In short: a closed loop carries fluid deep into the bedrock and back. The rock warms it, and heat pumps in the heating centre raise that heat to the temperature the building uses. No groundwater is extracted. We design the system, drill the borehole with our own GM2000 rig, then install and commission the heating centre and building connection.
Warmth that rises with depth
Heat flows constantly from the Earth's interior towards the surface. Near the surface, ground temperatures follow the seasons. Further down, the bedrock is steady through winter and summer, and its temperature generally rises with depth.
How quickly it rises depends on the local geology, so depth is an engineering decision rather than a fixed number. Our current planning range for rock temperature at about 2,000 metres is 30 to 40 °C. The actual temperature is site-specific, and we assess it for every property. SGU: temperature measurements in deep boreholes.
A closed loop, sealed from the rock
The borehole houses a closed-loop collector. A heat-transfer fluid travels down the collector and back up again. On the way, heat moves from the warmer rock through the collector wall into the fluid, which carries it to the heating centre at the surface.
The loop is sealed. The same fluid circulates again and again, and nothing is pumped out of the rock: no groundwater is extracted, and none is brought into the building. SGU: ground-source heating.
We drill the borehole with our own GM2000 rig. We plan the worksite around the property, with compressors, rod handling and cuttings containment, and record the drilling data for follow-up and handover. See the GM2000.
Heat pumps lift the heat to building temperature
The fluid returns from the rock warmer than it went down, but usually not warm enough to heat the building directly. The heating centre closes that gap.
Inside it, the ground-loop fluid and the heat pump's refrigerant circulate in separate circuits. A heat exchanger passes energy from the ground loop to the refrigerant. An electrically driven compressor raises the refrigerant's pressure and temperature, and a second heat exchanger passes useful heat to the building's heating circuit.
Heat pumps need electricity, and circulation pumps and controls use power too. The heat delivered combines energy collected from the rock with the electricity supplied, which is why a well-designed system delivers more heat than the electricity it consumes. IEA: how a heat pump works.
One principle shapes the whole design: the smaller the lift from source temperature to building temperature, the less electricity each unit of heat needs. A warm, steady source and sensible supply temperatures in the building work together.
One heating centre, designed for the building
The heating centre turns energy from the rock into useful heat for the building. We design it around that building: a cascade of heat-pump compressors, circulation pumps, storage and filtration, with controls and metering that make delivered heat and electricity use visible.
Annual heat demand tells us how much energy the property needs over a year. Peak demand sets the capacity needed in the coldest periods. Building temperatures, the available electrical supply and any provision for peak or backup heat complete the picture. Together, they decide how the borehole and heat pumps are sized.
What we do at each step
- Screen the property. You share the address, current heat source and rough heat demand. We check the technical fit and ask for anything missing.
- Design the complete system. Demand, peak load, geology, access and power shape the borehole, the heat-pump plant and the building connection.
- Drill the source. Our GM2000 rig drills the borehole that houses the closed-loop collector.
- Build and commission. We install the heating centre and building connection, then check temperatures, flows and controls before handover.
- Operate. The property team receives a documented starting point for operation and maintenance. You own the system, or buy metered heat while Geocadia owns and operates it.
In operation at Jordbro
At Catena's Jordbro property, Geocadia drilled a borehole about 2,000 metres deep with its own GM2000 rig. The borehole connects to a complete heating system. Installed and operating, the system was designed to supply about 1,500 MWh of heat a year.
The design uses four 60 kW heat pumps in a plant room of 25 to 40 m². It shows the scale of one system; every new property receives its own design. Explore the Jordbro project.
Start with the building
Bring the property address, heat-use history, current heating arrangement and intended timing. Where available, include peak-load information and operating temperatures.
We then assess how the ground conditions, a custom-designed heating centre and the building's needs fit together. That assessment is the basis for a property-specific system and commercial offer.
Sources and scope
- SGU: ground-source heating. Collector circulation and ground heat transfer. Domestic depths and output figures are not applied to a deep installation.
- SGU: temperature measurements in deep boreholes. Temperature variation with depth and geology. A site-specific assessment is still required.
- IEA: how a heat pump works. The refrigerant cycle, electrical input and transfer of useful heat.
These sources explain the underlying technology. Geocadia's system scope and commercial routes are assessed property by property; no general source establishes a site's performance or price.
Start with your property.
Share the address, current heating arrangement and rough heat demand to identify the next assessment.
Screen a property →