Environmental impacts of short building lifespans in China considering time value

China has about 60 billion m2 of existing buildings, with approximately 2 billion m2 newly constructed each year. This accounts for half of all new buildings globally. A large number of buildings were demolished during the urban renewal process in China, significantly reducing the average lifespan of buildings and wasting vast amounts of energy and resources. However, the corresponding environmental impacts of reduced building lifespans have not been studied. Moreover, how to accurately evaluate future environmental impacts of construction projects is still a difficult problem, since in some cases the environmental impacts may not be realized for many years. In order to investigate the relationship between building lifespans and the corresponding environmental impacts, this paper first estimated the average lifespan of buildings in China through literature review, field investigation and calculation (using survival rate and demolition rate, respectively), revealing that the average building lifespan in China is from 25 to 35 years which is far shorter than the designed lifespans of buildings in China. It is also much shorter compared to the building lifespans in ten developed countries. Six buildings in Hebei Province in China were selected as case studies to conduct life cycle environmental (LCE) impact assessment. The results of the case studies indicate that (1) extending the building's lifespan from 30 to 50 years would reduce 40% of its total LCE impacts; (2) the environmental impacts caused by buildings (per area per year) in China is 2.3 times than that in the UK; (3) when environmental impacts are considered over time, they would decrease dramatically with the increase of discount rate, indicating that the buildings in developed cities in China with higher discount rates are more sensitive to environmental degradation.