Sustainable urban greening in cold cities: A multi-objective framework for energy savings, emission reduction, and cost optimization

The building sector contributes to over 30% of global energy consumption and carbon emissions, making it a critical driver of climate change and economic risks. In response, there is a growing need for integrated assessments that consider energy savings, carbon reduction, and cost-effectiveness, particularly in the context of developing countries. Given the high sensitivity of residential buildings to environmental factors and the financial constraints of urban development, this study aims to identify the optimal urban green coverage ratio (GCR) over the building life cycle in cold-climate cities. A multi-objective optimization model was developed to integrate energy efficiency improvement, carbon emission reduction, and economic feasibility into urban greening strategies and building configurations. The Integrated Benefit Assessment Model (IBAM) combines simulation outputs from ENVI-met and EnergyPlus to evaluate different scenarios systematically. The results show that buildings oriented along the East and West (E&W) and Southeast and Northwest (SE&NW) directions achieve higher energy savings, while a South and North (S&N) orientation with a GCR of 20–30% yields the best overall benefit. Sensitivity analyses using Morris, Partial Rank Correlation Coefficient (PRCC), and Sobol methods identified GCR and initial cost (C1) as the most influential factors affecting the integrated outcomes. This study offers actionable insights for urban planners and policymakers, providing a strategic approach to balance environmental sustainability and economic feasibility. By aligning greening strategies with building configurations, it highlights the transformative role of urban greening in mitigating global warming and promoting sustainable urban development in cold-climate regions.