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Seeing red: the impact of light colour on thermal comfort and energy demand in cities


  • Dr David Shipworth (UCL Energy Institute)

Main collaborator:

  • Dr Stephen Hailes (Computer Science)

Additional Collaborators

  • Gesche Huebner (UCL Energy Institute)
  • Stephanie Gauthier (UCL Energy Institute)

The ‘Hue-Heat Hypothesis’ states that light waves with wavelengths predominantly of the red end of the wavelength spectrum are felt as warm and those toward the blue end as cool(er). Manipulation of the light colour could hence be a powerful tool for energy-saving in buildings if temperatures could be lowered under a reddish illumination in the heating season, or, conversely, be kept higher under bluish illumination in air-conditioned buildings.

The potential of energy savings through changes in illumination are large: We spend about 20 hours per day indoors, often under artificial illumination, and most carbon emissions are created through space heating.