In recent years, the global energy environment has become increasingly severe, and the problems such as global warming, soaring carbon emissions, and excessive use of petrochemical energy have attracted increasing attention from all walks of life. The construction industry, which accounts for about 30% of the total energy consumption, needs to effectively manage and use renewable energy. The application of building information model (BIM) in the evaluation of retrofitting schemes of existing buildings is one of the main research issues in the field of building digital twins at present. The method of this research is to use 3D laser scanning technology to efficiently create the building energy model (BEM) of existing buildings and to identify and evaluate the feasibility of existing building retrofitting schemes. The purpose of this research is to evaluate the retrofitting scheme of existing buildings based on the concept of nearly zero‐energy buildings (nZEBs), aiming to improve the energy efficiency of existing buildings and use clean energy to satisfy building energy demand. According to the case study in this paper, an nZEBs solution suitable for the building can reduce building energy costs by 14.1%, increase solar photovoltaic power generation by 24.13%, and reduce carbon dioxide emissions by 4306.0 kg CO₂eq/a.

Poor indoor air quality reduces the comfort experienced in the environment and can also harm our physical health. Mechanical ventilation design plays an important role in improving the indoor environment and the safety of public toilets. Therefore, in this study, we aimed to evaluate public toilet ventilation design schemes through a digital twin to determine the most effective scheme for reducing indoor pollutant concentrations. In this study, we used Autodesk Revit to create a digital twin BIM of different ventilation systems. We simulated the diffusion of pollutants in these models using computational fluid dynamics (CFD)-based methods, and we used DesignBuilder to simulate building energy consumption. From the perspective of architectural design, we determined measures important for reducing the concentration of air pollutants by increasing the number and volume of air exchanges and controlling the installation height of exhaust vents. The results show that the ventilation design of an all-air air conditioning system with an exhaust height of 400 mm can remarkably improve the indoor environmental health and ventilation efficiency of public toilets, while consuming 20.4% less energy and reducing carbon emissions by 30,681 kg CO₂.

The outdoor wind environment and thermal environment are important factors affecting human comfort in cold winter conditions. The spatial layout of plant communities plays an important role in improving the outdoor microclimate and improving outdoor comfort. In order to explore the positive effect of plant layout on outdoor comfort in cold winter, this study took Xuzhou Tangfang Middle School with typical layout characteristics as the research object. In this study, we simulated the wind environment of these models using computational fluid dynamics (CFD) methods and the outdoor thermal environment using Ecotect (2011), and used linear regression and one-way ANOVA for mathematical statistics. The wind environment and Universal Thermal Climate Index (UTCI) of campus outdoor activities distributed in different spaces were analyzed and evaluated. The research results showed that the superposition of wind and thermal environments identified the key areas of the campus (cross-flow area and corner flow area) and showed a negative correlation. The staggered layout of the three plant combinations increases the wind prevention efficiency by 39.4%. At the same time, this study established the linkage mechanism of campus plant layout, environmental microclimate, and activity area comfort, which effectively improved outdoor human comfort in cold winter. This research can provide a reference for the remediation and improvement of the comfort of the same type of campus, and also provide data support and reference significance for the research on the outdoor pedestrian environment in winter.

The construction industry is energy-intensive and labor-intensive, which has great potential in reducing energy demand and carbon emissions. The construction method of off-site prefabricated components has many advantages to make it a good substitute for traditional methods. The purpose of this paper is to reduce the carbon emissions of prefabricated residential concrete members by improving the standardization rate of prefabricated components in the architectural design stage. In addition, this paper also uses building information modeling technology to establish Revit models and develops Revit using C# language to achieve rapid calculation of the prefabrication rate of building and standardization rate of components. The calculation results of the case show that, in the design stage, the carbon emissions are reduced by 2034.16kg CO₂e by improving the standardization rate of prefabricated components, accounting for 0.1552 of the carbon emissions of all prefabricated components. This study can help the designer reduce the carbon emissions of prefabricated components, and this technology may make a significant contribution in improving the environmental sustainability of prefabricated buildings.