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Issue 74 Aug/Sep 2013

One of the stars of The ARC Show @ May Design Series, KKDC’s innovative products have been a hit with specifiers and consultants on major projects all over the world. David Morgan took a closer look at one of their new releases - the SIL window reveal light.

In the space of a decade, KKDC has emerged from relative obscurity to become a significant player in the global architectural lighting market. It originally developed its reputation by producing linear LED tape-based lighting systems that offered high colour consistency, high CRI and a wide range of colour temperatures earlier than its better-known rivals.

As it has grown, KKDC has created a strong brand identity and worked with high-profile architects on many projects, including the House of Stone in Milan with John Pawson and Salvatori. In 2011, KKDC managing director Tom Fairhall spoke of entering a ‘hyper growth’ period and, in the space of a few years, his organisation set up offices in the UK, Australia, New Zealand, France, China and Japan – not bad for a firm that began life as an OEM, producing products for Samsung.

KKDC’s SIL light is a recently-introduced luminaire, specifically designed to illuminate window reveals. This niche lighting application, so popular with lighting designers, has already been tackled in recent years by other companies including Sill and Meyer. However, the KKDC product is smaller – incorporating a single 3 watt LED – and neater than these earlier products and gives the impression of being targeted at residential rather than architectural projects given its quite low light output and low efficiency. In comparison, the Sill 190 luminaire incorporates 9 x 2 watt LEDs, while the more recently introduced Meyer Arclight has 2 x 3 watt LEDs.

In its general appearance, the KKDC SIL is attractive with well-finished surfaces and integrated branding details. The satin anodised end caps and matt black body give a good impression of well-considered luminaire design. The product design was by Tim Young, Design Manager, based in the KKDC UK office while production, mechanical design and the PCB/Electronics design was by Minkoo Park and Sanghun Jung respectively, both based in Korea.

The LED source is a single Cree XT-e run at 700 mA, fitted with what looks like a Ledil Flare series lens. This lens produces a 180-degree arc of light from a single LED source and is very well suited for this application. The light output is a very narrow blade of light with roughly 180-degree distribution. The effect, when used in a typical domestic window reveal, is attractive and the SIL illuminates the window reveal quite evenly without much spill light. There seems to be a bit of a glare issue when viewed from within the building. Although the lens collimates the light output effectively, it has a frosted central element that acts as a glare source and, under certain circumstances; this could be irritating when looking out of the building.  There is no mention of any add on anti-glare or anti-bird roosting accessories. At the moment only white light versions are available but possible fixed colour or colour changing versions may be introduced.

I was surprised to note the low efficiency of the luminaire with 3.79 watts input power producing only 72 lumens output, giving 18.9 lumens per watt. I assume that this is due to optical losses through the lens and cover moulding but perhaps thermal issues are also reducing performance.

The SIL incorporates a simple mechanical adjustment so that the light output can be adjusted to the desired angle. While the mechanism cannot be locked the hinge screws can be tightened after installation but this would be very fiddly in many situations.

Despite the small size of the SIL it incorporates a 4 watt mains voltage constant current driver to run the XT-E LED. This driver is from a little-known Chinese brand and is the smallest line voltage driver of this power I have seen so far.

The SIL has a single flying lead cable entry with a compression gland entry but no provision to terminate cables within the luminaire. The Meyer and Sill products both allow for looping wiring in and out with internal wiring connection which, although requiring much more space, is a useful feature for installers.

Although the luminaire is highly attractive and compact, the internal construction and LED thermal management in the sample I was given did cause me a few concerns but this was a pre-production sample produced rapidly for the ARC show so it would not be fair to comment about that in this review.  Hopefully these concerns will be addressed prior to full production. However I did wonder if the insulating moulded plastic body that encloses the primary heat sink would limit heat from radiating to the outer atmosphere as this is an integral part of the design. I understand that the KDDC technical team in Korea have fully tested the product and that the LED is running within limits.

I also wondered what provision had been made to prevent UV yellowing of the clear window in the plastic moulding given the potential high levels of direct exposure to sunlight. The area around the clear window has been painted satin black and this paint has a three year warranty. The Meyer and Sill products incorporate glass windows that do not yellow with sunlight exposure.

I am sure that the KDDC SIL will be a very useful and successful product in smaller scale projects where limited light levels are required. The lit effect is very pleasing and the detail appearance and size of the luminaire are well considered.

David Morgan runs David Morgan Associates, a London-based international design consultancy specialising in luminaire design and development.


The IP65 rated SIL LED Window reveal light features a total light output of 72 lumens with a luminaire efficacy of almost 19lm/W from a single 3 watt LED.

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