The project belongs to the discipline of civil and architectural engineering planning and design, updating and renovation technology and application fields. Key technologies for improving the performance of existing buildings are proposed for the whole process of pre-renovation inspection and surveying, renovation design methods, construction, and green operation and maintenance. The main innovation points are as follows: 1. Establish a complete set of key technologies for three-dimensional laser scanning for rapid inspection of existing buildings before renovation: Develop three-dimensional laser scanning technology is used for pre-renovation detection methods of deformed complex buildings and large-span structures; innovatively propose an auxiliary technology for existing building renovation that combines three-dimensional laser scanning and drone tilt photography; Breakthroughs use three-dimensional laser scanning technology to assist in the three-dimensional collaborative design method of building structural bodies and surrounding complex environment and terrain to form design guidelines. 2. Innovatively propose a low-impact renovation and renewal design method for existing public buildings based on building energy conservation and environmental improvement: propose an umbrella-shaped ventilation tower and side courtyard that integrate structural renovation, space construction, lighting and ventilation under the constraints of existing building conditions. Structural and spatial design methods such as integration of green enclosure structures; Directly link various renovation design measures of office buildings with building energy consumption, build a building energy consumption simulation optimization auxiliary design tool, form design guidelines and obtain software copyright. 3. For the first time, a technical catalog for energy-saving renovation of existing residential buildings was systematically proposed: from six major parts: renovation of envelope structures, renovation of lighting systems, renovation of cold and hot source equipment, renovation of power equipment, and utilization of renewable energy, the technical catalog for energy-saving renovation of existing residential buildings and its release and implementation in the form of government documents are of great significance to promoting the energy-saving renovation of existing residential buildings in Shanghai. 4. For the first time, a series of key technologies to improve livable performance, such as installing elevators, are proposed for existing residential buildings: developing unpowered elevator shaft self-exhaust technology devices to reduce building energy consumption; proposing building block prefabricated assembly technology for elevator shaft structures; innovatively proposing a A waiting hall layout plan solves fire hazards, line of sight interference and energy consumption problems after installing a waiting hall. 5. Innovatively propose complete sets of construction technologies such as functional improvement and sustainable utilization technologies of historical buildings: build a continuous and upgraded roof repair and transformation technology, which realizes the green and energy-saving upgrading of buildings while protecting the architectural style; in response to the reuse of historical buildings such as garden residences, research and formation of spatial pattern optimization technology, modern functional equipment implantation technology, FM technology and external environment renovation technology have been developed to improve the comfort and energy conservation of buildings. 6. Innovatively establish low-impact construction technology during the renovation of public buildings with dense crowds of people: In order to ensure uninterrupted operation of public buildings with dense crowds of people while improving their functions, low-impact renovation construction technology has been proposed to form isolation and protection that is compatible with the building operation environment. Technology has developed equipment that integrates protection, operation platform, and channels, ensuring public safety at the interface and reducing the impact of construction operations on operating comfort. The adoption of green renovation construction technology reduces pollution emissions and improves the level of green renovation construction. 7. Systematically put forward the green operation and maintenance technical system and implementation suggestions for existing public buildings: Establish a green operation and maintenance technical system for existing public buildings covering green operation, maintenance and debugging technologies, and put forward implementation suggestions from three aspects: management mechanism, property management, and design feedback, forming the "Green Operation and Maintenance Related Technology List of Existing Public Buildings" and "One Guide to Improving Energy Efficiency in Public Buildings" provide operating guidelines and toolbooks for public building property managers, which is conducive to improving the green operation management level of existing public buildings in the city. Obtained 9 patents, software copyrights and intellectual property rights, and 1 item for the transformation of high-tech achievements; compiled 7 specifications and standards, published 12 papers, published 1 monograph, and formed 3 guidelines. The research results have been successfully applied in more than 80 engineering projects.