Effects of balconies on daylighting apartment buildings in context of Dhaka

Abstract

Daylighting is an essential passive strategy which helps to reduce the consumption of electricity or reliability on artificial lighting, and positively enhances wellbeing of building occupants. Inefficient design of buildings, surrounding conditions and presence of natural and manmade obstructions are often the main issues for inadequate daylighting inside the buildings. In addition, the topography, the geographical condition of the site and its regional conditions of weather have direct impact on interior daylight potential. Though inviting daylight in indoor space is a challenge, control of glare is vital in daylighting design. Balcony is a transition space which can invite glare free daylight in indoor space. By exploring balcony design, effective daylighting for interior space could be ensured. This research has examined the notable impact of balconies on daylighting performance of the balcony adjacent bedrooms of high-rise apartment buildings by using simulation program. Daylight simulation is performed by creating a virtual room with an attached balcony based on information from a real-world apartment building in Dhaka. 3D models are created for computer simulation to calculate the amount of daylight incident on a generated grid point on the work-plane. To generate realistic lighting levels, these models are then exported to RADIANCE Synthetic Imaging software and finally analyzed with DAYSIM simulation program for annual performance evaluation. The results reveal that the balcony patterns have a significant impact on daylight penetration to the adjacent interior space, as well as the indoor illuminance and luminance distribution. The balcony with 915mm railing height with a drop ended at 2150mm from finished floor level is found to be the most practicable configuration for daylight penetration among the studied configurations. Based on the findings of simulation studies sliding glass openings with a light shelf outer depth equal to balcony depth and an internal depth of 500mm performs better compared to only punched or sliding door on the adjacent wall to the balcony. It is also discovered that when balconies are placed one above another in each floor outperforms the type when balconies are placed in zig-zag pattern on building elevation. After finding the best balcony depth 1370mm, the floor and facade materials were discovered to be silver glossy tiles flooring (reflectance 90) and blue color (reflectance 20) indoor walls. Finally, when these are taken into account, the recessed balcony outperforms over cantilever and semi-recessed balcony types. The study emphasizes the performance of daylight in indoor spaces by altering balcony features design, while also providing a basic framework for judging daylight design principles.

Keywords Balcony Design, Daylighting, Dhaka City, Facade Treatment, Glare, Apartments, Computer Simulation, Light Shelf.