Spatial Optimization of Informal Learning Spaces in University Libraries: A Multi-Coupling Framework and Empirical Analysis from Lanzhou, China

The transformation of university libraries into learning commons has highlighted the importance of informal learning spaces (ILSs). However, the mechanisms through which spatial elements influence learning experiences remain underexplored, particularly in western China. Drawing on person-environment fit theory and a multi-coupling framework, this study develops a four-dimensional analytical model comprising spatial layout, facility configuration, environmental quality, and cultural perception. A mixed-methods approach was employed, including 532 valid questionnaires, behavioral observations, and comprehensive environmental measurements (illuminance, noise, CO2, PM2.5, TVOC, thermal conditions) across three university libraries in Lanzhou, China. Structural equation modeling (SEM) and coupling coordination degree modeling were used for analysis. Spatial layout (β = 0.324, p < 0.001), facility configuration (β = 0.287, p < 0.001), environmental quality (β = 0.196, p < 0.01), and cultural perception (β = 0.158, p < 0.05) all significantly predicted learning satisfaction, jointly explaining 67.3% of the variance. Learning satisfaction partially mediated the relationship between spatial elements and learning outcomes (indirect effect 31.2%). Coupling coordination degrees ranged from 0.578 to 0.634, revealing a “high coupling, low coordination” pattern, with cultural perception as the common shortfall. Environmental measurements showed CO2 concentrations ranging from 823 to 946 ppm in quiet zones and up to 1085 ppm in lounge areas, correlating negatively with satisfaction (r = –0.41, p < 0.05). Spatial elements influence learning outcomes primarily through satisfaction enhancement. An integrated optimization framework is proposed, offering actionable strategies for ILS design in similar contexts.