Which heating and cooling system uses the earth as both a heating and cooling medium?

Which heating and cooling system uses the earth as both a heating and cooling medium?

• A. Solar heating system
• B. District cooling system
• C. Air-source heat pump
• D. Geothermal system

Answer: (D)

Underground temperatures stay relatively constant year-round, which geothermal systems take advantage of to move heat efficiently. A loop buried in the ground carries a fluid that exchanges heat with the earth. In winter, heat flows from the earth into the fluid and is transferred by a heat pump into the building, providing warming. In summer, the process reverses: heat is drawn from the building and released into the earth, giving cooling. Because the earth acts as a heat source in heating and a heat sink in cooling, this approach uses the ground for both heating and cooling. Other options rely on solar energy, a centralized plant for cooling, or outdoor air for heat exchange, rather than the ground, so they don’t use the earth as the dual-purpose medium in the same way.

Underground temperatures stay relatively constant year-round, which geothermal systems take advantage of to move heat efficiently. A loop buried in the ground carries a fluid that exchanges heat with the earth. In winter, heat flows from the earth into the fluid and is transferred by a heat pump into the building, providing warming. In summer, the process reverses: heat is drawn from the building and released into the earth, giving cooling. Because the earth acts as a heat source in heating and a heat sink in cooling, this approach uses the ground for both heating and cooling. Other options rely on solar energy, a centralized plant for cooling, or outdoor air for heat exchange, rather than the ground, so they don’t use the earth as the dual-purpose medium in the same way.