Elevated Energy: Vertical Geothermal Loops

Vertical geothermal loops are an important part of ground-source heat pump systems. They provide a way to use the steady temperature below the Earth’s surface for heating and cooling buildings. Instead of relying on shallow trenches, vertical loops are drilled deep into the ground. This makes them especially useful where land is limited, or where heating and cooling loads are higher than a horizontal system can handle.

This blog explains what vertical geothermal loops are, how they work, their benefits, design considerations, and common challenges. It also covers how they compare with horizontal systems, examples of where they are used, and the role they can play in future energy systems.

What are vertical geothermal loops?

Vertical geothermal loops consist of a series of boreholes drilled into the ground. Typically, these boreholes range from 50 to 150 metres deep, although depths can vary depending on geology and energy demand.

Plastic pipes, usually made of high-density polyethylene (HDPE), are inserted into each borehole. These pipes form a closed loop filled with a water-based fluid, often mixed with antifreeze. The fluid circulates continuously, carrying heat between the ground and the heat pump.

The main difference between vertical and horizontal loops lies in layout. Horizontal systems use long trenches a few metres below the surface, while vertical systems go much deeper. This allows vertical loops to access stable ground temperatures year-round.

How vertical geothermal loops work

Drilling boreholes: Specialist equipment drills narrow shafts into the ground at predetermined depths.
Installing pipes: U-shaped pipes are lowered into each borehole and grouted in place. The grout ensures good thermal contact with the surrounding soil or rock.
Circulating fluid: The loop fluid absorbs heat from the ground in winter or releases heat into it during summer.
Heat pump operation: A heat pump transfers heat from the loop fluid to the building’s heating system, or reverses the process for cooling.

Because the temperature a few dozen metres below the surface is relatively constant, vertical geothermal loops work efficiently in all seasons.

Benefits of vertical geothermal loops

Efficient use of space
One of the most significant benefits is their compact footprint. Unlike horizontal loops, which need large land areas, vertical systems require only a series of boreholes. This makes them well-suited to schools, universities, hospitals, and urban buildings with limited space.

Stable performance
Deep ground temperatures remain steady throughout the year. This allows vertical loops to provide consistent efficiency regardless of weather or seasonal changes.

Longevity
With proper installation, vertical loops can last 50 years or more. The underground pipes are protected from external damage and environmental wear.

Reduced emissions
When powered by renewable electricity, vertical geothermal loops provide heating and cooling with minimal carbon output.

Scalability
Multiple boreholes can be drilled to match the size of the building or campus. Large systems may use dozens or even hundreds of boreholes linked together.

Design considerations

When planning a vertical geothermal loop system, several factors must be addressed:

Geological conditions: Soil type, rock structure, and groundwater levels influence drilling depth and performance.
Heat load: The building’s heating and cooling requirements determine how many boreholes are needed.
Spacing: Boreholes must be spaced far enough apart to avoid thermal interference between loops.
Grout quality: Proper grouting ensures efficient heat transfer and prevents contamination of groundwater.
System integration: The loop must be matched with the right heat pump size and distribution system, such as underfloor heating or fan coils.

Vertical vs horizontal loops

Land availability

Vertical loops require less surface area.
Horizontal loops need long trenches, often unsuitable for dense urban areas.

Installation cost

Vertical systems cost more to install due to drilling expenses.
Horizontal systems are cheaper but need large, open land.

Efficiency

Vertical loops benefit from stable temperatures at depth.
Horizontal loops can be affected by surface conditions such as frost or heatwaves.

Suitability

Vertical loops are ideal for cities, large institutions, or where long-term energy savings justify higher initial cost.
Horizontal loops work well for rural properties with available land.

Challenges of vertical geothermal loops

High upfront cost: Drilling boreholes requires specialist equipment and skilled labour, making installation expensive.
Permitting: In some regions, drilling deep boreholes requires complex permits.
Geological risk: Unexpected rock formations or groundwater issues can increase cost or reduce efficiency.
Long payback time: Although operating costs are low, it can take years to recover installation expenses.

Despite these challenges, the long lifespan and efficiency of vertical loops often make them worthwhile investments.

Examples of vertical geothermal loop use

Universities: Many campuses with limited space install vertical loops beneath courtyards or sports fields. This provides sustainable heating for lecture halls, libraries, and residences.
Hospitals: Reliable year-round heating and cooling is critical in healthcare facilities. Vertical loops meet these needs without relying on fossil fuels.
Commercial buildings: Office towers and shopping centres in cities often adopt vertical loops, taking advantage of small footprints and stable operation.
Residential complexes: High-rise apartments can use vertical loops as part of district heating and cooling systems.

Environmental impact

Vertical geothermal loops contribute to lower emissions, improved air quality, and reduced reliance on fossil fuels. Unlike gas boilers, they do not release combustion by-products such as nitrogen oxides or particulates. By cutting carbon emissions, vertical loop systems help buildings move closer to net-zero targets.

Future developments

Advances in drilling technology may reduce the cost of installing vertical geothermal loops. Better borehole mapping, automated drilling rigs, and improved grouting materials are already making systems more accessible.

Integration with smart controls and thermal storage can further improve efficiency. For example, surplus heat can be stored underground in summer and retrieved in winter. This seasonal storage concept could transform how vertical loops are used in urban environments.

Conclusion

Vertical geothermal loops provide an efficient way to harness steady underground temperatures for heating and cooling. They are compact, reliable, and long-lasting. While installation costs are higher than horizontal systems, the positives include consistent performance, reduced emissions, and suitability for urban areas where land is scarce.

As technology improves and the need for low-carbon energy grows, vertical geothermal loops are likely to play a larger role in sustainable building strategies. Their flexibility makes them suitable for universities, hospitals, offices, and residential complexes alike.

By adopting vertical geothermal loops, organisations can secure reliable energy supplies, reduce emissions, and invest in infrastructure that will last for decades.

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