Abstract: “This study evaluates the energy performance from the use of daylight through the window with horizontal slats installed between two glazing panes (slat window). Two mathematical models were validated with experiments and were adopted to determine the heat gain and the daylight transmission through the slat window under the tropical sky and climate. The results show that the daylight use from the slat window is energy efficient compared with the case of heat reflective glass that interior lighting is fully reliance on electric lamps. However, the daylighting through the slat window has to be implemented with care for shallow rooms with low values of required interior illuminance in order to avoid excessive heat gain to airconditioning system.”

Keywords: Daylighting,Slat window, Heat transmission, Tropical climate.