In light of the accelerated pace of economic growth and urbanisation, the transformation of green buildings has emerged as a prominent area of research.A considerable number of existing buildings have been constructed and are still in use.However, the energy consumption and environmental impact throughout the entire life cycle of these buildings are not adequately considered in the renovation design.This results in high energy consumption and poor indoor comfort.In this work, we include improving the thermal insulation of buildings, such as thickening the insulation of external walls and replacing energy-efficient windows to reduce energy losses caused by temperature differences between indoor and outdoor buildings; Adopt energy-efficient HVAC systems to reduce energy consumption and improve indoor air quality by upgrading equipment efficiency, optimizing duct design, and intelligent control systems; At the same time, we will introduce renewable energy sources such as solar energy, and we will not only install solar photovoltaic panels to generate electricity, but also use solar thermal collector systems to provide hot water and heating, so as to achieve diversified and sustainable use of energy.Combined, these measures can effectively reduce the overall energy consumption of the building, reduce carbon emissions, and improve the comfort and health of the indoor environment.During the experimental analysis, the energy consumption and indoor comfort before and after the renovation were evaluated, and the results showed that the energy consumption was significantly reduced and living comfort was improved.