Introducing luminescent solar waveguides for sustainable buildings for enhanced circadian rhythm regulation

As the world strives towards a low-carbon future, nearly-zero energy buildings (NZEB) have been the goal to reduce carbon emissions. Artificial lighting is estimated to consume as high as 40% of the total energy consumption in a commercial building. By utilising daylighting, which is the practice of allowing natural light into a building, energy consumption by artificial lighting can be reduced. Luminescent solar concentrators (LSCs) can act as a collector and waveguide to transport outdoor light into the building through total internal reflection. Besides, LSCs absorb a part of the solar spectrum and shift them to different wavelengths through up-conversion or down-conversion. Thus, the output spectrum can be manipulated for the desired indoor applications. Circadian rhythm is the periodic variations in behaviour that follows a 24-hour cycle, which is mainly regulated by light response. A regulated circadian rhythm is important for a healthy life, whereas a disturbed circadian rhythm can lead to health issues such as insomnia and mood disorders. There has been a consensus that our circadian rhythm strongly responds to shorter wavelength light, corroborated in studies. Thus, manipulating the output light of LSCs to contain larger proportions of light with shorter wavelengths could enhance circadian regulation. LSC devices have the potential to transport sufficient daylight up to 5m deep into the building, achieving areas beyond the reach of windows. Thus, LSCs can serve as a tool for daylighting purposes, regulating circadian rhythm and providing sufficient light for comfortable indoor visibility.