Monitoring of thermo-hydrological behaviour in Green Infrastructure

The multi-purpose nature of Sustainable Drainage Systems (SuDS) or Green Infrastructure (GI) presents a significant opportunity to store or recover heat for low carbon urban heating/cooling systems. The capacity of such systems for energy storage is strongly dependent on the thermal and hydrological boundary conditions, estimation of their feasibility requires a deep understanding of how atmospheric conditions and the near-surface hydrological regime affect heat transfer. A large-scale, outdoor lysimeter has been set up at the (UK) National Green Infrastructure Facility in order to monitor the influence of atmospheric conditions on hydrological and thermal properties of SuDS. Volumetric water content, matric suction and temperature were monitored at various depths and locations within the sand and topsoil layer. Additionally, thermal conductivity at multiple depths, and heat flux at the surface and bottom boundary were measured. Results of the initial monitoring phase, as well as, preliminary laboratory tests are presented herein and demonstrate the complex interaction between partial saturation and heat transfer. Further work investigates the effects of rainfall and heat injection using rainfall simulation and a variable-power heating cable, respectively.