illumination Physics

Double Tree

by Hilton


llumination Physics were in the process of completing the façade lighting for a project in Croatia when asked by the client if we could look at another of his projects currently under construction.

For the most part, the building is conventional. Site progress photos informed us that the concrete pours were almost complete, meaning the façade panel installations were imminent. There was no time to make any changes to the curtain wall.


For illumination Physics, familiar golden rules surfaced:

  • The lighting must not cause any nuisance for the hotel guests.
  • The lighting must not require any electronics or transformers within the guest room areas.
  • The design of the lighting maintenance system should not affect the guests in any way.
  • It must appear as if the lighting of this building was pre-determined.
The polished and metal glass façade is of a conventional unitised curtain wall genre, rendering the use of indirect lighting impossible. Decorative fins are commonly used to add character and break up the slab-sided nature of a unitised façade. illumination Physics ensured this approach was followed at the Double Tree Hilton, with the exception of one remarkable difference – the decorative fins were to be made of wood! Decades-long experience of integrated façade lighting helped map the course of our solution. The architect had already decided to make the unique laminated wooded fins the eye-catching feature of the façade. Following his lead, the key to the new façade lighting would be to celebrate these unusual fins.

Lighting them indirectly was not practical and the chances of consistent grazing slim. Indirect light would also break golden rule number one – we would risk annoying the guests. 


The solution was a compact direct view LED luminaire integrated into the fin, an illumination Physics custom creation perfectly matched to the 32mm width of the wooden fin. To draw attention, it needed to be capable of dynamic change and be fully programmable. An unusual rectangular prism light fixture rapidly evolved from 3D drawings into a CNC machined prototype. A solid PMMA lens mimicked the dimensions of the wood that had been cut from the base of the fin, looking as if it had always been part of the physical design. What followed was the subtle use of cool white and warm white, used in slowly evolving lighting scenes befitting the up-market aspirations of the building’s image.

The new luminaire required high-powered LEDs given the lumen output, which raised some thermal issues that needed management. The solution lay in a simple modification to the wooden fins. A slot was opened at the base of the fin and the heatsink of the luminaire was designed as a slender cooling fin, itself possessing striations to increase its surface area for convective cooling. Air was drawn in at the base of the fin, passing over the heatsink of the luminaire and exhausted at the back of the fins via an invisible ventilation slot.

Accommodation of the new luminaire into the façade system required a specially made cable connector with a very narrow diameter. The electronic design of the luminaire system had to be so compact that the packaging of any electronics was very problematic. Whilst the operational temperature in the luminaire was manageable for the LEDs, this was not the case for the electronics, which have a heat tolerance less than half of the LEDs. From a life expectancy and maintainability perspective, on-board electronics made no sense. The most logical lighting system design was to use remote drivers located in the easily accessible building core. The luminaires were reduced to the ultimate durability born of simplicity, connected to those drivers by cables carrying no data, just low voltage.


As always, illumination Physics tailored a complete solution including the design and configuration of the control system. A complete package of control schematics and data distribution products was supplied with the drivers and luminaires. Our intimate understanding of the construction process for modern façades enabled us to deliver an integrated and innovative lighting system that could be installed without extending the overall construction phase.

Another example of illumination Physics’ in-built design.