When SSL is properly operated within its temperature and operating current ranges, it has a relatively long life, which reduces maintenance and improves reliability. Because SSL may not burn out but only decrease in light output, there is a potential liability issue if light output drops below design levels. Proactive maintenance strategies can be developed to alert users through intelligent controls when SSL drops below 70 percent of initial light output. SSL drivers can be made to adjust operating current so that when lamps are new, the operating current is lower. As lamps age, the operating current increases to maintain consistent light output. Near the end of usable life, indicators may be used to signal low light output.
Luminaires of entirely new form factors may be developed to take advantage of the unique attributes of LEDs and OLEDs. For instance, neither replacement lamps nor retrofit luminaires capitalize on the very small size of individual LEDs. This characteristic alone, if fully exploited, has the potential to completely change where and how electric lighting is used. The controllability of LEDs is also only beginning to be explored. Common lighting controls now are limited to dimming, occupancy/motion sensing, and daylight sensing. The next generation of SSL luminaires will be able to do those things and perhaps much more: change color, change color rendering properties, and so forth. Because the ability to control different light properties is determined by the components in the product, controls will most likely be considered integral parts of the luminaires. OLED’s unique properties naturally lend themselves to out-of-the-box thinking, and truly novel luminaire designs may emerge with new OLED products. Other applications may include lighted surfaces such as walls, ceilings, and furniture systems.
Adoption of these new and novel types of luminaires would require the most risk and investment by consumers. If a consumer were to become dissatisfied with a very innovative SSL luminaire, reverting to other lighting technologies would be difficult and expensive. Installation of highly innovative luminaires in existing buildings may necessitate major retrofit work. Thus it is likely that early adoption of such luminaires will be in new construction projects that pay attention to lighting design from the early stages of architectural planning.
A small sampling of these types of forward-looking luminaires has been developed. One interesting example is a closet rod embedded with LEDs, which becomes luminous when the closet door is opened (Reo, 2011). This custom-made product illustrates a clever use of controls and great attention to putting light where it is actually needed in a closet. Future lighting may emphasize flexibility and multi-function, as illustrated by a multi-functional OLED luminaire, which consists of multiple, movable OLED panels (Figure 5.2). It is possible that future lighting will make luminaires invisible, as is done by some LED products that are small and thin and intended to be installed in small crevices and recesses in the built environment.4 At this stage, it is impossible to predict all of the forms that future SSL luminaires will assume.
FIGURE 5.2 Example of multi-panel OLED (Canvis® Twist by Acuity Brands). SOURCE: See http://www.acuitybrandsoled.com/creations/canvis-twist/.
FINDING: Were OLEDs to become commercially viable, they would provide an opportunity to change the form factors of how luminaires are designed with smaller sizes, less material, and fewer physical constraints and offer an ability to change from traditional-looking luminaires to internally lighting surfaces and materials.
As with any new technology, the early adopters have highlighted areas in which further improvements are needed to make SSLs fully equivalent across the whole spectrum of lighting applications. Whenever a new technology is introduced, dissimilarities are noticed. For example, when the CFL was introduced to replace the incandescent lamp, users were unhappy with the flickering, slow start-up, color, light intensity, noise, radio static, and lack of dimming. It will be important not to make the same mistakes with SSL introduction (see the Chapter 2 section, “Compact Fluorescent Lamp Case Study”).
At this point, the major challenges to full acceptance of SSL are cost, system and control compatibility, and heat management. These issues are not well understood by most end users, so it falls to the lighting industry to improve