Since the 1980s and 1990s, the construction of curtain walls has been agilely applied in the urban construction of Shanghai. The urban construction of Shanghai has also gone through a stage of rapid development, with many high-rise buildings and dense construction in the middle urban area, and the flow of people is also very dense. According to statistics, by the end of 2010, there were over 4000 existing curtain wall constructions in Shanghai, with a total construction area of approximately 10 million square meters, and over 1500 constructions that had been in use for more than 10 years.

　　The professional standards for glass curtain walls were first introduced in 1996 and were revised in 2003; The professional standards for stone and metal curtain walls were introduced in 2001. In the early stages of career development, skill standards were lagging behind, and many existing curtain walls were built before 1996, resulting in inherent deficiencies. The research results show that the construction of curtain wall projects before the introduction of professional standards had many risks due to the lack of skill basis for description, manufacturing, installation, testing, and inspection.

　　On the other hand, the construction of curtain walls as an external enclosure layout has relatively low stiffness and a lifespan shorter than the service life of the building, resulting in "functional degradation". The quality guarantee period for silicone layout adhesive used in hidden frame glass curtain walls is ten years, and research has shown that its function will degrade over time; Mechanical or chemical anchor bolts may also experience anchor loosening under long-term repeated loading; Corrosion appearance of metal connectors; Loose connecting bolts; Stone hollowing or loose fixation, etc.

　　On February 1, 2012, the Shanghai Municipal People's Government revised Government Order No. 78 "Rules for the Use of Safety Glass in Shanghai Buildings", emphasizing the necessity of using safety glass in various types of ceilings, visiting elevators, indoor partitions, skewed installation windows, railings in staircases, balconies, corridors, and courtyards, visiting windows and holes in aquariums and swimming pools, entrances and exits of public buildings, and related areas that are prone to impact and human injury.

　　According to the resolution on strengthening energy-saving operations, it is necessary to vigorously carry out energy-saving and land saving construction, promote the strict implementation of the 50% energy-saving standard for new residential and public buildings, and prioritize the implementation of the 65% energy-saving standard in municipalities directly under the central government and areas with conditions. Glass curtain walls, as the physical interface that can directly interact between the exterior and interior of buildings, are one of the most important factors affecting indoor thermal environment quality and construction energy consumption. According to statistics, the layout of curtain walls, doors, windows, and other enclosures accounts for approximately 72% of the total energy consumption during construction. Therefore, when commenting on the impact and role of building a comprehensive energy-saving system, the energy-saving of curtain walls, doors, and windows cannot be ignored or avoided.

　　1. There is a great need for safety and energy-saving testing of existing curtain walls

　　The two questions about the safety and energy efficiency of existing curtain wall construction have received attention from the relevant departments of the Shanghai Municipal Government and many property owners. The Shanghai Municipal Commission of Construction and Management and the Shanghai Municipal Housing and Land Bureau jointly organized a comprehensive rectification operation of the existing curtain walls in the city. Based on all the research, they successively organized seminars on the safety function testing and evaluation skills of the existing glass curtain walls, as well as the energy-saving testing and evaluation skills of the existing curtain walls; Established a database of existing building curtain wall information in Shanghai, which includes primary information on local curtain wall construction projects, facilitating macro level management of related parts; The local regulations for the evaluation and testing skills of glass curtain wall safety functions have been drafted and published for the first time nationwide.

　　2. Following a series of government energy-saving regulations, a number of public buildings such as hotels and sports venues have been using curtain walls for over ten years. Existing curtain wall energy-saving testing and evaluation have been launched, and the Shanghai Tourism Bureau has proposed a comprehensive plan for energy-saving testing of hotels. As the Jianguo Hotel has completed all the testing, evaluation, and renovation of its exterior layout, not only has the function of building the facade been fully promoted, but the energy-saving effect is also significant.

　　3. Testing and evaluation skills for existing curtain wall construction

Regarding the primary questions about the existing construction of glass curtain walls (including glass questions, aluminum alloy component strength questions, layout adhesive quality questions, hardware quality questions, etc.), analyze the primary factors affecting safety, and establish safety function testing and evaluation methods for existing construction of glass curtain walls from the identification of glass varieties and types, physical function and aging status analysis of silicone layout sealants, primary stress layout of curtain walls, and functional testing of connecting components.

　　The inspection and evaluation of existing glass curtain walls can be summarized and evaluated based on their load-bearing capacity, layout and layout, and deformation of components and nodes to determine the overall safety function level.

　　The identification of safety function level is usually based on the carrying capacity, but the difference between layout, deformation, etc. and the carrying capacity level should not exceed level 1; When any sub item has a Du level, the method should be adopted immediately, so the safety function level of this curtain wall project is Du level.

　　When the safety function level of glass curtain walls is set to Bu level, Cu level, or Du level, disposal methods should be selectively proposed based on the severity of the shortcomings and specific conditions.

　　The layout repair and reinforcement methods for Bu level, Cu level, or Du level largely depend on the appraisal conclusion. Generally speaking, for layouts that are easy to repair and reinforce, the consensus tends to favor preservation and adoption of appropriate repair and reinforcement methods; As for layouts that are difficult to modify or components that are easy to replace, the consensus usually tends to be reconstruction or replacement.

　　4. Energy saving testing skills for existing curtain wall construction

　　The thermal factors that affect the layout of exterior enclosures such as curtain walls, doors, and windows are primarily convection, conduction, and radiation. Therefore, the evaluation of the thermal functions of curtain walls should also revolve around these three aspects.

　　4.1 On site inspection of curtain wall airtightness

　　The principle of on-site airtightness testing is completely the same as that of laboratory testing. Currently, there are professional testing equipment for on-site airtightness of doors and windows in China. There are detection equipment for a certain room or door/window of a building in foreign literature.

　　4.2 Detection of visible light transmittance, reflectance, and shading coefficient of 4,2 glass

　　The visible light transmittance, reflectance, and shading coefficient of glass can be tested by selecting different types of glass samples for laboratory testing and analysis. The data obtained from the testing and analysis can be used for thermal simulation and accounting.

　　4.3 Thermal simulation accounting

　　The thermal simulation calculation of curtain walls can be carried out using Lawrence Berkeley Laboratory software OPTICS, THERM, WINDOW for thermal analysis of nodes and panels. The calculation unit panels are usually selected from typical panels, and the symmetry axis is treated with marginal insulation.

　　5. Conclusions

　　In addition to skill factors, there are also other economic factors that affect the construction and inspection of curtain walls, such as disorderly property rights connections and insufficient repair funds to cover renovation costs. It is necessary to ensure that the building remains in normal use. Therefore, in addition to the primary responsibility of the property owner, the relevant government departments should establish corresponding incentive mechanisms in terms of urban public safety and energy conservation to promote the implementation of this project.