Daylighting through external vertical slats on east windowed fa?ade in a tropical climate

In the tropics, daylighting from a side window requires shading to intercept direct sunlight from the window whilst allowing penetration of daylight from sky. In this paper, daylighting from external vertical slats was investigated for which they are equipped on east-facing window of a room. Full-scale experiments and simulations were conducted to characterize distribution of the interior daylight from the slat window under a real tropical climate. Performance of the slat window was evaluated in terms of the "Useful daylight illuminance" (UDI), interior daylight availability and light power density (LPD) of an integrated dimmable lighting system. Using our tropical records of daylight illuminance, the simulation results show that altering properly the tilted angle of the vertical slats with the same configuration as that of the experimental room can improve the interior daylight illuminance and distribution and can save about 75% of electric energy from dimmable lighting.