@misc{discovery10159119,
       booktitle = {Behave Energy Conference 2014: Paradigm Shift: From Energy Efficiency to Energy Reduction through Social Change},
           month = {September},
            year = {2014},
           title = {Saving energy through changing light: The impact of illumination on thermal comfort},
        keywords = {thermal comfort, light, colour temperature},
             url = {https://www.eceee.org/events/calendar/event/behave-energy-conference-2014/},
        abstract = {The 'Hue-Heat Hypothesis' states that light with wavelengths predominantly at the red end of the spectrum (or of a low colour temperature) are felt as warmer, whilst light with wavelengths mainly in the blue end (or of a high colour temperature) are felt as cooler. If confirmed, the Hue-Heat-Hypothesis could be a powerful tool for energy savings:  Temperatures could be lowered under a reddish light in the heating season. Conversely, less air-conditioning might be needed during the cooling season if higher temperatures were accepted under a bluish light. Even a transitory effect would be beneficial in managing power demand by allowing building temperatures to drift over a wider range of temperatures before heating or cooling was required. 
We used an experimental design to study the Hue-Heat-Hypothesis. Testing took place in a climate chamber, in which ambient temperature, relative humidity, and air speed can be controlled.  We installed a LED-lighting system in the chamber covering the range of correlated colour temperatures from 2700K, a warm, reddish light, to 6500K which appears bluish-cold. Participants (age range 18 to 35 years) were exposed to combinations of colour temperature and ambient temperature and completed standard thermal comfort surveys at specific time-points. Prior to testing, participants filled in a survey that asked about other factors potentially impacting on thermal comfort. 
In Study 1, temperature in the climate chamber was cooled continuously from 24oC to 20oC over a 60-minute period. Comfort ratings were obtained every 10 minutes. Participants (N = 32) were either exposed to a colour temperature of 2700K or 6500K (between-subjects design). Thermal comfort was higher under the warm colour temperature (2700K) than under the cold one (6500K). This difference was particularly pronounced for temperatures around 21 and 22oC. For the same subjective thermal comfort rating, ambient temperatures differed by around half a degree under the different lighting conditions. The magnitude of the effect varied with temperature (greatest effects observed around 22-23?C) and by comfort question asked. 
In Study 2, a within-subject design was used. Subjects were exposed to three different lights (2700K, 4440K,6500 K) with temperature decreasing from 23oC to 19oC. Preliminary results were similar to those of Study 1 with higher comfort under the warm-appearing light. Comfort ratings under the medium colour temperature of 4400K were positioned between the higher ratings obtained for 2700K and lower ratings for 6500K, again, only in a limited corridor of ambient temperature.
In Study 3, light was changed gradually from a cold to a warm colour temperature whilst ambient temperature decreased from 23oC to 19oC. Testing is on-going, but initial results indicate that the changes in self-reported comfort under decreasing temperatures are slower in the condition of changing light dynamically than under a stable 
Our studies support the Hue-Heat-Hypothesis. Varying the ambient light has an effect on thermal comfort and hence may be a suitable tool for energy savings and reducing of peak power demand.},
          author = {Huebner, Gesche M and Shipworth, David and Gauthier, Stephanie and Chan, Wing-San and Witzel, Christoph}
}