Climate change mitigation has become a central objective of global sustainability policies, with net-zero CO₂ emissions widely recognized as a critical pathway. Urban areas contribute substantially to CO₂ emissions, particularly through building construction and urban renewal. Land-use regulation, especially floor area ratio (FAR), plays a key role in shaping development intensity and building form, yet its carbon implications remain insufficiently examined.This study analyzes construction-phase CO₂ emissions under FAR-based redevelopment scenarios using Wanhua District in Taipei City as a case study. Emissions from existing buildings are compared with redevelopment scenarios that comply with statutory FAR and intensified development conditions. The results show that redevelopment outcomes vary across development intensity scenarios: statutory FAR redevelopment may reduce emissions in some cases, whereas higher FAR development leads to substantial increases in embodied CO₂ emissions due to increased density and reinforced concrete construction.The findings reveal a clear trade-off between urban renewal and CO₂ mitigation and highlight the importance of adopting statutory FAR as a baseline for CO₂ emission accounting to support sustainable urban renewal under net-zero targets.