Improving daylight performance of light-wells in buildings with restricted land (Case study: mid-rise residential buildings in Urmia)

Nowadays, population growth in big cities and the High price of urban land have led to the construction of multi-story buildings. An important issue of architectural design in these buildings is to provide adequate daylight for all spaces. Light-well is a solution that is widely used in these buildings but due to the land constraints, they usually lack proper daylight performance especially in high latitudes. The main purpose of this study is to investigate the effect of different light-well form (vertical and horizontal section shape) with the constant area on all floors on its daylight performance. The selected case study is Urmia located at latitude 37.5. The model is a building with a 4-story light-well in Urmia. The alternatives were evaluated using grasshopper/rhino for parametric simulation, ladybug for inputting time zones and delivering sun position coordinates, and honeybee for analyzing daylight. In this study, the effect of light well form on its performance was investigated using the Useful Daylight Illuminance index. The results show that east-west rectangular light-wells perform the best among vertical light-wells. In all cases, light-wells with sloping walls improve daylight performance, and light-wells with inclined walls to the south reduce lighting efficiency. The light-well form does not significantly change the daylight performance in the upper floors, but it is significantly more effective in the lower floors. As a result, the east-west orientation for the horizontal section and the upward opening vertical section improve daylight performance and increase Useful Daylight Illuminance by 15-20%.