Performance of air-clad optical rod daylighting system

J M Callow and L Shao, Institute of Building Technology, University of Nottingham, UK

Keywords

daylighting, light rods, energy efficiency, optical rod, building services

Abstract

A daylighting system is investigated in which a set of ‘light rods’ is used to transport light from the exterior of a building into areas of low illuminance within the building. With a 50mm diameter, these rods are sufficiently small to be fitted into most existing buildings without significant structural modification. During testing, rods were found to have a transmittance equal to or greater than that of a light pipe that had aspect ratio at least 2.5 times smaller. Losses due to angled entry of light were investigated and it was found that the air cladding had given rise to a rod of large numerical aperture. Rods would collect both direct and diffuse light throughout the year, at high efficiency and could be used for desk-level task lighting. Benefits of installation would include the reduction of pollution and expense associated with the use of electric lights and greater occupant well-being.