By July 15, 2004, the U.S. Department of Energy will require all states to incorporate stringent lighting standards into building codes or to justify why they can't meet the standards. The new building codes require reductions in energy consumption from lighting by as much as 37.5 percent compared with existing code requirements.
Today, only 18 states meet these tougher standards. Many states are scrambling to update their codes, and many facilities managers are left in the dark about their responsibilities under the new codes.
Although the codes apply to new construction and renovations, active lighting control makes sense for existing school buildings as well. Savings are likely to be greater for older buildings — those built before the mid-1980s — as these buildings' lighting systems consume more energy. The New Buildings Institute estimates that lighting controls can reduce energy consumption in existing buildings by up to 50 percent. That works out to an overall reduction of up to 20 percent in the building's energy costs.
Many schools already have replaced old, energy-hungry HVAC equipment with improved models, upgraded insulation, and installed energy-saving fixtures and ballasts. Controlling when and where light is used is another prime opportunity for energy-related cost savings.
But financial considerations aren't the only reason schools should adopt this technology. Administrators recognize that it's the right thing to do from an environmental standpoint, and energy conservation is a responsibility they take seriously.
The diversity on a typical school campus offers many savings opportunities, but it also makes the job more complex. Lighting-control strategies should be invisible to users where possible, and intuitive everywhere else. Equipment must be reliable and robust. The latest generation of devices and systems are highly reliable, incorporate “learning” monitor usage patterns and adjust their sensitivities accordingly.
Active lighting control uses a combination of devices, ranging from simple standalone devices, such as dimmers and occupancy sensors, to sophisticated computer-controlled systems. Even the most advanced systems rely on well-established elements:
Dimming power packs are the basic building block for active lighting control. They act as the interface between the various control devices and the lighting fixtures.
Timers turn lights on or off at prescribed times. Timers can reduce lighting during off hours. They also can be operated manually.
Occupancy sensors turn lights on when they sense human activity and turn them off when nobody is around. They save energy and enhance safety and convenience. No one has to enter a darkened classroom to hunt for the light switch, stumble down a dark hallway in the middle of the night, or cross an abandoned plaza in the dark. And nobody has to remember to turn off the lights when leaving a room.
Photocells measure light levels, allowing artificial lighting to supplement natural daylight.
Control systems integrate all of these elements into a centralized programmable system that can be linked to other building systems.
The simplest control strategies use timers and occupancy sensors to reduce the biggest source of wasted lighting energy: lights in empty rooms. When usage is predictable, such as in office areas, timers can be set on 24-hour cycles to reduce lighting during off hours. In addition, timers can be set on shorter intervals and accessed by a keypad. In this way, for example, lights can be turned on in a classroom and will shut off automatically after a set period of time.
Occupancy sensors provide more flexibility: by actively sensing when an area is in use, they can help ensure that lights are used only when they're really needed. These devices don't require network control. They simply can be hard-wired to the fixtures they control. They're highly reliable and require little attention from users or facility managers.
Networked lighting-control systems allow greater control over an entire facility. In addition, they permit facilities to employ more advanced strategies such as daylight harvesting and user-controlled lighting.
Daylight harvesting takes full advantage of natural daylight, adjusting the level of artificial lighting as daylight levels rise and fall. Photocells monitor light levels throughout the day. As daylight increases, these sensors adjust the lights, adding only as much artificial light as needed to maintain a steady level of illumination. The fixtures are controlled by multiple photocells, so light levels are balanced automatically throughout a space. The result is a seamless blending of light sources. Schools can reduce energy consumption in those areas as much as 60 percent.
Supplanting artificial light with daylight offers aesthetic and performance benefits as well. Studies have demonstrated increased productivity among office workers and improved test scores among students when diffused natural daylight is the primary source of illumination.
User-controlled lighting employs desktop controls that allow individual users to adjust lighting in their own work areas. This technology is especially suitable for administrative and office areas, where it saves energy and can improve productivity and worker satisfaction.
Individual lighting needs can differ greatly. One factor is aging; the older we are, the more light we need. The eyes of a 60-year-old, for example, receive only about 40 percent as much light as those of someone in his or her 20s.
Active lighting-control projects can range from a single building or office area to an entire campus. A limited program can provide a learning opportunity, a chance to measure savings and verify return on investment — and can be funded more easily. A comprehensive program, on the other hand, generates bigger returns and achieves economies of scale.
One strategy is to upgrade first in the highest-payoff areas — older buildings with less-efficient lighting. Another strategy is to integrate lighting upgrades into an ongoing maintenance program to minimize disruption and allow gradual conversion.
Administrators need to define the project scope and estimate potential return on investment. Lighting consultants and equipment manufacturers can help provide estimates of potential savings.
Using these calculations, the facilities engineer and lighting consultant can create a detailed plan that provides the best return on investment without creating negative effects on students, faculty and staff.
Keep in mind not only direct energy savings, but also “softer” factors. Using motion detectors in outside areas, for example, contributes to security and a sense of safety among staff and students. Occupancy sensors in hallways can help prevent slips and falls. Installing timers in offices that face busy streets or neighborhoods can enhance community relations.
As the lighting is being upgraded, it's important to communicate to faculty, staff and students about the new technology and how it works. It's also important for users to give the controls time to adapt. State-of-the-art occupancy sensors, for example, have a brief learning period during which they learn users' habits and factor in usage patterns. The sensors learn to sort out signals that would otherwise falsely activate the lighting controls.
Finally, it's useful to solicit feedback to identify and correct any problem areas, such as “blind spots” that occupancy sensors are overlooking. Usually the solutions are simple, involving fine-tuning of equipment or additional sensors.
Leonard is marketing director for the lighting control division of Leviton Manufacturing Company, Little Neck, N.Y. He has been involved with facilities and design in the technical application of lighting controls and related products for 15 years.
Compared with existing code requirements, percentage that new buildings will be required to reduce their energy consumption from lighting after July's U.S. Department of Energy new stringent lighting standards.
Number of states that already meet new U.S. Department of Energy stringent standards, which will become required for all states after July 15, 2004.
Percentage of energy consumption that can be reduced by lighting controls, according the The New Buildings Institute.
Percentage of a building's total energy costs that can be reduced when using lighting controls, according to The New Buildings Institute.
New energy code looks at lighting
The U.S. Department of Energy will require all states to include active lighting controls in building codes by July 15, 2004, unless a state can demonstrate why it can't meet these new standards. Most states are expected to comply.
The code requirements are based on the ASHRAE 90.1-1999 Energy Standard, and will affect all new construction of more than 5,000 square feet, except for low-rise residential structures.
Standard 90.1-1999 sets lighting power allowances for interior and exterior applications. Power allowances for interior applications can be calculated using one of two methods: the “whole-building” or “space-by-space” methods:
- The whole-building method
This method measures watts per square foot for the entire building, with different levels for different types of buildings:
Office buildings: watts per square foot are reduced from 2.1-3.3 under the old standard to 1.3.
Retail buildings: watts per square foot are reduced from 2.1-3.3 to 1.9.
School buildings: watts per square foot are reduced from 1.5-2.4 to 1.5.
- The space-by-space method
Alternatively, lighting power allowances can be calculated for individual spaces:
Space Old Standard New Standard Office (enclosed) 1.8 1.5 Office (open) 1.9 1.3 Conference 1.8 1.5 Training 2.0 1.6 Lobby 1.9 1.8 Lounge/dining 2.5 1.4 Food prep 1.4 2.2 Corridor 0.8 0.7 Restroom 0.8 1.0 Active storage 1.0 1.1
Standard 90.1-1999 mandates that either timed scheduling or occupancy sensors be used for buildings larger than 5,000 square feet, except for lighting operated 24 hours a day. Control devices may include:
Programmable time-scheduling systems that turn lights off during times of day when spaces are unoccupied.
An independent program schedule for areas less than or equal to 25,000 square feet, but not more than one program per floor of the building.
An occupancy sensor that turns lights off within 30 minutes after the space is vacated.
An unoccupied/shut-off control signal from another control or alarm system.
Rend Lake College keeps energy consumption flat despite growth
The lights were on, but nobody was home.
That was the situation facing Rend Lake College, Ina, Ill. The community college serves 11,000 students annually, and was looking for ways to reduce its energy consumption. Dozens of classrooms and offices remained brightly lighted even when nobody was using them.
“We'd see classrooms that sat empty for hours every day with the lights turned on,” says Randal Shively, physical plant director. “In office areas, the lights stayed on from the time people went home until maintenance crews showed up hours later. And if the maintenance staff didn't turn the lights off, they stayed on all night.”
As part of a comprehensive energy-management program, Rend Lake College installed occupancy sensors in 30 to 50 classrooms and approximately 125 offices on the campus, which serves commuter students in southern Illinois.
The college can't put a precise figure on how much energy has been saved from these measures, says Shively, because the campus has been growing at the same time, and the school has installed more sidewalk lighting as a safety and security measure. But he estimates that the impact has been substantial. Despite the expansion and improvements, energy consumption campuswide has increased only 0.25 percent over last year, in month-to-month comparisons.