Assessing effects of future climate change on outdoor thermal stress and building energy performance in severe cold region of China

Future climate change is poised to affect the urban thermal environment and building energy performance in the severe cold region, yet its full impact remains unclear, particularly concerning extreme weather events. This study proposes a multi-scale climate-energy framework to assess the future climate's influence on outdoor thermal stress and building energy efficiency under Shared Socioeconomic Pathways for 2050 and 2080 in this region, using Harbin serving as a case study. The framework also evaluates the adaptation potential of trees and natural ventilation. The results showed that climate change may narrow the physiologically equivalent temperature (PET) range in summer daytime, and increase unacceptable heat exposure duration from 2 h to 7-8 h by 2050 and further to 5-10 h by 2080. While the overall annual building energy demands are expected to increase minimally (<12 %), cooling loads could rise substantially. Trees show diminishing returns in reducing peak PET as climate severity increases, yet can moderately reduce total energy demand (4-6 %) and peak demand (4-5 %) during extreme warm days. The energy-saving potential of natural ventilation is projected to decline, with a potential decrease of up to 40 % by 2080 in the most severe scenario. This study provides new insights into how future climate change could impact outdoor comfort and building energy in the severe cold region, and offers a versatile framework for urban sustainability planning that can be applied to other cities and climates.