Thermo-hydrological behaviour of green infrastructure: A comparative field and laboratory study

Abstract

Heat recovery and dissipation using shallow, buried exchangers are a recognised cost-effective and renewable alternative to using fossil fuels for space heating and cooling. The efficiency of such ground heat exchangers (GHE) is dictated by the bulk thermal properties of the soil. These are heavily influenced by the soil hydrological regime, which is driven by soil–atmosphere interaction. The typically moist substrate profile of Sustainable Drainage Systems (SuDS), which are designed to possess and maintain a high infiltration and storage capacity, have significant potential as a medium for shallow GHEs. An at-scale field setup was commissioned in this study to monitor the thermo-hydrological behaviour of SuDS. Comparable results to laboratory measurements in terms of soil water retention and thermal conductivity dryout curves were obtained. Furthermore, field measurements indicate that the substrate in the field setup remained in the high thermal conductivity range, even under summer conditions. The conductive substrate and saturation conditions prevalent in SuDS presents an attractive opportunity to address our cities’ increasing energy demand under a changing climate.