The presentation focused on the achievements of NEXCEL project, including comprehensive enhancement of thermal and combustion performance of PU insulation materials, development of FRP insulation connectors for Ultra-Thick insulation layers, and optimization of prefabricated sandwich insulation wall structure for ultra-low energy consumption buildings.

Currently, the total energy consumption and carbon emissions in the entire process of construction in China account for 50%. The development of ultra-low energy buildings is an important way for China to achieve the "dual carbon" goals. Research has shown that improving the thermal insulation performance of the external wall is crucial for reducing energy consumption in ultra-low energy buildings. There are some issues with fire protection and durability for the traditional external wall insulation systems.

At present, the thickness of the insulation wall needs to reach 230mm, which increases the performance requirements for insulation connection components. It also affects the production, transportation, and architectural layout of prefabricated walls, thereby limiting the application of polyurethane insulation materials in the construction market in our country.

To address this, the project team has developed new polyether/ester raw materials, utilizing low boiling point and low thermal conductivity foaming agents. This reduces the radiative heat transfer during the foaming process without affecting the expansion ratio. In terms of flame retardancy, polyester/ether blends with rigid structures and phosphorus and chlorine elements are selected to enhance flame retardant performance and reduce the likelihood of material smoldering.