Investigation of the relationship between depth of overhang and amount of daylight indicators in office buildings of Kerman city

The use of daylight in offices has become an effective strategy to improve the quality of indoor space and energy efficiency. There is enough potential to have daylight autonomy in Kerman as a city with more than 300 sunny days a year. Therefore, this study aimed to investigate the relationship
between facades configuration and the amount of daylight in office buildings of Kerman. This study was carried out based on the simulation in DesignBuilder software (DBS). In this study, 36 typical rooms, with the same physical characteristics (4 m×6 m×4 m), with window-to-wall ratio (WWR) between 10- 90% with four overhang depths (0, 0.5, 1 and 1.5 m) were modeled. Based on daylight utilization, the results indicate that an optimal WWR for a room with 1 m overhang depth ranged from 50% to 70%. Also, the room with 0.5 m overhang depth and without overhang, had suitable daylight while WWR was at least 50%, but the room with 1.5 m depth would not
encounter glare problem even when WWR was 90%. The results confirm that overhang depth and WWR have significant effect on daylight parameters such as daylight factor (DF), work plane illuminance (WPI), and WPI ratio. Hence, these insights can be useful for designers to design buildings with lower energy use and higher daylight
quality, when enough light is provided in office rooms