Taking the Time Characteristic into Account of Life Cycle Assessment: Method and Application for Buildings

Life cycle assessment (LCA) involves many temporal issues. It is necessary to make a clear distinction between long-term impacts and short-term impacts, especially for those structures with long service life, such as buildings. With their long service life of 50 years, a great deal of maintenance and repairs could be conducted, causing a respective environmental impact. In this paper we explored a monetization method to convert the life cycle environmental impact into a life cycle environmental cost to address the temporal issues involved in LCA by discounting. This method can facilitate decision-making when tradeoffs between current and future environmental impacts exist. Moreover, this method can be used as an effective supplement to life cycle cost and provide decision support for making trade-off between cost and environmental impact. Finally, a building located in Xiamen City, China was selected as a case study and analyzed by the proposal LCA method. The results indicated that carbon cost in the operational stage is the maximum, building material production and transportation stages are ranked second, and the amount in the demolition stage is negligible, compared with the other three stages. Additionally, with the increase of the discount rate, the carbon cost in different life cycle stages will decrease, the percentage of the carbon cost in the operational stage will gradually decrease, but the percentage of the carbon cost in building material production and transportation stages will gradually increase.