# Space Efficiency of Tall Buildings in Singapore
## 1 Introduction
Economically, tall buildings are a strategic response to Singapore's land scarcity and the need to accommodate a growing population and vibrant business community within a limited area [28; 29; 30]. Skyscrapers serve as multifunctional hubs that combine residential, commercial, and recreational spaces, fostering economic activity and enhancing urban efficiency. The economic viability of tall buildings in Singapore is further bolstered by the city-state's status as a global financial center, which attracts significant investment in high-quality office spaces and luxury residences [31; 32; 33]. Technologically, Singapore's tall buildings benefit from cutting-edge advancements in smart building systems and digital technologies [34; 35; 36]. From energy-efficient HVAC systems to integrated building management systems that optimize energy use and enhance occupant comfort, technology plays a significant role in increasing the performance and sustainability of tall buildings [37; 38; 39]. The CapitaGreen building, for example, utilizes a unique double-skin facade and energy-efficient systems to reduce energy consumption by up to 26%, demonstrating the potential of technology to drive sustainability in high-rise developments [40]. In recent years, sustainability has become a key focus in the development of tall buildings in Singapore [41; 42; 43]. As one of the most densely populated cities globally, Singapore faces unique challenges related to land use, energy consumption, and environmental impact [44; 45; 46]. The emphasis on green building practices and sustainable design has led to the widespread adoption of energy-efficient systems, water conservation measures, and the use of sustainable materials in the construction of tall buildings. The concept of space efficiency is particularly crucial in Singapore, where maximizing the use of limited land resources is not just an option but a necessity. The efficient use of space in tall buildings allows for a greater concentration of services and amenities within limited land, reducing the need for urban sprawl and preserving green spaces. Additionally, space efficiency enhances the adaptability and functionality of buildings, enabling them to meet diverse and changing needs over time. Mixed-use developments like One Raffles Place [47] and the Duo Complex [48] exemplify this approach, combining office spaces, residential units, hotels, and retail spaces within single, compact footprints. There is currently a limited amount of research on the efficient utilization of space within Singapore high-rise buildings. This article will bridge this gap by examining 63 cases. The key focus is to detect the essential architectural and structural factors that influence spatial efficiency. The assessment delves into different aspects such as function, form, core layout, load-bearing systems, and materials, evaluating their effects on space usage. The findings offer valuable insights for construction professionals, particularly architects, to support informed decision-making in the development of tall buildings in Singapore. This paper is dedicated exclusively to spatial efficiency, deliberately setting aside aspects of sustainable design such as energy efficiency, resilience, and disaster preparedness. This decision is due to the inadequate data on these factors across the case studies, which limits the ability to perform a comprehensive assessment. By focusing on spatial use alone, this research will provide a more accurate and in-depth analysis of this specific attribute, avoiding the complexities associated with the lack of sufficient data on sustainability. The cultural and regional practices that might influence architectural choices were set aside due to the lack of quantifiable data linking them directly to spatial efficiency.