Last month, I disparaged LED "light bulbs" as nostalgia - a public reluctance to give up medium screw sockets and the familiar form of Mr. Edison's incandescent lamp. However, they actually serve as a gateway lamp, introducing this technology and opening up general acceptance for an entirely new way to deliver light. The color rendering quality and the lumen per watt efficacy of white LED sources can now surpass that of premium fluorescent lamps. Available in a range of warm and cool color temperatures, just like fluorescents, LED sources can provide excellent quality illumination.
Similar to all solid state devices, LED lighting started as a high-cost, low-efficiency, but exciting technology. With its flashy color-changing capability, it was quickly adopted for special effect and display lighting. Since the mid-90s lighting designers like me have been saying year after year, "LEDs will be ready as an architectural lighting technology in another 5 years."
So, is it really the right light, right now? My answer is yes, for the right application. The cost of LED lighting is dropping while the reliability and performance is improving. In terms of quality lumens per watt, LEDs are excellent for task lighting, accent lighting, and other situations where a small, low energy, low heat, long life source makes sense, even if it is more expensive than a clunkier fluorescent system or an energy-hogging halogen system. From a dMass perspective, a tinier task light or cove light is obviously preferable.
An example from our project portfolio is Yale's Harvey Cushing Medical Library, recently featured in Architectural Lighting. Housed in a new subterranean space beneath the Yale School of Medicine library, the Cushing Center displays the extensive collection of brain specimens, artifacts, and archival materials amassed by prominent neurosurgeon Dr. Harvey Cushing during the early part of the 20th century. Designed as an exhibit, research, and meeting space, the Center features custom millwork with carefully integrated LED lighting to illuminate this unique collection and provide a singular visitor experience. This system delivers the desired visual quality and meets curatorial requirements for low-heat, low-UV lighting that turns itself off when the space is empty. We decided to use tiny warm-white LED strips by KKDC in a channel located at the bottom front of each cabinet to uplight the jars. This provided the desired glow for the brains and the handwritten labels without overheating or overlighting the enclosures. Horizontal displays of Cushing's manuscripts and print material, built into the cabinetry, are illuminated with concealed linear LEDs. Vertical display units have adjustable point-source LED accent luminaires.
I am still reluctant to use LEDs for general ambient lighting. Linear fluorescent lighting provides comparable lighting or quality lumens per watt, but at a much lower cost per lumen. New fluorescent lamp and ballast combinations are extending lamp life to more than 35,000 hours, rivaling the sometimes questionable claims of 50,000 hours for LED sources. So far there aren't any LED ambient luminaires that are less massive than fluorescents, so I can't use that angle yet. But I expect to see that change in the next few years as flat organic LED panels improve in performance, reliability, and cost. Fluorescent is now a stranded technology that will be extinct in another 10-20 years. Nostalgia works for incandescent light bulbs, but no one (except lamp manufacturers) will mourn the demise of fluorescent lighting. Stay tuned.
Lighting and environmental designer Mark Loeffler is a Director at Atelier Ten and a regular contributor to dMASS.net.