Carbon Footprint Analysis of Buildings Based on LCA Theory Under Carbon Neutrality Goals:Taking the 3rd China International Solar Decathlon Competition as an Example

This paper focuses on the design of residential buildings oriented to the efficient use of solar energy,and selects the entries HUI HOUSE of Hefei University of Technology and Lille I University of France in the 3rd China International Solar Decathlon China Competition,based on the theory of the life cycle assessment(LCA)of buildings,and analyzes the carbon footprint from four aspects:building materials production and transportation stage,building construction stage,building operation stage,and building demolition stage.Through the calculation of the carbon footprint of buildings,the socio-economic benefits of HUI HOUSE in carbon reduction were analyzed;the result of the calculation was that HUI HOUSE achieved carbon neutrality in the ninth year,and continued carbon reduction after that,contributing a cumulative total of 947.54 tons of carbon negative in the life cycle of buildings.

建筑全生命周期碳排放——内涵、计算和减量

The life-cycle assessment method,which originates from general products and services,has gradually come to be applied to investigations of the life-cycle carbon emissions(LCCE)of buildings.A literature review was conducted to clarify LCCE implications,calculations,and reductions in the context of buildings.A total of 826 global building carbon emission calculation cases were obtained from 161 studies based on the framework of the building life-cycle stage division stipulated by ISO 21930 and the basic principles of the emission factor(EF)approach.The carbon emission calculation methods and results are discussed herein,based on the modules of production,construction,use,end-of-life,and supplementary benefits.According to the hotspot distribution of a building’s carbon emissions,carbon reduction strategies are classified into six groups for technical content and benefits analysis,including reducing the activity data pertaining to building materials and energy,reducing the carbon EFs of the building materials and energy,and exploiting the advantages of supplementary benefits.The research gaps and challenges in current building LCCE studies are summarized in terms of research goals and ideas,calculation methods,basic parameters,and carbon reduction strategies;development suggestions are also proposed.

Bayesian optimization+XGBoost based life cycle carbon emission prediction for residential buildings—An example from Chengdu,China

The large amount of carbon emissions generated by buildings during their life cycle greatly impacts the environment and poses a considerable challenge to China’s carbon reduction efforts.The building design phase has the most significant potential to reduce building life-cycle carbon emissions(LCCO_(2)).However,the lack of detailed inventory data at the design stage makes calculating a building’s LCCO_(2) very difficult and complex.Therefore,accurate prediction of building LCCO_(2) at the design stage using relevant design factors is essential to reduce carbon emissions.This paper proposes an ensemble learning algorithm combining Bayesian optimization and extreme gradient boosting(BO-XGBoost)to predict LCCO_(2) accurately in residential buildings.First,this study collected and calculated the LCCO_(2) of 121 residential buildings in Chengdu,China.Second,a carbon emission prediction model was developed using XGBoost based on 15 design factors,and hyperparameter optimization was performed using the BO algorithm.Finally,the model performance was evaluated using two evaluation metrics,coefficient of determination(R2)and root mean square error(RMSE),and the prediction performance of other models was compared with that of the BO-XGBoost model.The results show that the RMSE of the proposed BO-XGBoost for predicting LCCO_(2) in residential buildings is at least 40%lower compared to other models.The method adopted in this study can help designers accurately predict building LCCO_(2) at the early design stage and provide methodological support for similar studies in the future.

Carbon emissions from buildings based on a life cycle analysis:carbon reduction measures and effects of green building standards in China

Carbon emissions from buildings account for approximately half of China’s total social carbon emissions.Focusing only on the carbon emissions of building operation tends to neglect the carbon emissions of other related parts of the building sector,thus slowing down the progress of carbon peaking in the building sector.By applying life-cycle analysis to calculate carbon emissions throughout the building’s life cycle,the performance of carbon emissions at each stage of building materials,construction,operation and end-of-life demolition can be identified,so that carbon reduction strategies in building design can be selected..This paper constructed a method for calculating the carbon emissions of green buildings in whole-building life cycle,and conducted a summary analysis of the carbon emissions of 33 projects that were awarded green building certification.The study found that the Chinese Assessment Standard for Green Buildings has a significant effect on reducing the carbon emissions of buildings in whole-building life cycle.Compared with the current average operational carbon emissions of buildings in China,the carbon intensity of green public buildings is 41.43%lower under this standard and the carbon intensity of green residential buildings is 13.99%lower.A carbon correlation analysis of the provisions of the current Chinese Assessment Standard for Green Buildings was conducted,comparing the changes in the carbon intensity of buildings before and after the revision of the standards.The study concluded that the new version of the standards has a greater impact on public buildings than residential buildings,the requirement of carbon emission reduction in the production stage of building materials is strengthened in terms of carbon emission during the whole-building life cycle.This study addresses the current problem of unclear carbon emission reduction effect of green buildings.

Contribution of nearly-zero energy buildings standards enforcement to achieve carbon neutral in urban area by 2060

Nearly-zero energy buildings (NZEB) would effectively improve building energy efficiency and promote building electrification. By using a carbon emission model integrated into a bottom-up mid-to-long term energy consumption model, this study analyzes the contribution of NZEB standards to carbon emission targets in the urban area of China by 2060. Three scenarios are set, namely BAU, steady development (S1), and high-speed development (S2). For BAU, the total carbon emissions will reach a peak of 1.94 Gt CO_(2) by 2040. In S1 scenario, total building carbon emissions will reach the peak of 1.72 Gt CO_(2) by 2030. In S2 scenario, the carbon emissions will reach a peak by 2025 with 1.64 Gt CO_(2). Under S1 scenario, which features consistency with NZEB market development and periodic improvement of building energy-efficiency standards, the carbon emission peak in 2030 will be accomplished. To achieve carbon neutrality by 2060, the upgrading of building energy standards to NZEB will contribute 50.1%, while zero-carbon electricity contribution is 49.9%. It is concluded that 2025, 2030, and 2035 could be set as mandatory enforcement years for ultra-low energy buildings, NZEB and zero energy building (ZEB), respectively.

Technical pathways of dual carbon control in China’s buildings sector

Reducing carbon emissions in the buildings sector is of great significance to the realization of China’s carbon peak and neutrality goals.By analyzing factors influencing buildings carbon emissions at the operational stage,this paper applies the China Building Carbon Emission Model(CBCEM)to make medium and long-term forecasts of China’s building operation carbon emissions,discussing the goals and realization paths of China’s dual carbon goals in the buildings sector.The results show that building operation carbon emissions,according to the current development model in the buildings sector,will peak in 2038-2040 with a peak carbon emission of about 3.15 billion tons of CO_(2);however,by 2060,carbon emissions will still be 2.72 billion tons of CO_(2),falling short of China’s dual carbon goals.The carbon saving effects of three scenarios,namely clean grid priority,building photovoltaic priority and energy efficiency enhancement priority,were measured and shown to be significant in all three scenarios,but the building photovoltaic priority and energy efficiency enhancement priority scenarios were superior in comparison.