Ground heat exchange potential of Green Infrastructure

Both Green Infrastructure and Ground Source Heat Exchangers provide opportunities to significantly improve the resilience and sustainability of our built environment. This work explores the thermo-hydrological response of a vegetated Sustainable Drainage System under physically simulated heat injection conditions using a soil column of 1800 mm diameter and 950 mm height in a heavily-instrumented lysimeter. A range of field testing scenarios (thermal load and cycling) were applied under natural, external ambient conditions. Soil temperature during heat injection was also simulated numerically by solving a transient heat conduction equation with a finite difference modelling scheme. The developed model was validated using measurements from the lysimeter setup which then enabled numerical experiments into the effects of varying hydrological regimes to be performed. Results of the field testing showed that heat injection propagates a temperature change only at deeper layers, while the temperature of shallow layers are still governed by the atmospheric conditions. [Display omitted] •Heat injection into green infrastructure has been tested.•Exchanger zone of influence does not reach shallow depth.•Even with injected heat, ambient air temperature governs ultimate offtime soil temperatures in daily and prolonged operation.•Numerical model, validated with field measurements, showed a slightly more efficient heat transfer with increased water content.