# Space Efficiency in European High-Rise Timber Buildings
## 1 Introduction
Residential buildings constructed from timber not only leverage its renewable nature and carbon sequestration capabilities but also promote a healthier indoor environment for occupants. Wood's natural thermal insulation properties contribute to reduced energy consumption for heating and cooling, thereby lowering carbon emissions associated with building operation. Moreover, the aesthetic and psychological benefits of wood in residential settings foster a connection with nature, promoting mental well-being and sustainable living practices among residents. By choosing timber for residential construction, stakeholders not only support sustainable forestry practices but also contribute to mitigating climate change, improving indoor comfort, and enhancing overall quality of life in urban environments. This holistic approach underscores the pivotal role of residential wood construction in advancing both environmental sustainability and human-centric design principles. In timber construction, architectural and structural considerations are crucial in the development of high-rise edifices. Among these factors, space efficiency is particularly crucial for optimizing the usable area to boost their economic attractiveness [22; 23]. Despite its significance, there is limited academic research delving into the spatial efficiency of such edifices [22]. Furthermore, despite thorough study being carried out on the technical, ecological, and economic dimensions of wooden structures (e.g., [24; 25; 26; 27; 28; 29]), there is a significant lack of focus on spatial efficiency within the European context. This discrepancy underscores the need for additional studies focused on improving space utilization in tall timber buildings while balancing design, financial, and ecological considerations. These studies would enhance understanding in the area and offer crucial visions for especially architects and contractors aiming to create more effective wooden buildings in Europe [30; 31; 32; 33; 34; 35]. Additionally, this research can inform building regulations and standards, ensuring that timber buildings meet safety, durability, and performance requirements while fostering innovation in European architectural design and construction practices. In research on spatial efficiency in buildings, [PERSON] and [PERSON] [36] and [PERSON] and [PERSON] [37] focused on wooden residential and office buildings, finding average efficiencies 83% and 88%, respectively. [PERSON] and [PERSON] [38] analyzed the spatial effectiveness of 55 mid-rise timber buildings in Finland, discovering efficiencies between 78% and 88%. [PERSON] [22; 23; 24] studied skyscrapers of various functions--office, residential, and mixed-use--and forms and found a common utilization of outriggered frame systems and central cores, with an inverse correlation between tower height and spatial efficiency. [PERSON] and [PERSON] [39] and [PERSON] [40] examined the space efficiency in prismatic and tapered tall buildings and it was revealed that the average space efficiency in both formswas 72%. [PERSON] [41; 42] focused on skyscrapers in different contexts including Asia and the Middle East in terms of space efficiency and found that average space efficiencies were 67.5% and 75.5%, respectively. [PERSON] and [PERSON] [43] performed a simulation for spatial effectiveness in 11 freeform high-rise office buildings, identifying structural design as a significant factor, with conical shapes achieving the highest efficiency. [PERSON] et al. [44] assessed spatial usage in Kabul's residential structures, spotting deviations from norms due to substandard interior planning and insufficient regulatory supervision. [PERSON] and [PERSON] [45] examined the impact of cutting-edge technologies on high-density urban areas, demonstrating a two- to threefold enhancement in spatial efficiency over traditional configurations. [PERSON] et al. [46] discovered that positioning homes at corners enhances land efficiency in detached residences in Sudan.