Under China national city resilience policies, the country has been pushing the optimization of urban spatial structure and promoting the building quality by utilizing frontier digital and creative technologies to contribute to the realization of the carbon peak & carbon neutral targets. Although with the existing limitation, this retrofit project is aimed to upgrade building function and improve indoor thermal comfort within the semi-open concourse areas by maximum reuse of original materials and the visualized energy saving solutions. With the application of computational fluid dynamics (CFD) simulation analysis and market maturing new technologies and products, meanwhile referring to international similar practice, it is one of our hope that the proposed design in this project can provide a better indoor quality with low energy/cost effective HVAC system solutions to large scale semi-open commercial building areas, as well as giving the reference to the related theory study, data support and actual building case study for the future projects. The carbon peak and carbon neutrality of China government policy has been considered into energy saving retrofit projects and refers to the requirement of Union National sustainable development 2030 plan. The retrofit project focused on central chiller energy saving model and high performance chilled-water plant room design. The other application also designed such as cooling tower computational fluid dynamic technology application, energy balance valve setting, indoor air quality and heating water supply equipment coupling with renewable energy sources management. Provided the specified upgrade design and creative spotlight. According to the series implementation, obtained the chiller water system energy consumption from ex-19 million kW-h per year, deducted to 7 million kW-h per year now. Totally saved energy over 12 million kW-h per year and 63% decrease with excellent performance in energy saving.