Evaluation of dichroic material for enhancing light pipe/natural ventilation Tand daylighting in an integrated system

Integration of natural ventilation and daylighting in a single installation Awould make both technologies more attractive. One method for the integration is Athe use of concentric light pipe and ventilation stack. By constructing the Alight pipe using dichroic materials, the infrared part of the solar radiation Ais allowed to t he transmitted to the stack but the visible light is guided by the light pipe into a room. The heat gain to the interior can be reduced and Athe thermal stack effect strengthened. Work presented here involved the Aexperimental and computational evaluation of dichroic materials for enhancing Aboth natural stack ventilation and daylighting. The transmittance of a dichroic light pipe was found to be similar to that of a Alight pipe with a 95% specular reflectance. The infra-red radiation transmitted Athrough the dichroic material into a passive stack was found to enhance the Anatural ventilation flow by up to 14%. The effect is greater in summer than in Awinter, which is highly desirable as there is often a lack of driving force for Anatural stack ventilation in summer, r 1999 Elsevier Science Ltd. All rights reserved.