Visual and non-visual effects in micro-space luminous environments with visual display terminals

Working with visual display terminals (VDTs) is common in modern indoor spaces. It creates a distinct micro-space luminous environment, consisting of self-luminous screens and lighting backgrounds. However, integrative lighting, which considers both visual and non-visual effects of light, rarely focuses on such luminous environments. To address this gap, this study aims to explore the visual and non-visual effects in VDT luminous environments and how they are quantified at eye level. We conducted spectral simulations and laboratory experiments on various VDT lighting scenes and analyzed the illuminance and melanopic equivalent daylight illuminance (m-EDI) produced at eye level. Results show that the VDT luminous environment can be analyzed based on the light distribution of the vertical viewing plane where the VDT is located. Eye-level illuminance and m-EDI can vary by hundreds of lx depending on the screens and backgrounds in the VDT luminous environment. Despite the spatial distribution differences, both eye-level illuminance and m-EDI are linearly related to the averages of luminance and melanopic equivalent daylight luminance (m-EDL) of the VDT work plane, respectively. Additionally, the VDT screen has greater impacts on the eye-level illuminance and m-EDI compared to the lighting backgrounds that cover a larger area. The percentage of its contribution is exponentially related to the contrasts of the average screen-to-background luminance or m-EDL in the VDT luminous environment. These findings are expected to simplify and expedite the prediction of visual and non-visual effects and provide valuable insights for facilitating integrative lighting in VDT luminous environments.