Assessing the Cooling Potential of Tailing Piles for Urban Heat Mitigation in Germany’s Ruhr Metropolitan Area—A Case Study of the Rungenberg in Gelsenkrichen

Abstract

Elevated air temperatures in cities with potential negative effects on, e.g., residents are a major challenge for urban planning. Open green spaces on hills where at night air can cool and drain into residential areas are of great importance to ameliorate the heat load in urban areas. In the Ruhr Metropolitan Region in Germany, tailing piles from the former coal mining industry offer a previously neglected potential for cooling neighbourhoods. The genesis and drainage of cold air on tailing piles have not been extensively investigated so far. Tailing piles are often located in or nearby residential areas and are exposed as open spaces, where cold air can build up and drain into the surrounding neighbourhoods due to their slopes. In the present study, the genesis of cold air and the cold air drainage are empirically investigated using thermal infrared imagery and air temperature measurements during one night in 2019 at the Rungenberg tailing pile in Gelsenkirchen. Furthermore, the cooling effect on the adjacent residential area, Schüngelberg, was studied. The results indicate that cold air builds up at Rungenberg and drains into Schüngelberg. However, the cold air flow into the residential area was blocked by a brick wall located at the foot of the Rungenberg tailing pile. More awareness should be given to the cooling potential of tailing piles, and urban planners should improve this cooling potential by keeping tailing piles open and removing barriers located in the drainage pathways in order to alleviate urban heat.