Lighting Performance Analysis Inside a Building Using Tubular Daylight Guidance System with a Dome Collector Mounted on Tapered Neck Mirror Light Pipe

A tubular daylight guidance system (TDGS) effectively transports natural sunlight into the building interiors. It mainly consists of three parts viz. daylight collector, light-guiding tube with mirror lining on the interior surface also called mirror light pipe (MLP), and a diffuser. The system is passive, i.e. there are no tracking devices. In this paper, two configurations of TDGS setups consisting of a hemispherical transparent dome as daylight collectors integrated with six-meter-long cylindrical MLP and cylindrical MLP with a tapered neck were simulated for their lighting performance in a building. Simulation studies were performed using the lighting software tool Tracepro. The photometric analysis was done separately under direct components of sunlight and diffuse skylight for various timings on 21 June and 21 December. Results indicated that the lighting performance of the proposed design configuration having cylindrical MLP with a tapered neck was significantly enhanced on 21 December in comparison to the conventional daylight collector set up by more than ~50%. The lighting performance was similar to the conventional cylindrical MLP system on 21 June, and there was no compromise in the lighting levels for the desired visual performance for most of the day.