Gen-Z students' learning styles have recently changed significantly due to inquiry-based learning and rapid information technology development. Physical libraries have to surrender bookshelves to learning commons to attract student visits. This study analyses the effectiveness of the learning commons at the Hong Kong University of Science and Technology (HKUSTLC) as a case of the library as a third space based on the third space theory of Oldenburg through using the 5Es usability model (effective, efficient, engaging, error tolerant, easy to learn) based on its publication, website information, and email inquiries with its manager. These finding indicate that HKUSTLC has been well-received, effective, efficient, and attractive. Yet, based on the limitations and shortcomings, the authors suggest solutions regarding activity delivery, space re-engineering, regular feedback collection, and environmental improvements. This study also provides insights for constructing learning commons in physical libraries as a third space for Gen Z students, which scant studies have covered, especially in Asia.