The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design

摘要

Recently, corneal illuminance attracts much attention because it is closely related to important functions of indoor lighting. Especially, applying circadian light in the built environment places a challenging requirement on indirect corneal illuminance. In this work, rule-of-thumb equations are proposed to guide circadian lighting design: (i) for artificial lighting, E-cor,E-avg ((i)) = (Phi/C-1). rho/(1-rho'), where E-cor,E-avg (i) is the average indirect corneal illuminance at standing or sitting positions, Phi is the initial flux from luminaires, C-1 is a constant comparable to the total room surface area, rho is the reflectance of the surface where the first reflection occurs, and rho' is the area weighted average of surface reflectance; and (ii) for daylighting, E-cor,E-avg (i) = C-2 . WWR . rho/(1-rho'), where C-2 is a constant, and WWR represents the window-to-wall ratio.