Optimising indoor lighting condition for visual comfort via light pipes in design of Kada-city shopping mall

Abstract

With increasing cost of electricity and epileptic state of electricity supply in Nigeria, it has become a necessity to harness day lighting in shopping malls, but with the advantages of daylight follows the problems of inadequate placements of openings, which brings about overheating, under-lighting, over-lighting and glare which makes planning of buildings so that daylight could enter interior spaces a huge problem. The aim of this study is to determine the optimum diameter of light pipe for a daylighting of shopping malls in Kaduna metropolis with the view of designing Kada city shopping mall using its findings. Qualitative research methods were employed using computer simulation software using climate data gotten from meteorological data sets. Results showed that the quantity of day lighting is affected by a change in diameter of light pipe. An 85% increase in average lux levels from 794.4 lux at no light pipes to the 1469.2 lux at 450mm diameter light pipe with a 36% increase in Daylight autonomy (DA) from 37% at no light pipe to 73.2% at 300mm diameter light pipe. In conclusion, 300mm diameter of light pipe was found to be the optimum diameter for adequate lighting of shopping malls in tropical climates of Nigeria. Due inadequate values (below 60%) together with UDI values were observed in all the simulation models with light pipe diameters below 300mm, it is recommended that designers should use 300mm diameter light pipes in every 12m² area.