AbstractThe green loans program has continued to attract attention as an effective measure for promoting green retrofit to reduce energy consumption in old buildings. Various external factors negatively affect the decision-making process for the government and building owners. In particular, it is unclear how incentives and penalties take effect and to what extent they can influence the green loans program. Therefore, this study identified the influence of political factors, such as loan support and carbon taxation, on the strategic choices of the government and building owners. The results of this study showed that (1) as the supporting interest rate increases, both government and building owners are more likely to select a positive strategy; (2) as the carbon tax rate increases, both government and building owners are more likely to select a positive strategy; and (3) if the maximum supporting interest rate of 4.45% is applied, the greenhouse gas (GHG) emission reduction effect can be increased by about 3–5 times from the current level. It is not easy to achieve the national carbon emission reduction target for 2030 and 2050 only through green retrofitting of old buildings under the green loans program. Therefore, the government should develop an additional research and development budget and encourage developers to enhance the efficiency of green technologies.