Numerous Chinese rural buildings in severe cold climate face considerable difficulties in reducing high heating expenses and CO2 emissions, primarily due to poor thermal performance of building envelope and the reliance on inefficient coal-based decentralized heating systems. Although energy-efficient envelope renovations and electrification of building energy systems are promoted, they are frequently treated separately rather than being integrated into one analysis. This study addresses these issues by applying a multi-objective optimization framework that simultaneously improves the building envelope and transitions to an electric boiler, with the additional consideration of a rooftop photovoltaic system. The objectives are to minimize life cycle costs and CO2 emissions. A typical single-family rural house was selected as the case study. IDA ICE was applied to develop the building energy model. This study compares the effectiveness of individual envelope and energy system renovations against an integrated renovation approach. The results indicate that integrated renovation solution further reduces CO2 emissions compared to separate renovations. Incorporating a photovoltaic system further enhances performance, reducing CO2 emissions to 27–33 kg CO2/m2 and lowering LCC by 38% compared to pre-renovation level. Besides, selling excess photovoltaic-generated electricity back to the grid results in over 65 CNY/m2 in revenue, making the renovation plan more cost effective and environmentally sustainable.