technology
• Typical energy savings in various applications
• Operating modes (auto-ON to 100%, auto-ON to 50%, manual ON)
• Detection methods (PIR, ultrasonic, PIR/ultrasonic, PIR/acoustic)
• Power (low voltage, line voltage, wireless)
• Coverage area and pattern
• Mounting packages (ceiling, high wall/corner, wall switch, luminaire mounting, workstation)
• Features and special features
• Light loggers
Application
• Energy code requirements related to occupancy sensors
• Design process
• Typical applications for occupancy sensors
• Major sensor variables
• Choosing the right technology: PIR vs. ultrasonic
• Special applications: stairwell, workstation, emergency lighting
• Switching and lamp life
• Switching and startup
• Coverage area
• Mounting configuration
• Sensor placement
At the conclusion of each learning module, an optional online comprehension test is available, with automatic grading; a passing grade (70+%) enables the student to claim education credit.
Section 1: Occupancy Sensors of EE102: Switching Controls is registered with the National Council on Quality in the Lighting Professions (NCQLP), which recognizes a total of 4 LEUs towards maintenance of Lighting Certified (LC) certification. This course is also registered with the California Advanced Lighting Control Training Program (CALCTP) for credit to qualify to receive live training (20 points).
By Lighting Controls Association, on June 27, 2011
The National Electrical Manufacturers Association (NEMA) has published NEMA 410-2011 Performance Testing for Lighting Controls and Switching Devices with Electronic Drivers and Discharge Ballasts. This standard, last published in 2004, is maintained by the association’s Lamp, Ballast, Lighting Controls, and Wiring Device sections.
NEMA 410 provides guidance for the design and testing of lighting controls and switching devices to be used with electronic drivers, discharge ballasts, and self-ballasted lamps to assist in establishing and verifying compatibility between products. This standard has been expanded to encompass additional types of lighting technology, and numerous figures and test circuit diagrams and designs have been added.
Ed Thomas of GE Lighting, chair of the Ballast Section Technical Committee, said, “NEMA 410 is the industry standard for electronic ballast inrush current. This revision extends its applicability to include self-ballasted compact fluorescent lamps and integrated LED lamps, and NEMA encourages the standard’s use by those evaluating and designing electronic ballasts and device drivers.”
NEMA 410 may be downloaded free here. To find other NEMA lighting standards, click here.
By Lighting Controls Association, on January 21, 2011
 It’s well-known that automatic shut off of lighting in large commercial buildings helps facility managers and building owners save energy and money. State energy codes mandate the use of control panels or occupancy sensors in new buildings for this purpose. According to the U.S. Environmental Protection Agency (EPA), Lighting Research Center (LRC) and California Energy Commission (CEC) publications, energy savings from using such devices can range from:
- 17-29% in Break Room
- 36-52% in Classroom
- 22-65% in Conference Room
- 25-50% in Private Office
- 30-75% in Restroom
While automatic shut-off provides increased savings for customers, research suggests implementing advanced strategies available with manual controls like switches can really turbocharge both energy savings and return on investment. For instance, the 2008 California Lighting Technology (CLTC) study indicates that both Manual-On and bi-level switching with automatic on of 50% of lighting offer dramatic increases in energy savings. Combining both automatic shut off and manual on control strategies results in up to 52% additional savings when compared to just one control strategy. Researchers found that the best practice control scenario is to have one light level come on automatically based on occupancy, while the other remains off unless manually activated.
ASHRAE Standard 90.1-2010 recognizes the value of these findings in its latest version, by mandating the following requirement: “Any automatic control device shall either be manual on or shall be controlled to automatically turn the lighting on to not more than 50% power, except in the following spaces where full Automatic-on is allowed:
* Public corridors and stairwells
* Restrooms
* Primary building entrance areas and lobbies and
* Areas where manual-on operation would endanger the safety or security of the room or building occupant(s)
Manual-On operation has a huge potential for saving energy and these savings help gain LEED points for better energy performance.
By Craig DiLouie, on May 23, 2009
Originally published in the June 2008 issue of TED Magazine
 Acuity Brands Lighting, the parent of Lithonia Lighting, installed the company’s I-Beam fluorescent hi-bay fixtures with sensors in one of its warehouses, generating significant energy cost savings. Retrofitting standard metal halide hi-bay fixtures to fluorescent hi-bay fixtures can generate energy cost savings of about 50 percent. How does reducing the resulting energy consumption by another 30+ percent sound—made possible by switching to fluorescent?
While tapping what remains arguably the hottest lighting retrofit market, distributors should understand the full advantages of fluorescent over probe-start metal halide, such instant-on and re-strike, which enables the use of switching strategies typically not practical with HID light sources.
Example: An occupancy sensor installed in each fixture senses a lack of occupancy in the area, or a photosensor senses high light levels due to daylight contribution, and either switches off the fixture or its outboard lamp. This provides a choice of energy savings and, if desired, flexible selection of light levels.
An additional 30-80 percent energy savings using occupancy sensors and 10-30 percent savings using daylighting controls can be achieved in a hi-bay fluorescent upgrade, says John Ireland, OEM channel manager for Watt Stopper/Legrand.
Mike Connolly, market development manager for Lithonia Lighting – Industrial Products, says inboard/outboard switching—achieved by separating circuiting ballasts within the same fixture, enabling 0/50/100 percent and 0/33/66/100 percent lamp output/power—is an inexpensive way to gain the benefits of flexibility from the lighting system. “For example, in a gym, light levels can be lowered for school productions or other needs outside of athletics,” he says. “Multi-lamp fluorescent fixtures offer many light level possibilities for user control, daylight harvesting and other applications.”
Occupancy sensing is the predominant strategy, particularly in applications such as distribution centers, warehouses and bulk storage areas. “Any area of 50 percent or less usage levels will accelerate the project’s payback period—even with relatively modest electric rates of $0.07 per kWh,” says Connolly. To optimize lamp life, particularly when the fixtures have high switching activity—more than six on/off cycles per day—programmed-start ballasts and a minimum 15-minute sensor time delay are recommended.
Passive-infrared (PIR) technology is standard in occupancy sensors used in hi-bay applications. “Besides its low cost, most spaces in hi-bay applications are within the line of sight of the sensor, large motion is usually being detected, and little adjustment is required after installation,” says Tom Leonard, director, marketing and product management for Leviton Lighting Management Systems. In hi-bay applications, the sensor may have a lens that provides 360-degree coverage for open areas or a narrow linear coverage for warehouse aisles.
Traditionally, control in such spaces were configured into zones for occupancy sensor or time-of-day scheduling, requiring external power packs and low-voltage wiring. Following market preference for low-cost control solutions, occupancy sensor manufacturers such as Watt Stopper/Legrand, Leviton and Sensor Switch began offering line-voltage occupancy sensors. These sensors mount directly onto light fixtures, sold either through the fixture OEM as an integral component or purchased as a separate item and field-installed by the contractor.
“This enables the lamps in the fixture to be controlled by the sensor, and no additional control wiring is needed for ganging together fixtures into control zones,” says Ireland. “As a result, integral sensors reduce installation time and material costs. This makes for a faster return on investment on your projects, while also reducing the use of additional resources like copper wire. This is a more practical and sustainable approach.”
With no control wiring, these sensors are positioned as a natural for retrofit applications—included in the fixtures being sold into a current project, or sold as an additional upgrade into previous projects that did not include controls. By installing one sensor per fixture, layout and application are greatly simplified, says Leonard, and there are no zoning or re-zoning concerns, as each fixture becomes an individually controlled source.
He adds: “For the distributor, fixture-mounted hi-bay sensors require the least amount of technical value-added services and have some of the highest potential volume opportunities. The opportunity is huge, the technical and engineering support required is minimal, and many utilities are subsidizing their installation.”
Connolly also points out that individual sensors eliminate external controls hardware, making the fixture a self-contained lighting and control system that is more responsive to actual usage. “For example, if a forklift only goes a quarter of the way down an aisle, the other fixtures remain off, providing significant savings,” he says.
The highly granular degree of control, which each fixture responding individually to local conditions, presents interesting possibilities for daylight harvesting in applications receiving significant daylight contribution from apertures such as skylights. (In new construction projects in California, the state’s Title 24-2005 energy code requires daylighting controls in certain big-box spaces.) Ireland says while mounting a photosensor in each fixture is a simple, low-cost solution, it isn’t best practice: “The best way to accomplish daylighting control in a hi-bay application is to have daylighting control zones that match the daylight distribution; this typically results in using one photosensor in the skylight to control multiple fixtures as best practice.”
Leonard points out that an integral photosensor’s true utility within a hi-bay fluorescent fixture may not be actively turning the lights on and off, but working with the occupancy sensor: “The most common photosensor application included in hi-bay fixtures is a hold-off-type system incorporated within the occupancy sensor that prevents it from activating the fixture when adequate ambient light is available,” he says.
To understand the energy savings potential, a distributor need only look at its own warehouse facilities to see firsthand how often the lighting is operated in unoccupied spaces. But what about occupant acceptance? Are fixtures individually activating as workers move down a warehouse aisle likely to be accepted by the occupants, particularly if they are driving vehicles like forklifts?
Connolly says that in the end, seeing is believing, recommending that distributors take advantage of trial installation programs offered by manufacturers.
“Your customer is not looking to buy product, he is looking for a lighting system with better-quality lighting that uses less energy,” he says. “Find a contractor or service provider that you can build a relationship with to look for and address these opportunities. Offer your customers total turnkey solutions and you will add value beyond your competitors and discourage getting shopped out based on materials costs alone.”
By Craig DiLouie, on April 9, 2009
While the basic ON/OFF switch is not considered an energy-saving lighting control, it can be if at least two switches are used to control lighting in a space that is configured on two lighting circuits, giving the user a choice of two levels of light output.
Alternate rows, fixtures or lamps can be switched, offering a choice of 50% and 100% light output. Or the center lamps can be switched separately from the outer lamps in three-lamp fixtures, offering a choice of 33%, 66% and 100% light output. In one study by ADM Associates, the latter option was demonstrated to produce 22% energy savings in private offices.
At least one-half of the energy codes in the United States are based on the International Energy Conservation Code (IECC), which requires light level reduction controls such as multilevel switching or dimming in enclosed spaces such as private offices.
Occupancy sensors are just as simple—a switch married with a sensor to enable automatic switching based on whether the sensor detects the presence or absence of people. Occupancy sensing is a reliable method for generating energy savings: According to the Advanced Lighting Guidelines, occupancy sensors in private offices can produce up to 45% energy savings.
All energy codes require that general lighting be automatically turned OFF when it’s not used. Further, IECC says that if an occupancy sensor is used in an enclosed space such as a private office, light level reduction controls are not needed, suggesting an either/or choice.
What if bilevel switching was combined with occupancy sensor functionality? Would this produce higher energy savings in a private office than bilevel switching or occupancy sensing alone. And: What combination of manual initiative and automation would produce the highest energy savings while also satisfying workers?
 Typical office used in the study. The California Lighting Technology Center (CLTC) organized a study in eight private offices at the University of California – Davis in 2008 to attempt to generate useful data related to these questions. Each office, between 90 and 140 sq.ft. with a ceiling height of 9 ft., is lighted by a combination of indirect/direct pendant fixtures and daylight entering through a window with manually adjustable vertical blinds. The study was sponsored by Watt Stopper/Legrand.
“The baseline comparison,” researchers Theresa Pistochini, Judy Xu and Rahul Shira wrote in a report on the study, “is made to a theoretical case where the occupant has no control over their lighting and it is switched ON and OFF by an occupancy sensor.”
In the test offices, the pendants are configured with dual circuiting, with a ballast driving two lamps (48W) placed on each circuit. This enabled the researchers to set up three test conditions and record data on occupancy.
 Office at 50% light level. • Auto-ON to 100%: When the office became occupied, an occupancy sensor signaled both relays to automatically turn the lights ON to 100% light level. If the occupant wanted a lower light level, they can flick a switch to 50% or manual-OFF. When the occupant left the office, the sensor then automatically swept the lights OFF.
• Auto-ON to 50%: When the office became occupied, the sensor signaled one relay to automatically turn one-half of the lamps ON to achieve 50% light level. The user could flick a switch to increase light level to 100% or turn the lights OFF. When the occupant left the office, the sensor then automatically swept the lights OFF.
• Manual-ON to 50% or 100%: When the office became occupied, the sensor did not turn the lights ON. Instead, the user could turn the lights ON to 50% or 100% light level, or leave them OFF. When the occupant left the office, the sensor then automatically swept the lights OFF.
 The bilevel switching occupancy sensor. “Occupants were informed about the manner in which the electric lights would behave and also that they were participating in a lighting controls study,” the study’s authors write. “However, the occupants were specifically not told that the purpose of the study was to measure the impact of their behavior on energy consumption.”
All three scenarios saved energy compared to the baseline scenario, suggesting that combining bilevel switching and occupancy sensing saves more energy than using an occupancy sensor alone. Specifically:
• The auto-ON to 100% bilevel occupancy sensor saved 34% compared to the baseline.
• The auto-ON to 50% bilevel occupancy sensor saved 52% compared to the baseline.
• The manual-ON bilevel occupancy sensor saved 46% compared to the baseline.
“This is quite impressive given that the designed lighting power density in the offices was already quite low at 0.7 to 0.9W/sq.ft., says Pistochini, development engineer for CLTC. “Giving individuals control of their lighting is important for achieving both user satisfaction and efficient use of energy.”
“The results showed that if we look beyond technology and include human factors and common sense, we can still find simple solutions that can be easily applied to save more than 50% lighting energy in existing commercial buildings,” says Pete Horton, VP market development for Watt Stopper/Legrand.
An advantage of bilevel switching is that users have a choice of light levels, enabling them to adjust light levels based on preference for different tasks or lighting conditions, such as the variable availability of daylight.
Pistochini says about half the study participants preferred the auto-ON to 50% scenario, while the other half preferred complete control and therefore preferred to the manual ON scenario. “The hypothesis with automatic-ON to 50% is that the occupant, when presented with manual-ON switches, will not give much thought to the amount of light needed and turn ON both of them. With the automatic-ON to 50%, the occupancy often enters the office, finds the light level acceptable, and continues working. Occasionally, they desire more light and turn ON the other switch.”
“This study indicates that there is still a lot of room for lighting energy savings in new and existing buildings,” says Horton. “If you are looking for energy savings and a good return on investment, combining bilevel switching and occupancy sensing appears to offer one of the highest values a building owner can achieve.”
He believes this research will be influential, pointing out that because 46-52% energy savings higher energy savings can be demonstrated with bilevel occupancy sensing compared to standard occupancy sensing, energy codes are likely to address this approach in the future.
By Lighting Controls Association, on April 13, 2008
The National Electrical Manufacturers Association (NEMA) has published LC 1-2007 Test Procedure for Compatibility of Hearing Aids and Ultrasonic Lighting Control Devices.
This standard provides a basis to evaluate the possible interactions between ultrasonic lighting control devices and hearing aids utilizing a set of test procedures. This evaluation can be used as the basis for specifying performance criteria for both hearing aids and occupancy sensors to eliminate interference.
According to Bob Erhardt, former chairman of NEMA Lighting Controls Section, LC 1-2007 addresses compatibility between hearing aids and ultrasonic lighting control devices (occupancy sensors). Some occupancy sensors may occasionally interfere with acoustic signal processing in some digital hearing instruments causing audible noise and distortion of the signal.
“This publication provides a basis to evaluate the possible interactions between ultrasonic lighting control devices and hearing aids by specifying a set of test procedures,” Erhardt said. “This evaluation can be used as the basis for determining performance criteria for both hearing aids and occupancy sensors to eliminate objectionable acoustic interference.”
LC 1-2007 establishes test procedures for use with a small acoustic chamber to evaluate potential interactions between hearing aids and occupancy sensors. The test procedures are designed to simulate and test occupancy sensors at three typical, specific frequencies (25 kHz, 32.7 kHz, and 40 kHz) and one type of hearing aid.
“If there are multiple hearing aids,” Erhardt said, ”the test procedures are repeated as many times as necessary.”
The contents and scope of NEMA LC 1-2007 may be viewed, and a hard copy or electronic copy purchased for $38, by visiting NEMA’s Web site at http://www.nema.org/stds/LC1.cfm, or by contacting IHS at 800-854-7179 (within the U.S.), 303-397-7956 (international), 303-397-2740 (fax), or on the Web at global.ihs.com.
By Craig DiLouie, on April 12, 2008
Education has become a major construction market in recent years. In 2005, about $80 billion in spending made the K-12 and higher education markets the largest nonresidential segment, which held in 2006 ($85 billion) and 2007 ($100 billion) and will likely hold in 2008-09.
And it’s a good thing, too. Each year, more and more students are using facilities that are getting older and older, and using them differently than previous generations.
 Figure 1. Lighting typically represents 30-40% of school utility costs. Consider that in the fall of 2006, nearly 50 million students began using more than 385,000 school buildings; the number attending public elementary and secondary schools had risen 24 percent since 1985. According to the U.S. Department of Energy, just a few years before—in 2003—more than 60% of all school floorspace had been built before 1980, and 40% of that space had never been renovated. And students are increasingly using whiteboards, computers, Internet and multimedia, making classroom design as sophisticated as hi-tech corporate board rooms and conference spaces. To top it off, energy codes are becoming more and more restrictive on schools: A maximum power density of 1.6W/sq.ft. for classroom is prescribed by ASHRAE Standard 90.1-1999/2001, 1.4W/sq.ft. by ASHRAE 90.1-2004/2007, and 1.2W/sq.ft. by California’s Title 24-2005.
So the public and private sectors are spending record funds on school construction, renovation and modernization. Demand for lighting quality and flexibility is increasing to keep up with new visual needs, and the amount of power available for lighting is decreasing. This implies that tough design choices must be made; as the average school building built today will last the next 40-50 years, these choices are critical.
The high-performance schools movement, promoted by organizations such as the Collaborative for High Performance Schools, provides guidance on how to achieve schools that have good lighting, indoor air quality, temperature and humidity and acoustics, and minimized energy consumption, resource allocation and costs. Reducing energy costs is welcome to most schools; lighting alone typically devours 30-40% of school utility expenditures. But is lighting up to the task? Can today’s lighting technology provide a quality visual environment with the kind of flexibility required in high-end conference rooms, while minimizing energy costs and meeting tough energy codes?
The New York State Energy Research and Development Authority (NYSERDA) took this one step further by basically asking what’s the best value in school lighting, with value being defined as the most appropriate lighting for the lowest energy cost?
NYSERDA sponsored a demonstration project featuring a new Integrated Classroom Lighting System (ICLS) created by Finelite, Inc., a fixture manufacturer, installed as a retrofit into 28 existing classrooms at seven schools and universities. The Lighting Research Center (LRC) assessed teacher and student satisfaction.
The result is a design template demonstrated to satisfy audio-visual needs and improve teacher and student satisfaction while reducing lighting power density to an average 0.73W/sq.ft., nearly 50% less than ASHRAE 90.1-2004/2007. Although Finelite optimized the design into an engineered system integrating the company’s light fixtures with state-of-the-art lighting control strategies, the template, if properly designed, can be treated as open source with suitable products from a wide range of manufacturers.
The design typically is composed of two rows of direct/indirect pendants with a wallwasher whiteboard fixture mounted on the main teacher board. The fixtures are placed parallel to the window, with the rows spaced 14-15 ft. apart.
 Figure 2. The ICLS template. Legend:
1) Two rows of two-scene indirect/direct luminaires mounted perpendicular to the main teaching wall (parallel to window wall) and spaced 14-15’ apart.
2) A dedicated luminaire is used to illuminate the whiteboard on the main teaching wall.
3) Teacher control is placed at the front of the classroom. For easy teacher access place controls within 6 inches of the whiteboard.
4) Sensors are placed in the center of the classroom. Sensors always include occupancy and daylight harvesting is added where appropriate.
5) A master ON/OFF switch is by every door to the classroom.
Each fixture uses three high-performance (3100-lumen) T8 lamps—with one inboard lamp providing the downlight component and two outboard lamps providing both uplight and downlight. The inboard lamp and outboard lamps are electrically separate so that they can be separately controlled.
The fixtures are integrated into a lighting and control system featuring a ceiling-mounted dual-technology occupancy sensor placed between the rows of pendants, a master switch at the door and a “teacher control center” located near the main teaching board, which features:
- A “Whiteboard” switch that turns the wallwashing fixture mounted on the main teaching board ON and OFF;
- A “General/AV Mode” enabling the teacher to switch between General mode (downlight OFF, uplight/downlight ON) and A/V (and reading) Mode (downlight ON, uplight/downlight OFF; and
- A “Quiet Time” switch that overrides the occupancy sensor for one hour, keeping the light on during long periods of occupied non-movement such as standardized testing.
 Figure 3. The “Teacher Control Center,” which was mounted 6 inches from the main teaching board. Teachers were also able to access another option, A/V Dimming Mode, which allowed them to turn on and then dim the inboard lamp providing the downlight component. This required a dimmable ballast. All controls were connected via a CAT-5 plenum-rated low-voltage line with plug-and-play connections.
Optionally, a photosensor can be added, adjusting light output based on daylight availability.
 Figure 4. Hunter High classroom with the lights on General Mode.  Figure 5. Hunter High classroom with the lights on A/V Mode. Watt Stopper/Legrand provided off-the-shelf power and auxiliary relay packs to accomplish the fixture switching, the occupancy sensors with the customized Quiet Time feature, and switches for the teacher control station (through its sister company Pass & Seymour Legrand). Click here to see an interview with Jon Null, Director of Marketing for Watt Stopper/Legrand, about this project, or scroll down.
Results:
- Because all three lamps cannot be ON at the same time, the maximum lighting power density is capped at about 0.8W/sq.ft.
- The switching controls reduced average lighting power density to 0.73W/sq.ft., about half of ASHRAE 2004/2007 and about 40% less than Title 24.
- The LRC found that teachers generally preferred ICLS to the previous lighting system and that students also rated it favorably.
- The system was installed for $1.83-$2.29/sq.ft.; options such as daylight switching and a third fixture row to increase uniformity, add to the cost).
- The LRC found that installers generally characterized the system as “easy to install.”
- The design is suitable for both new construction and retrofit.
 Figure 6. The combination of energy-efficient lighting and integrated controls reduce average lighting power density to an average 0.73W/sq.ft. Click on the image to see it enlargened in a new window. Direct/indirect lighting and separately controlled fixtures for general and main teaching board lighting are considered best practices by the Collaborative for High Performance Schools. Optimizing this approach as a system with integrated controls maximizes its utility for A/V functions while minimizing energy consumption. Many of the research findings of this study are being incorporated into best practice developed by the Collaborative as well as the U.S. Green Building Council’s LEED for Schools green building rating system, according to LRC.
For more information about ICLS, including the complete reports on the California Energy Commission and NYSERDA demonstration projects, click here.
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