# Space Efficiency of Tall Buildings in Singapore
## 4 Results
### Relation of Space Efficiency and Key Design Considerations
Mixed-use buildings (three in total) and the single hotel building using shear-walled frames show greater variability in space efficiency, reflecting the diverse functional and spatial requirements that such buildings must accommodate. Figure 11: Cases by material. Outrigger frame system, used in \(11\) buildings, also demonstrates varied space efficiencies across different building functions. Office buildings using this system (six in total) display a moderate range of space efficiencies from approximately 65% to 85%. The variability here may be due to the architectural flexibility that outrigger frames provide, allowing for large, open floor plans that are desirable in office environments but also possibly resulting in a less efficient use of space in some designs. Hotels (three in total) and mixed-use buildings (two in total) with outrigger frames show even broader ranges of space efficiency, suggesting that, while this system offers flexibility in architectural design, it may also lead to inefficiencies depending on how space is allocated and utilized within the building. The mega column system, represented by only three buildings, is primarily used in office structures (two in total) and one residential building. These buildings show a wide range of space efficiencies, indicating that, while the mega column system can support large spans and open spaces, making it suitable for office and other commercial uses, its impact on space efficiency can vary greatly depending on the specific design and configuration of the columns within the building's footprint. The shear-trussed frame is represented by a single office building, which shows a lower space efficiency of around 70%. This system's design, which incorporates trusses to provide structural support, may result in reduced usable floor space due to the physical space occupied by the trusses and their impact on internal layouts. Overall, the data show that the choice of structural system greatly impacts space efficiency in tall buildings. Shear-walled frames typically provide higher space efficiency, especially in residential buildings, due to their effective use of space and stability. Outrigger frames and mega column systems offer more architectural flexibility but vary more in efficiency because they are used in buildings with diverse needs and designs. Limited data on shear-trussed frames suggest they may face challenges in achieving high efficiency. These findings emphasize the need to match the structural system with the building's function and design goals to optimize space efficiency in tall buildings in Singapore. In conclusion, as seen in Figure 13, radar charts compare the spatial efficiency of different building types--residential, office, hotel, and mixed-use--based on core layouts, forms, structural systems, and materials. Residential buildings (green) exhibit high spatial efficiency, ranging from 80% to 90%, by utilizing central core layouts, prismatic forms, and shear-walled frame systems, optimizing both space and structural stability. Office buildings (blue) show efficiency between 70% and 85%, balancing central and peripheral core designs to accommodate flexible layouts, with prismatic forms and concrete for enhanced structural integrity. Hotel buildings (orange) demonstrate a broader range of spatial efficiency (60% to 90%) due to the inclusion of shared amenities and luxury spaces, though they continue to rely on central cores and shear-walled systems. Mixed-use buildings (grey) display the widest variation in efficiency, from 65% to nearly 100%, as they integrate various functions,  
Figure 12: Cases by system. utilizing both central and peripheral cores with prismatic forms and shear-walled frames. These charts illustrate how each building type optimizes spatial efficiency in high-rise structures, with values ranging from 68% to 91%, by adopting design strategies tailored to their functional and structural requirements.