Water-source and ground-source heat pump systems are energy-efficient air-conditioning systems that utilize shallow geothermal resources underground (also known as geothermal energy, including groundwater, soil, or surface water) for both heating and cooling.

Water-source and ground-source heat pump systems harness shallow geothermal resources underground (such as groundwater, soil, or surface water) to provide both heating and cooling in an energy-efficient manner. By inputting a small amount of electrical energy, the system transfers thermal energy from a low temperature level to a high temperature level. In winter, geothermal energy serves as the heat source for heating; in summer, it acts as the cooling source for air-conditioning. The unit consumes 1kW of energy to produce over 4~5kW of cooling/heating capacity. Drawing energy from underground sources, the system emits no waste gases, wastewater, or waste residue to the environment, making it an ideal "green air-conditioning" solution. It can be widely applied in office buildings, hotels, schools, dormitories, hospitals, restaurants, shopping malls, villas, residential buildings, and other fields.

Water-source and ground-source heat pump technology is currently one of the most energy-efficient cooling and heating methods in air-conditioning systems, making it a popular choice. The Chinese government strongly advocates for its use, and according to policy regulations, buildings that adopt this technology can receive government policy support by applying to the local government, with reductions or exemptions of building ancillary fees ranging from 140 to 200 yuan per square meter.

Based on the different media for energy extraction, water-source and ground-source heat pump systems can be classified into three types:

1. Groundwater system (open-loop "well water" system):
   This system absorbs or releases heat from groundwater to achieve heating or cooling in buildings. The biggest advantage of this solution is that groundwater temperature remains constant, typically between 10~16℃, which can reduce both initial investment and operating costs. Open-loop systems are usually applied in coastal areas where soil conditions allow water to be reinjected into the soil's aquifer through recharge wells.

2. Soil buried pipe system (closed-loop geothermal system):
   Heat exchangers (pipes) are laid in the soil to directly exchange heat with the soil. In winter, they supply heat to the unit; in summer, they absorb heat discharged by the unit. Vertical loops are installed by drilling vertical holes in the soil and installing polyethylene pipes in them. Horizontal loops involve laying heat exchangers (pipes) 1.5m below the ground surface. Both vertical and horizontal loops extract or release heat from the soil.

3. Surface water system (surface water or lake water circulation system):
   This system utilizes surface water resources such as rivers, lakes, seas, etc., by installing heat exchange devices in the water for heat exchange. Closed-loop heat exchange devices are installed in lakes or other water bodies near the building to provide or release heat for the building. The heat exchange devices must be aesthetically pleasing and easily drained. The size and depth of the lake are particularly critical, requiring precise calculations to ensure that the lake water can meet the building's cooling and heating needs.