Abstract

Utilisation of daylight in buildings may result in significant savings in electricity consumption for lighting while creating a higher quality indoor environment. Additional energy savings are also realised during the cooling season, when reduction of internal heat gains due to electric lighting results in a corresponding reduction of cooling energy consumption. This study presents a simulation of an office space with an advanced window with integrated motorized venetian blinds between the panes. The methodology developed consists of the following steps: (1) The transmittance characteristics of the window with the shading device are determined as a function of blind till angle, solar incidence angle and sky conditions. (2) The illuminance distribution on the work plane due to daylight is determined. (3) The electrical light level required to achieve the necessary total illuminance level on the work plane is computed and light dimming levels are established. (4) Energy savings from reduced utilisation of electric lights are estimated