In the quest for optimal indoor lighting, researchers have long grappled with the complexities of daylighting performance. A recent study published in the Journal of Daylighting, translated from Arabic as ‘Journal of Daylight’, sheds new light on how to balance multiple criteria for daylighting in indoor spaces, particularly in sub-tropical regions. The research, led by Ali Ahmed Bahdad from the Interior Design Department at the University of Prince Mugrin in Saudi Arabia, delves into the intricacies of switchable slat insulated shades and their impact on daylighting performance.
Bahdad’s study focuses on a specific type of glazed system: Insulated Glazed Units with Parallel Slat Transparent Insulation Materials (IGUs/PS-TIMs). These systems are designed to enhance daylighting availability while improving thermal and visual comfort in office buildings. The research employs a sophisticated framework of multi-objective optimization (MOO) and statistical analyses to identify the most influential objective weights and useful daylighting illuminance (UDI) thresholds.
The study’s innovative approach involves a two-step process. First, a multi-objective optimization based on statistical analysis ranks the UDI threshold control setpoint and critical objective weights. In the second step, the optimal UDI thresholds and critical objective weights are further refined for final ranking solutions. This method allows for a nuanced understanding of how different objectives and thresholds impact the optimized parameters of IGUs/PS-TIMs.
One of the key findings is the significance of prioritizing certain objective weights in the ranking of final solutions based on the best UDI thresholds. “When considering the priority of critical objective weights in ranking final solutions based on best UDI thresholds, different schemes can be obtained, which is of great significance to the early design stage of buildings,” Bahdad explains. This insight is crucial for architects and engineers aiming to design energy-efficient buildings that maximize natural light.
The research identifies UDI, Annual Sunlight Exposure (ASE), and Quality of View (QV) as the most critical objective weights. The study found that the UDI500-2000lux threshold significantly improves UDI and ASE in all optimal cases compared to the UDI500-1000lux/50% threshold. Specifically, the total average percentage of UDI improved between 22.63% to 27.80%, and ASE improved between 2.14% to 11.52%. For QV, the UDI500-1000lux/50% threshold slightly improved QV by 1.16% and 10.56%.
These findings have significant implications for the energy sector. By optimizing daylighting performance, buildings can reduce their reliance on artificial lighting, leading to substantial energy savings. This is particularly relevant in sub-tropical climates, where the balance between natural light and thermal comfort is crucial.
The study’s methodology and results provide a roadmap for future developments in the field. As Bahdad notes, “These two pairs of UDI thresholds with given priority to UDI, ASE, and QV as critical objective weights are suggested as the most appropriate conflicting objectives for optimizing daylight under sub-tropical climate conditions.” This insight can guide the design of more efficient and comfortable indoor environments, benefiting both occupants and the energy sector.
As the construction industry continues to evolve, research like Bahdad’s will play a pivotal role in shaping the future of building design. By leveraging advanced statistical methods and multi-objective optimization, architects and engineers can create spaces that are not only energy-efficient but also visually and thermally comfortable. The insights from this study, published in the Journal of Daylighting, offer a glimpse into the future of daylighting performance and its potential to revolutionize the way we design and build our indoor spaces.
