An accurate daylighting simulation can potentially improve the quality of pre-planing buildings and regulating daylighting to achieve the goal of green buildings. However, standard sky models can hardly reproduce real skies in real-time for a specific location within its micro-climate. This paper investigates an embedded photometric device based on high dynamic range (HDR) sky luminance monitoring with high resolution mapping in simulating real-time horizontal work-plane illuminance distribution. To increase time efficiency in the iterative process for the illuminance calculation, a matrix algebraic approach was employed and adapted for the device. The photometric device was validated experimentally in a daylighting test module with external Venetian blinds at different tilt angle of slats. The results indicate the embedded photometric device based on monitored sky can improve accuracy in simulating real-time daylighting provision by over 3 times, with 15%∼37% average error, compared with a common practice using the Perez all-weather model.