Thermogeological assessments for closed loop ground source heat pumps

A thermogeological assessment is the ground-source equivalent of a hydrogeological assessment. Before a closed loop borehole array is designed or drilled, it tells you what rock you'll drill through, how well that rock conducts heat, what could go wrong during drilling, and which permits apply. It is the most cost-effective way to get the design right first time.

What the assessment covers

- Geology from the surface to 200 m and beyond, with a predicted borehole log
- Thermal conductivity of each formation, drawn from our own database of measured rock thermal conductivities
- Undisturbed ground temperature for the site
- Drilling risks and hazards, such as unstable ground, artesian water, mine workings, contamination and buried services
- Outline borehole depth and spacing, based on the geology and site constraints
- Regulatory position, including whether the scheme meets the closed loop binding conditions in England or needs an environmental permit

Why it matters

Thermal conductivity drives the size of a closed loop array. A small error in the assumed value can add or remove many metres of drilling. Our assessment gives designers a realistic, site-specific starting value instead of a generic one. It also flags geological or regulatory problems before they become expensive surprises on site.

When to follow up with a thermal response test

On larger schemes, or where the geology is uncertain, we recommend confirming the assessment with a test borehole and a thermal response test. Measured values often allow the array to be optimised, reducing the total length of borehole needed.

How it fits into a project

Thermogeological assessment (desk study)
Initial array sizing and budget
Test borehole and thermal response test, on larger projects
Detailed design and modelling. See Closed Loop Systems.
Drilling, with installation support and testing

To see an example report or request a quote, email lawrence@aquifer.energy.