From shallow geothermal energy systems to our buildings: The role of thermal conductivity for heat transfer and energy efficiency

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Space heating and cooling currently makes up the world's largest energy sector, accounting for approximately 50% of the final energy consumption.  This figure is expected to grow rapidly over the coming decades due to economic and population growth, and inevitable increase in urbanisation. At the same time, the world is experiencing one of the most severe global energy crises in history, impacting the fossil fuels’ availability and cost. Thus, more than ever, there is an urgent need for innovative technologies to harvest renewable energy resources, to decrease our dependence on fossil fuels.

Shallow geothermal energy is one of these resources which can be harvested by energy geostructures, geothermal boreholes or abandoned coal mines. The appropriate design and long-term efficiency of these technologies strongly depend on the thermal properties of the subsurface (i.e., thermal conductivity). Yet, in current practice, thermal conductivity is roughly estimated by soil type and is assumed to be constant throughout the lifetime of these systems, although it is highly influenced by several geological (soil type and structure) and environmental factors (water content and temperature).

In this PhD project, a thorough experimental programme will be undertaken to investigate the impact of the above factors on soils’ thermal conductivity, as well as on the long-term performance of shallow geothermal systems to ensure their efficiency. Initially, thermal conductivity tests will be performed on soil samples to investigate the impact of geological and environmental factors. This will be followed by model-scale tests on energy geostructures to fully access the variation of thermal conductivity during their operation (due to water migration and change in void ratio), as well as its influence on the long-term energy and structural performance. For this purpose, heat exchange operations will be imposed on model-scale pile foundations, and the moisture migration, variations of temperature, void ratio, thermal conductivity within the soil as well as temperature and axial stresses within the model-pile will be monitored. Finally, a numerical model, validated by the model-scale test results, will be exploited to run energy performance analysis emphasizing the role of thermal conductivity for the long-term efficiency of shallow geothermal energy systems.

The project’s outcomes will not only fill the knowledge gap regarding the importance of soil’s thermal conductivity for the design of shallow geothermal energy systems but will also provide fundamental information on how the thermal properties of geological formations at shallow depths will be influenced by climate change in the near future. 


This is a full scholarship which will cover tuition fees (Home and Oversees) and provide an annual stipend (currently £17,668) for 42 months. Thereafter, candidates will be expected to pay a continuing affiliation fee (currently £130) whilst they complete their thesis.


This scholarship is available to Home and Overseas students. The successful candidate will be based on campus in Edinburgh.

To be eligible, applicants should have a first-class honours degree in a relevant subject or a 2.1 honours degree plus Masters (or equivalent experience. Scholarships will be awarded by competitive merit, taking into account the academic ability of the applicant.

We recognise that not every talented researcher will have had the same opportunities to advance their careers. We therefore will account for any particular circumstances that applicants disclose (e.g. parental leave, caring duties, part-time jobs to support studies, disabilities etc.) to ensure an inclusive and fair recruitment process.   

How to apply

To apply you must complete our online application form.

Please select PhD Civil Engineering as the programme and include the full project title, reference number and supervisor name on your application form. You will also need to provide a CV, a supporting statement (1-5 A4 pages) outlining your suitability and how you would approach the project, a copy of your degree certificate(s) and relevant transcripts and an academic reference.

You must also provide proof of your ability in the English language (if English is not your mother tongue or if you have not already completed a degree that was taught in English within the last 2 years). We require an IELTS certificate showing an overall score of at least 6.5 with no component scoring less than 6.0 or a TOEFL certificate with a minimum score of 90 points.

Please address informal questions to Dr Melis Sutman

If you have any general queries about the applications process, please contact


The closing date for applications is 17th April 2023 and applicants must be available to start in September 2023.