Dynamically assessing life cycle energy consumption of buildings at a national scale by 2020 : an empirical study in China

Rapid urbanization and rising living standards in China have significantly increased building energy consumption, creating environmental pressures that necessitate the implementation of effective long-term energy-saving policies and plans. High-quality energy assessment plays a crucial role in developing these strategies. However, accurately assessing energy consumption on a national scale can be challenging due to the complex nature of energy systems and numerous potential influencing factors. This study aims to explore the internal interaction mechanism among energy-related factors from a macro perspective to improve the accuracy of energy consumption assessment. A national-level Integrated Dynamic Energy Assessment (IDEA) model is developed to reveal the potential linear and non-linear relationships in the macro energy system through system dynamics and the least squares method, and meanwhile to quantify the life cycle energy consumption of urban residential buildings in China from 2000 to 2020 accordingly. Results show 1) the five energy-related subsystems (population, economy, building, energy, and environment) achieved significant growth at least twice. 2) there are strong connections among them, as evidenced by multivariate linear and non-linear regression equations; 3) life cycle energy consumption of buildings has increased significantly over the last 20 years from 192.86 M tce to 1131.07 M tee, and the largest contributor is operational energy (45%), followed by embodied energy (33%) and mobile energy (22%) in 2020. 4) The discrepancies in end-uses of the operational energy indicate marked changes in occupants’ energy-use behaviours in recent years. This study provides not only a more precise interactive system for evaluating national-level energy consumption, but also detailed life cycle energy consumption and internal interconnection relationships that can assist China's energy policymaking and serve as a reference for other nations.