# Space Efficiency in European High-Rise Timber Buildings
## 4 Discussion  
This article aims to thoroughly compile and integrate extensive data from 56 tall timber buildings across Europe, centering on spatial efficiency, specifically examining the architectural and structural aspects of these ecologically sustainable towers. By doing so, we aim to deepen the understanding of the intricate processes involved in the design and development of high-rise timber edifices. Overall, this study seeks to significantly contribute to the current body of literature in the global and European context of designing and constructing these sustainable buildings. The results have both parallels and differences when compared to earlier research endeavors, as exemplified by the research [36]. Prominent studies presented highlight distinct approaches and findings in high-rise construction, focusing on timber and composite materials. Tall timber buildings, as supported by study [37], emphasize a centralized core design that enhances structural robustness, integrates circulation efficiently, and fosters architectural adaptability. These buildings typically employ straightforward rectangular layouts that streamline construction and optimize space utilization, reflecting traditional practices and modular construction principles. In contrast, the trend in Europe towards composite materials (notably discussed in [75]) combines timber's aesthetic appeal with concrete's strength, particularly favoring shear-walled frames for stability against horizontal forces. Both studies stress the importance of space efficiency, with non-timber high-rises averaging 71% to 76% efficiency and varying core area-to-GFA ratios, whereas timber constructions, especially in Finland and other studies, achieve higher efficiencies ranging from 70% to 95%. In tall timber buildings, the predominant arrangement often features a centralized core design, supported by various studies such as [33]. This layout, accommodating main vertical circulation elements, provides several benefits. It enhances structural robustness, expands floor area by integrating circulation and service purposes, and promotes efficient vertical movement, mitigating congestion. Moreover, it fosters architectural adaptability,  
Figure 10: Inter-relationship between space efficiency and structural system. specifically useful in multi-use projects. The majority of structures examined in this research exhibit a straightforward rectangular design, favored for its simplicity compared to more intricate shapes. Rectangular layouts align well with traditional building practices, streamlining the building process. Their floor plans efficiently utilize space and simplify room configurations. Additionally, their modular nature advances sustainable and cost-efficient construction by optimizing materials and resources. An observable shift in high-rise construction across Europe involves the increasing adoption of composite materials combining timber and concrete, evolving as the favored option due to their adaptability and myriad advantages [75]. This blend harnesses the cozy charm of timber with the robustness and adaptability of concrete [76; 77]. Within the structural frameworks of timber constructions, a distinct ranking has surfaced, wherein lofty timber endeavors lean towards shear-walled frames and shear-wall arrangements for their adept management of horizontal forces and assurance of steadiness, principally in confronting wind and earthquake impacts. A suggested criterion to assess the space efficiency of high-rise structures is a target level of 75% [78]. Studies on non- timber high-rise buildings intended for office, residential, and mixed-use functions revealed various levels of space optimization, generally ranging from 71% to 76% [22; 23; 24]. These evaluations highlight differences in the proportion of core area to GFA, ranging from 19% to 26%. Regarding office towers, the lowest recorded space utilization was 63%, whereas the highest was 82%. Likewise, the core area-to-GFA ratio varied from the lowest of 15% to the highest of 36%.