A study on a combined light pipe and solar-heated ventilation stack

Abstract

A theoretical and experimental study has been made of the performance of a vertical light pipe of height
3 m and cross-section area 0.0625 m2 surrounded by an air duct of total cross-section area 0.23 m2 above a room
of height 3.8 m and fl oor area 9 m2. Heat transfer from the hot water jacket to the air duct is assisted by stainless
steel fi ns. The ventilation of the room, due partly to the buoyancy of the air in the duct and partly to the wind
effect, amounted to nearly 10 air changes per hour. The light pipe has specular refl ecting walls. It was found that
the transmission of daylight through the light pipe in the middle of a partly cloudy day varied in the range 56-84%.