The importance of international climate change countermeasures and environmental issues has grown significantly in the 21st century. With the emergence of greenhouse gas emissions trading and clean development mechanisms, new rules are shaping the energy market, prompting nations to develop response strategies. Under the Paris Agreement, reducing greenhouse gas emissions from the building sector is essential for achieving carbon neutrality by 2050. In Korea, approximately one-quarter of total energy consumption is attributed to residential and commercial/public buildings, making energy savings in this sector urgent. Heating and cooling account for the largest share of building energy consumption: thermal energy constitutes about 28 percent of total national energy use, while electricity represents 13 percent. Most thermal energy is consumed in homes and buildings—approximately 90 percent residential, 8 percent commercial, and 2 percent public—meaning that improving efficiency in this area can significantly reduce national energy use and lower CO₂ emissions. Heat pumps, which provide high-efficiency heating and cooling, are recognized as a viable replacement for traditional heat sources and are increasingly viewed as a crucial measure in the fight against climate change. Buildings contribute to roughly 25 percent of domestic greenhouse gas emissions (including indirect emissions), with household heating consuming 65 percent of heating energy. Many experts agree that transitioning from fossil fuel heating to heat pumps, including air-source pumps, is essential. However, while many countries classify air heat as renewable energy, there is still debate in Korea regarding its inclusion in renewable energy legislation, highlighting the need for institutional improvements to promote the adoption of air-source heat pumps. This study predicts the CO₂ reduction effect of converting existing heating systems in domestic single-family houses to heat pumps and estimates the reduction potential through 2035.