Arup office transformed in tuneable light study

LEADING ARCHITECTURAL and building services consultancy Arup has conducted a pilot study at its London office into the behavioural effects of dynamic spectrally-tunable lighting.

The office windows were blocked to avoid people being exposed to sunlight during work hours, and different light spectra, designed by a team of scientists, were used 

The nine-week trial experiment was designed to understand how ‘light sculpting’ could impact biological and psychological processes.

The experiment used technology from Spanish manufacturer Ledmotive, which consisted of an LED-based module made with seven different independent colours.

One of the colours was centred at the peak of the melanopsin curve, a measure of the production of the body’s natural sleep-wake hormone.

Dynamic custom-made light spectra sequences were applied throughout the day.

These were either spectra designed to mimic natural daylight changes or to achieve a certain level of non-visual stimulation.

The office windows were blocked to avoid people being exposed to sunlight during work hours, and different light spectra, designed by a team of scientists, were used.

One example is shown in graph 1, focusing on the dynamism of the melanopic response.

Subjective and objective tests were  then performed to assess the behavioural responses resulting from exposure to the special lighting, and to compare these with responses to a traditional lighting system.

From top: graphs 1 to 4  show the spectral output, colour temperature, and two spectral power distributions used in the experiment

The effectiveness of a given light spectrum in activating the so-called non-visual pathway – light receptors in the eye which aren’t connected to ‘seeing’ – was quantified by its melanopic lux in addition to visual factors such as photopic lux or correlated colour temperature (CCT).

In graph 2 is shown one of the specifications of an experiment.

While maintaining CCT and lux value, the spectral output was targeted to induce large variations in the melanopic lux.

The results will be presented at the LuxLive 2019 event in London in November to raise awareness of the importance of a circadian lighting design and the importance of having a full spectral control and not just tuneable white lighting.

It’s believed to be the first office installation in the world, where outdoor daylight streaming from a spectrometer readout was fed into an indoor area.

An IoT spectrometer, located at the rooftop of the building, was used to capture light outdoors and feed it into the Ledmotive lighting system via the cloud, effecting the lighting directly inside the office.

Subtle spectral changes outside were translated into subtle and smooth spectral changes inside the office.

The team behind the project include: Anya Hurlbert, Professor at Newcastle University, Newcastle; Florence Lam, Arup Fellow, Director Global Lighting Design at Arup, London; Rohit Manudhane, architect, daylighting and lighting designer at Arup, London; Castan Architectural Lighting; Ledmotive.


  • Learn more about the project at LuxLive 2019 exhibition, taking place on Wednesday 13 November and Thursday 14 November 2018 at ExCeL London. Entry is free if you pre-register HERE.