Trevor Butler

Investigating the potential of earth tube systems to provide an energy efficient method of cooling buildings.

Supervisors: Dr John Littlewoood – Director of Studies; Dr Huw Millward
Research Group / Theme: Ecological Built Environment Research & Enterprise Group (EBERE)
Research Degree Type: MPhil/PhD

Buildings are responsible for around 50% of global carbon dioxide (CO2) emissions. Through improved understanding of design, construction and operation of buildings, their environmental impact could reduce significantly.

The candidate has critically reviewed the state of the art in published knowledge of earth tube systems in different applications and found that there are conflicting views on their effectiveness and doubts on their suitability. However, based on his experience working as an Engineer in the extreme climate of Western Canada (exterior temperatures can range from -20°C in the winter to +40°C in the summer in the same location), he has found that this difference between outdoor air temperature and ground temperature may have the potential to meet the cooling needs of buildings.

Recent trends in low carbon buildings have utilised geothermal energy systems that – counter intuitively – use complex and energy intensive processes to generate energy. Earth tubes on the other hand, may require only a fan to move air through buried ducts that transfer energy indirectly from the ground.

Initial research carried out by the candidate revealed limited data beyond operational and simulated thermal performance. Most case study data focuses on the performance of earth tubes to partially pre-heat the outdoor air. However the candidate is investigating the potential for – and limits of – earth tubes to deliver 100% of the cooling requirements, by eliminating the need for expensive and energy inefficient air conditioning systems.

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