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.

In this study, the carbon emissions of Jilin University of Architecture and Technology were comprehensively calculated using the “Guidelines for accounting of carbon emissions of university campuses” issued by the China Association for Energy Conservation in Buildings. The total emissions for 2023 amounted to 13,571.85 tonnes of CO₂ equivalents, with a per person emission of 0.93 tonnes. Incorporating carbon offsets like green plant sequestration, renewable energy, and waste recycling reduced emissions by 9007.68 tonnes, resulting in a net emission of 4564.17 tonnes and a per person net emission of 0.31 tonnes. To further cut emissions, the university implemented strategies such as nearly zero-energy buildings, clean energy heating, energy monitoring, and green courses. Despite these efforts, achieving carbon neutrality remains challenging. The university could explore opportunities to increase renewable energy use or procure green electricity. Its adoption of clean electricity for heating in the severe cold zones not only supports carbon neutrality but also serves as a model for similar campuses.

Ground source heat pump (GSHP) systems, while energy-efficient, often face persistent soil thermal imbalance in heating-dominated severe cold regions, which undermines their long-term performance and sustainability. This study proposes a TRNSYS-GenOpt framework for the life-cycle cost optimization of hybrid GSHP systems integrating electric boilers and geothermal regulation towers. A transient model for a 5650 m² fire station in Changchun was developed, employing the Hooke–Jeeves algorithm to co-optimize boiler capacity, borehole depth, and geothermal regulation tower airflow under constraints on heating supply temperature and soil thermal balance. Time-of-use electricity pricing was incorporated for realistic operational economics. The optimized configuration (148 m, 864.8 kW, 290,400 m³/h) achieved a minimum 20-year life-cycle cost of CNY 1.13 million. Sensitivity analysis revealed “rigid design, flexible cost” characteristics: optimal parameters remained invariant across discount rate variations (3.5–7.5%) and equipment costs (±20%), while life-cycle cost showed the highest sensitivity to electricity pricing and discount rates. The long-term simulation confirmed compliance with all physical constraints. This methodology demonstrates that thermodynamic constraints supersede economic trade-offs in severe cold climates, providing engineers with a reliable tool for sustainable hybrid geothermal system design.