How does the layout of a geothermal vertical loop differ from a horizontal loop?

Choosing the correct answer highlights the significant differences in design and installation between geothermal vertical loops and horizontal loops. Vertical loops are installed deep into the ground, utilizing drilled wells that reach depths typically ranging from 100 to 400 feet, depending on the site and climate conditions. This vertical configuration allows for a smaller footprint on the ground surface, making it particularly advantageous in areas with limited space.

In contrast, horizontal loops require a larger area because they are installed in trenches that must extend horizontally, typically several feet below the surface. This necessitates a greater surface area for installation, which can limit their applicability in densely populated or constrained locations.

The unique design of vertical loops allows them to access stable ground temperatures more effectively and can often enhance the energy efficiency of the system, but that's not the basis of the correct answer. Focusing specifically on the surface area aspect, vertical loops indeed require less ground surface area compared to their horizontal counterparts, making choice C the most accurate in this context.