Lighting design based around human sense of space brightness

We aim to create a more pleasant and fulfilling lighting environment that also saves energy through highly efficient lighting design. We also aim for effective incorporation of increasingly diverse light sources, including indirect and architectural lighting. This endeavor requires a benchmark other than the one conventionally used. As shown in the diagram, the unit “lux” (symbol: “lx”) is used to measure illuminance (objective brightness of a planar surface) and indicates the amount of light illuminating a surface (i.e. a part of the architectural environment such as a floor or desktop), but it does not accurately convey the way the human eye perceives brightness. Meanwhile, luminance measures the total amount of light emitted from surfaces including reflections, etc., and a very different reading is taken depending on whether the surface in question is white or black, just as the human eye perceives a white surface as much brighter than a black one. Focusing on measuring luminance, and delving into emotional and psychological aspects as well, we sought to express human sense of brightness quantitatively and bind lighting, architectural spaces, and their human inhabitants in one seamless whole. The result of this endeavor is the “Feu” index of the human sense of space brightness.
Application of this index enables design of the atmosphere of a space based on quantitative measurement. This new approach, “lighting design based around human sense of brightness,” is the idea behind SmartArchi.