Solid-state lighting (SSL) has transformed the lighting industry and has had a great impact on the development of luminaires that use LEDs as their source. But while SSL technology has given the industry a starting point for new luminaire design, it has also presented a new set of issues that manufacturers and lighting designers have to contend with—issues such as appropriate metrics for LEDs, color rendering, and the replacement of individual elements within the overall LED luminaire package.

At the root of the matter is the very concept of the lighting system itself. Previously, one would select a luminaire and the coordinating lamp and ballast to go with it. And, for the most part, a designer could do that and use products from different manufacturers for the overall luminaire without too much complication. But with LEDs and their electronic complexity, the ability to use components from different manufacturers has been met with more difficulty. LED fixtures and their components, including the LED engine, heat sink, and driver, have thus far been designed as integral systems. This has made it impossible to use anything but one manufacturer's complete LED product line. Realizing the limitations that this puts on the continued evolution of LED luminaires, lighting manufacturers have been working to figure out a way to overcome this hurdle, and to share information without compromising proprietary research and technological developments that will distinguish them from their competitors.

An Industry Network One way the lighting industry is working to overcome these technology hurdles is with the formation of working groups, or consortia, where manufacturers with similar vested interests can work together and develop industry protocols. Zhaga is one of the first of these groups to have been established. Founded in February 2010, the group is an industry-wide consortium of global lighting companies.

Zhaga (the word means waterfall in Sichuan, but has no intended meaning otherwise for the group) was started with the aim of “creating specifications that will enable the interchangeability of LED light sources from different manufacturers.” Members include luminaire manufacturers, LED module makers, and material and lighting component suppliers. The nine founding consortium members are: Acuity Brands Lighting, Cooper Lighting, Osram, Panasonic, Philips Lighting, Schréder Lighting, Toshiba, Trilux, and Zumbotel. Since the launch, more than 200 companies from Asia, Europe, and North America have joined.

Establishing Protocols So how is Zhaga able to advocate for this desired interchangeability of LED light sources? It does this by defining interfaces for a variety of application-specific light engines. (An LED light engine is defined as the combination of an LED module and the associated control gear.) Zhaga specifications cover physical dimensions, photometric data, and the electrical and thermal behavior of the LED light engine. The interchangeability of the LED light engine is specified independently from the type of technology used inside the light engine. This way the interface stays the same, but the light engine can be replaced with a new one as evolutions in technology occur.

Industry Progress? So what kind of progress has Zhaga made in its first two years? Having so many of the leading lighting industry players involved is good, but it doesn't mean that reaching consensus on the specification formats has been easy. At present, Zhaga is working on the standardization of interfaces for downlights, general lighting, and spotlights. These are good starting points, as they already coincide with the areas in which LED luminaires have made strides product-wise. This will also allow Zhaga-based specifications to have a high market impact.

Zhaga members meet several times a year to discuss technology developments to further develop the standardization of these interfaces. Particular focus is given to the mechanical and thermal fit of the heat sink, the size and height of the light-emitting surface, and the photometric properties in regards to different application areas.

When asked about the current state of Zhaga and the challenges it faces going forward, Fred Bass, director of Neonlite, and a Zhaga member, notes, “Zhaga has achieved a great deal in two-and-a-half years, first by bringing together more than 250 industry players globally, [and] with more than 50 meeting regularly every couple of months.” But the key challenge is for Zhaga “to gain wider acceptance by both luminaire makers and specifiers,” he says. “It comes down to improving Zhaga's market communications to demonstrate the clear benefits of the sustainable approach Zhaga platforms offer.”

And while Zhaga's intent is good, one does wonder if it adds further confusion to this rapidly advancing area of lighting technology, at least until more people become familiar with the consortium and its activities. Nevertheless, as the consortium explains in its literature and on its website (, its purpose is to “benefit consumers and professional buyers of light engines and luminaires in the expectation that interchangeability will prevent market fragmentation into incompatible products.”

The consortium's hope is that the standardization and coordination of LED components that it is working toward will lead to an increase in a designer's confidence when it comes to specifying LED fixtures for a project. This should lead to further commercial availability, easy replacement, and continued performance upgrades, all of which should aid in speeding up innovation and improving competition in the application of LED lighting. The end goal for manufacturers is the delivery of stable design platforms.