An analytical method to determine the amount of heat exchanged through thermally activated embedded retaining walls

Shallow geothermal energy is one of the most promising sources for producing clean energy that can be utilised for indoor heating and cooling systems. One of the methods to exploit this is through Energy Geostructures. These are the embedded portions of a structure that are thermally activated via heat exchanger pipes installed within them during construction. This allows them to exchange heat with the ground to satisfy the thermal demands of the building. Underground walls in contact with the ground can be converted to energy geostructures through inclusions of heat exchanger pipes. They are also known as Energy walls. Their large contact area allows them to exchange significant amounts of heat energy with the ground. Despite their potential, Energy walls lack a straightforward analytical method for thermal analysis, often relying on computationally expensive simulations or simplistic rules of thumb, both of which can compromise efficiency.
This thesis fills that gap by proposing an analytical method based on the planar nature of Energy walls. The base model for heat transfer in the ground around the walls is the infinite plane source (IPS), which is used to replicate planar heat transfer due to its one-dimensional behaviour. The IPS is applied through a method developed in this thesis called the Flux and IPS Splitting (FIS) method. This is combined with a length correction factor (LCF) and steady-state thermal resistivity for wall and pipe geometries to develop a comprehensive analytical method for thermal analysis. This method can assess the overall temperature changes in the wall, predict the temperature differences obtained in the fluid circulated in the pipes, and calculate the heat exchange rate with the ground. The FIS Method demonstrated a temperature prediction accuracy within 2%, indicating its accuracy. The thesis also provides guidelines for designing pipe arrangements in Energy walls based on this analytical method.