Casting New Light on Comfort

The challenge

Using less energy in our buildings isn’t only good for the planet, it also saves tenants and building owners money. But who wants to wear their jacket indoors? How can we help people feel comfortable in our buildings without relying on the thermostat?

In this article

  • Integrating building systems using smart technologies.
  • Exploring how our perception of thermal comfort is related to lighting temperature.
  • Using multi-disciplinary problem solving to find less conventional solutions.

In an increasingly connected world, it’s odd that buildings, one of our most controlled environments, consist of multiple but separate systems. Although information from these individual systems are typically integrated and viewed simultaneously on a building wide building monitoring and control system (BMCS) they currently are not responsive to one another. For example, the light switch is entirely independent of the temperature dial. What if we were to link these functions within the digital system that controls a building so that when a high internal temperature is recorded, instead of increasing the cooling to that space, it reduces the colour temperature of the lighting as a first step to making a room feel cooler? And vice versa?

Lighting, along with heating, ventilation and air conditioning (HVAC), is one of the biggest usages of energy in commercial buildings. But as the watts per lumens have dramatically decreased in the last decade through LED technology and lighting control systems with daylight and occupancy sensors have improved, it’s hard to see where lighting technology can go next.

Whether we feel comfortable or not in an office depends on a number of environmental factors including but not limited to: air quality, humidity, acoustic ambience and visual ambience. Recent reports have shown a relationship between the perception of the thermal temperature of a room and the colour temperature of the light. Yes: it seems that our minds trick us into feeling cooler in a room with blue light, and warmer in a room with red light.

During a multidisciplinary workshop, Rebecca raised the idea of creating a feedback loop between systems in the building management system. Rebecca spoke to Dr Richard de Dear, Director of Building Science at The University of Sydney, and the research project was born.

Research has shown that our perception of thermal temperature in room is linked to the colour temperature of the light. Yes, we feel warmed in a room with red light and cooler in a room with blue.

“Perceived temperature is an important criterion in HVAC design. Therefore, we anticipated that changing the colour temperature of lighting in response to thermal set points could help us reduce HVAC energy consumption.” Rebecca explains.

In most commercial, office buildings the internal set point is controlled to 18-24ºC. If that band was widened by two degrees however, we think we could save about 15% in energy on HVAC systems across 30-60% of a building’s rentable area depending on usage profiles.

With the University of Sydney, we’ve installed tuneable white lighting in temperature controlled trial chambers, and programmed cues into the local control systems so that the lighting responds to the temperature of the room. For example, a thermal temperature of 23ºC will trigger the lighting temperature to climb from 4000k (base colour) to 5000k. And conversely, a thermal temperature of 18ºC will trigger the lighting temperature to change from 4000k to 3000k.

If we find that we can indeed trick ourselves into feeling more comfortable based on changes to lighting colour, then we will be able to apply this on projects to improve people’s comfort and wellbeing.

And on top of that, we may be able to reduce energy use in commercial buildings and incorporate this solution into Green Star and WELL Building Standards.

The team, from left to right: Samantha Goff, Dr Arianna Brambilla, Rebecca Cadorin, Wenye Hu


  • Taking a multi-disciplinary approach can push technologies further: integrating building systems like HVAC and lighting can improve efficiencies whilst maintaining peoples’ comfort and wellbeing
  • Our perceptive systems related to thermal and colour temperature may be used to impact positively on the environment, providing potential to shift thermal comfort bounds by two degrees Celsius.

This story was written by Eleanor Whitworth. The series is produced by the Arup Australasia Research team; Alex Sinickas, Bree Trevena and Jeff McAllister with contributions from Sheda and Noel Smyth.

Lead Arup Researcher

Rebecca Cadorin
Rebecca is a lighting designer in our Sydney Buildings team.

Ask Rebecca about:

  • The relationship between thermal and colour temperature and wellbeing.
  • Setting up lighting control systems to change colour based on thermal temperature.
  • Methods for reducing energy use in buildings.


Dr Arianna Brambilla
Arianna is a lecturer in architectural technology at the University of Sydney.

Research TEAM

Dr Richard
de Dear
Professor de Dear is from the Sydney School of Architecture and Planning.
Samantha is a mechanical engineer in our Sydney Buildings team.
Wenye is an Associate Lecturer at the University of Sydney

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