4 FM quick reads on Lighting
1. Controls Offer Further Lighting Efficiency
Today's tip is to look at lighting controls for further energy savings after switching to more efficient light sources. Once efficient fixtures and lamps have been chosen, there are really only two ways to further reduce energy use: Reduce burn hours or reduce light output. To perform either of those functions, you need a lighting control.
Commercialization of several novel technologies has expanded ways to apply controls to both existing and new installations. Competition and standardization in wireless communications protocols, for example, now provide options that avoid the usually costly installation of separate control wiring, often a deal-killer when adding controls to existing lighting.
Wireless switching can use power generated by one's finger (when pushing the on-off button) to send a radio signal from the switch to a relay built into (or added to) fixtures in the same room.
Wireless stations, when directed by a control panel, send signals to receivers that control whole circuits of fixtures, or to groups of fixtures based on electronic addresses built into their ballasts.
Reliable power-line carrier control products, using panels and dimming ballasts (either step or continuous), have expanded and become cheaper, offering a third way to retrofit without requiring additional wiring.
These options are competing with the now-standard Digital Addressable Lighting Interface systems that use dedicated low-voltage wiring to control individual fixtures. DALI is often installed in new or heavily renovated facilities while ceilings are open and spaces are unoccupied. Wireless systems are often applied where spaces are already in use.
2. Photoluminescence can guide occupants out
Today's tip is to consider photoluminescent egress lighting to guide people out of your building in a fire or other emergency. The technique has been used for years on planes, trains and ships to assist evacuations, particularly when power is out. Today, photoluminescent egress lighting is being adopted by facilities to help guide occupants in emergencies when there is little or no light. The light typically glows in the dark to define a space or path so occupants can orient themselves and identify a safe route.
The components require no electricity, since they absorb energy from ambient light and re-emit it when the light is out. They are measured primarily by brightness and the amount of time they produce light. Performance depends on the pigment concentration, the intensity of light used to charge the pigment, how long the pigment is charged and the type of light used to charge the pigment. Fully charged, most pigments produce light at least eight hours, with the light level slowly decreasing.
Photoluminescent signs and markers require little maintenance and no electricity, other than to power the ambient light sources used to recharge them. They do not deteriorate from use and are nontoxic and non-radioactive.
New York City's Local Law 26, passed in 2004, law requires installation of photoluminescent emergency markings in any office building more than 75 feet tall, regardless of age. Part of Local Law 26 establishes the technical standard, RS 6-1, for installation of the signs and markings. The standard requires photoluminescent markings on:
- All exit doors
- All doors that lead to corridors that serve as exit passageways
- The entire horizontal leading edge or side markings of all steps
- The entire leading edge of all landings
- The entire length of all handrails (in new buildings)
- The entire length of all building egress paths
- Edge markings for any obstacle that projects more than four inches into an egress path
- Direction signs that point towards the means of egress.
In addition, "not an exit" signs must be posted over dead ends in a building.
Pathway marking systems for new and existing high rises are also required by the 2009 International Building Code and the 2009 International Fire Code.
3. Daylighting can reduce energy bills, improve satisfaction
Today's tip is to learn more about daylighting as a possible lighting strategy - but a well-thought-out daylighting plan requires more than just windows and skylights.
Along with minimizing artificial light and reducing electricity costs, daylighting can lower HVAC costs. Electric lights produce a lot of heat, but if properly controlled, natural lighting generates hardly any heat at all.
For most buildings, daylighting energy savings range from 15 to 40 percent. It can also improve the productivity and satisfaction of employees, students and even clients and retail customers, since people have a natural attraction and need for daylight. Even retail stores like Wal-Mart have seen the benefits of daylighting for both employees and consumers. In an experiment, stores that included skylights over certain departments found that overall sales per square foot were higher in the departments lit by natural light.
A high-performance daylighting system may initially require a significant investment. However, if the project team uses an integrated, strategic design approach, a company's overall long-term savings make up for it.
One important point is controlling glare. Direct sunlight penetration in classrooms and office spaces often produces an unpleasant glare on work surfaces, making it difficult to view a computer screen. Properly oriented windows and skylights can admit direct and diffused daylight, producing light while also reducing glare. The selection and placement of windows and skylights should be based upon climate and the design of the building.
Daylighting also must control the amount of heat that enters a building. Window treatments, window films and glazing can shade a window or diffuse direct sunlight. This can reduce overall cooling loads, eliminating the need for a larger cooling system, resulting in additional overall savings.
Some architectural features, such as a building's roof, atrium shapes or a building's angles, can prevent daylight from illuminating a space. To prevent daylight obstruction, wall openings should be strategically placed within the space. For example, if elements that can block daylight are located high up, they should be as far from wall openings as possible. In a plan that features both open and enclosed spaces, open space areas should be close to the wall openings. This maximizes the effect of daylight, reflecting light deeper into the space.
4. Consider exterior lighting upgrades as savings source
Today's tip is to look at your exterior lighting as a source of savings. Turning off exterior lighting loads for institutional and commercial facilities is the most effective way to save energy, but it might not address the lighting needs of the general population. People need some form of exterior illumination to feel safer and more secure. Beyond functional lighting, people also need lighting that enhances the nighttime atmosphere to encourage activity and make spaces feel inviting.
Every year, building codes and green building programs require that facilities further reduce energy consumption. Advances in technology have reduced loads for interior building lighting, but only recently have manufacturers considered extending these energy savings to outside.
Because organizations use exterior lighting to provide security and aesthetic appeal, it is no surprise that managers hesitate to turn off outside lights. But the lighting system for a parking lot designed in 1970 — or even 2000 — probably is outdated by today's standards.
Replacing the key components of a high-pressure-sodium fixture with LED lamps might reduce energy consumption and deliver a reasonable payback of two-four years — or, with rebates, instantaneous payback. Managers should be sure to specify LED sources from reputable, established manufacturers who have controlled binning standards, proven heat sinks and fixtures specifically tested and designed for their LEDs.
The most efficient LEDs are cooler white. In exterior applications, cool blue color temperatures also can result in reduced allowable lighting levels. But at least in the United States, cooler light — usually anything greater than 4,100 Kelvin (K) often is perceived as uncomfortable, sterile, and institutional. Building facades appear more inviting when illuminated with a warmer light — 3,000-3,500 K — that also has a high color rendering index (CRI). A CRI greater than 80 makes the finishes of materials and objects appear more true and rich.
Managers also should take care should to select a lamp that is compatible with the project's geographic location and the connected controls. Fluorescent lamps do not like low temperatures. Dimming ballasts also generally are not fond of temperatures below 50 degrees. Induction lamps are more compatible in cold environments, tend to produce less glare, and have one of the longest life spans. But they are not dimmable, and their distribution patterns can be difficult to control through fixture optics.
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