Impact of windows for daylighting on thermal comfort in architecture design studios in Dhaka

Abstract

Despite the fact that students work and perform better under natural lighting condition, observation shows that most of the architecture design studios in Dhaka are often lit by artificial means and the condition of daylighting is hardly satisfactory. Though artificial light can satisfy visual needs of the students and studio guides, it may cause tiresome and exhausting after a time period. On the other hand, entrance of direct solar radiation for daylighting in the studios can cause overheating, resulting in thermal discomfort with increased cooling loads. Both artificial lighting and overheating situation not only fails to provide the desired environment for teaching-learning in the studio, but also at the same time create pressure on the overall national energy demand. Proper daylighting and thermal strategies should be taken into account during planning and construction of the studios. As windows have a large-scale impact on daylighting and thermal comfort considering its size orientation and shading configuration, as well as on the energy consumption of the building, it is thus necessary to optimize window design for maximum benefit. This research aims to find out an effective window category from available window configurations of existing architecture design studios, located in Dhaka through simulation studies and investigates the effectiveness of the window configurations to enhance the visual and thermal quality of design studios. To start with, a literature review and field survey were conducted to get the knowledge base and to select available different window configurations for the simulation study. Then a case studio was selected and a dynamic annual Climate-Based Daylight Modeling (CBDM) method considering all weather sky luminance model (i.e. DAYSIM), was used to evaluate the performance of different window configurations installing at the case studio. Additionally, thermal simulation was done by EnergyPlusTM considering four output variables for measuring Predicted Percentage of Dissatisfied (PPD). Finally, daylighting and thermal results were combined to find out the most effective available window configuration for architecture design studios in climatic context of Dhaka. This research addresses the conflict between balancing visual and thermal comfort of the distinctive architectural featured windows. Results indicate that, segregated viewing window as the most feasible window configuration from the combined result of thermal and dynamic daylight simulation for architecture design studios. Furthermore, window-to-wall ratio of 22%-31% and 450mm horizontal shading device on south façade were found to be most effective in designing window. It is expected that the outcome of this research will help architects and designers to generate some guidelines for window configurations to improve the luminous and thermal environment of architecture design studios in Dhaka as well as in the other cities of Bangladesh.