Back to the future: an innovation from the 1990s helped Fagerhult solve the LED equation

All the efficiency and all the visual comfort. How do you solve the light industries trickiest equation? The clues were in the past and the classic r5 louvre, the answer? Fagerhult’s Beta Opti, a double parabolic louvre developed exclusively for this light source.

“It’s all go now. After years of discussions, preparations and product development, LED technology is commercially ready. Customers are more informed and discerning with both the efficiency and, increasingly, the light quality they expect from their LED investment,” says Leif Norrby, Product Development Director at Fagerhult.

During the 00s, the lighting industry switched arena from being a standard manufacturing focusing on conventional light sources to part of the electronics industry. Years of standard practice was rapidly transformed, Fagerhult for instance, started producing luminaires for fluorescent tubes in the 1950’s, as the migration from T5 to LED took place in little over a decade.

“We were offered a unique opportunity to use the new, more efficient T5 fluorescent tube which was also smaller. With our innovation-driven corporate culture – Fagerhult has always been open to new technology and materials – it was a challenge not to be missed,” Leif Norrby remembers. 

The transition to T5 involved a number of technical lighting considerations.

“The louvre was the main focus. The existing reflector technology, based on double-parabolic louvres made of anodised aluminium, couldn’t benefit from the increased efficiency of T5. That’s why we chose to develop a completely new louvre based on the new light source.”

 Fagerhult Beta LED lamellasThe innovative r5 louvre built on a new combination of a side and top reflector in addition to a cross reflector, the latter was the fulcrum for increased control of the light distribution. Using new manufacturing technology and a new metallised aluminium material called Miro, we succeeded in creating an efficient louvre that reinforced the all the benefits of the T5 light source. By using Miro, the reflection factor increased from 86% to 95%.

“Another crucial point was the temperature inside the luminaire. T5 performed best at 35°C, compared to T8 which performed best at 25°C. By building louvres and luminaires with inside temperatures adapted for T5, we increased the efficiency even further.”

r5 was also developed to satisfy the more stringent cut-off requirements.

“We realised that a smaller, more intensive light source also involves a greater risk of glare. Visual comfort had long been part of Fagerhult’s signature and was not something on which we were willing to compromise.”

 r5 was launched in 1998. The combination of T5 and electronic ballasts became a new standard in the market, but as early as in 2010 it was time for a new generation. When LED was first introduced as a light source it was primarily used in downlights. Fagerhult launched its first luminaires for general and work lighting in 2013.

“The r5 project taught us a lot. Just like T5 in its time, LED posed a real challenge. Both cases involved new, relatively unexplored light sources that were very light-intensive compared with the incumbent variety. We knew how difficult it was to take a new light source and dress it in an old suit. If existing louvres and reflectors do not have the capacity to control and manage the power of the light sources – which they didn't in either of these cases – you risk both the efficiency and, above all, the lighting comfort. The high intensity of LED brought matters to a head. This small, intensive light point risked dazzling people  in a completely different way to the long, narrow fluorescent tube.”

There were a number of reasons to be wary. The early LED modules varied a lot in quality – from service life and deterioration to colour reproduction and colour temperature. The LED modules requirement for an efficient cooling mechanism also necessitated luminaires designed solely for use with LEDs. Otherwise you risk letting the fire go up the chimney with LED modules that will break in the future.

When Fagerhult rolled out the first big LED series, the focus was on luminaires developed from scratch. Just like other manufacturers, Fagerhult chose to work with microprismatic louvres to satisfy the requirements for energy efficiency and lighting comfort.

“Our aim has always been to create a double-parabolic louvre that can also improve performance and user experience. This is why we developed a new r5 generation customised for LED. Beta Opti makes use of the benefits of Medium Power LED and gives us completely new options for efficient and ergonomic control of general and work lighting.”

Beta LEDBeta Opti is based on a modified r5 cross-blade that, in combination with side reflectors and a diffusing film, provides complete control of the luminous flux. The efficiency has gone from 70 lm/W (T5) to approx. 120 lm/W and the aim is to achieve an even better value. The louvre has two different modules: one with direct light and one with an advanced combination of direct and wide-beam indirect light.

“The traditional long, narrow luminaire shape is based on fluorescent tubes. With LED the prerequisites were different and that’s why we’ve tried to create a uniform light for long surfaces as well. The luminaires with Beta Opti satisfy the cut-off requirements in EN 12464-2 and I would claim the lighting comfort is better than when using conventional light sources. Aesthetically speaking, a double-parabolic louvre is also a welcome alternative to the microprismatic and opal louvres.”

The launch of the Beta Opti reflector is Fagerhult’s signal that LED technology is ripe for full-scale implementation. However, Leif Norrby expects the development to continue at the same intensive pace, but with increased focus on quality.

“On average, a new more energy and cost-efficient LED version is launched every eight months. This is a development with which we have to keep up. Lighting will also be an important part of the new digital infrastructure where connectivity and Internet of Things are key concepts. It is a complex process that we follow with great interest. In the future I think lighting manufacturers should expect our assignments to be further displaced – we will become more valued as sub-consultants.”

“But our most important assignment in the future is to maintain visual comfort. It’s so easy to get carried away and allow yourself to be swept up by the quick development of efficiency and performance. LED is an unbelievably intensive light source and we must remember that in everything we do. We cannot let a hundred years of experience go down the drain. Technology exists to serve man.”