Energy efficient building projects has become the focus of sustainable development. In this article, 2 indexes, energy-saving sensitivity and energy-saving contribution, are proposed to assess the energy efficiency of residential buildings. Four green measures to improve the energy efficiency of residential building with either passive or active technologies are designed and their saving performances are evaluated with the case study of a residential building simulation model in Changchun, region in China using the 2 indexes by simulations in the Designbuilder simulation software. The results reveal that improving the energy efficiency of residential buildings in severely cold regions should be focused on two key energy consumption factors, A1-heating (gas) and A2-zone sensible heating. Green measures M4-modifying the heating ventilating and air conditioning system and M1-improving envelope structures are found with high energy-saving sensitivities on the energy consumption factors A1 and A2. The energy-saving contribution of green measures M4 is the largest with the value of 80.17%, and that of green measure M2-adding shading facilities is the smallest with the negative value of − 8.53%. These results suggest that M4 and M1 are the effective green energy-saving renovation measures of the residential buildings in severely cold regions. The assessment method and simulation case study results provide a theoretical foundation and practical suggestions for the decision making to effectively reduce the energy consumption of residential buildings in severely cold regions by adopting appropriate green measures.