This work aimed to quantitatively study the carbon emissions and carbon reduction potential of a nearly Zero Energy Building in a severe cold zone of China from the perspective of its life cycle. The methods were based on China’s “Standard for building carbon emission calculation” (GB/T51366-2019), which include the production, transportation, operation, and demolition stages. For the nearly Zero Energy Building, the total carbon emissions over its whole life were 789.43 kg CO2/m2, an 86.20% reduction compared to the 5719.68 kg CO2/m2 for a 65% energy-saving building. The carbon emission percentages of the production stage and operation stage for the building materials are 75.62% and 20.40%, respectively. To enhance the carbon reduction potential, a sensitivity analysis was conducted to explore the impact of the use of a wood structural system, recycled concrete replacement, and photovoltaic power generation. The use of a wood structure system can achieve zero or negative carbon emissions in the production stage. The sensitivity of the carbon emissions of the nearly zero energy building (nZEB) to the increment of photovoltaic power generation is much higher than that of the recycled concrete replacement rate, providing a basis for further exploration of the development of nZEBs into zero carbon buildings.

The development of low-energy buildings is an important initiative to achieve carbon peaking by 2030 and carbon neutrality by 2060. According to the data of the relevant papers, if all the northern urban and rural buildings in China adopt passive ultra low energy building technology, it can save about 350 million tons of coal for heating and reduce about 900 million tons of carbon dioxide emissions each year. It’s of great significance to achieve the goals of “peak carbon dioxide emissions” and “carbon neutrality”. Starting from four key technologies for low-energy buildings, explanation and analysis the energy-saving methods for low-energy buildings, It also presents the challenges and suggestions for the development of low-energy buildings in China.

In the context of green development and sustainable development, in response to the national policy of “carbon neutrality and peak carbon dioxide emissions”, we will fully implement clean energy heating and reduce air pollution. Air energy is the representative, bringing the comfortable, efficient, safe and energy-saving environment to people. For an office building in Nanjing, which is located in hot-summer and cold-winter zone, an air source heat pump unit is designed as a cold and heat source system to meet the demand for heating in winter and cooling in summer. At the same time, compared with the traditional cold and heat source system which is designed central heating in winter and multi-line refrigeration in summer, the result of economic analysis shows that the use of air source heat pump as the cold and heat source system of office buildings is more economical and energy-saving. It is suitable to popularize and apply in China’s hot-summer and cold-winter zone.

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