Life cycle energy consumption and CO2 emission of an office building in China

Building is one of the main factors of energy use and greenhouse gas emissions. Reducing energy consumption and carbon dioxide (CO2) emission from building is urgent for environmental protection and sustainable development. The objective of this study is to develop a life cycle assessment (LCA) model for an office building in China to assess its energy consumption and CO2 emission, determine the whole life cycle phases, and the significant environmental aspects that contribute most to the impact. A process-based LCA has been used to identify and quantify the energy consumption and CO2 emission of the office building. The LCA is conducted in accordance with the Environmental Protection Agency, The Society of Environmental Toxicology and Chemistry, and the International Organization for Standardization standards for life cycle assessments. The entire life cycle including building materials production, construction, operation, and demolition of the building is studied. A service life of 50 years is assumed and the major construction materials such as concrete, cement, brick, steel, timber, glass, and plastic are selected for the building. The results show that building operation uses the largest share of energy and contributes most to CO2 emission. The cooling and heating system in building operation strongly influence the energy consumption and CO2 emission of the building. In addition, the large quantity use of concrete and steel in materials production, and the treatment of end-of-life building materials are also the important aspects impacting the environmental performance of the building. Based on the results of the study, some environmental improvements aiming at reducing energy consumption and CO2 emission throughout the life cycle of the building are provided. This study provides an LCA of the energy consumption and CO2 emission of a typical office building in China. It determines the whole life cycle phases that contribute most to the impact and defines the significant environmental aspects of the building. This study also shows the importance of using a life cycle perspective when evaluating energy consumption and CO2 emission of building and also lays the groundwork for LCA studying of other office buildings in China.