This report presents the work performed in Task T1.2 of the ReUseHeat project to assess the accessible EU28 urban excess heat recovery potential from four unconventional excess heat sources: data centres, metro stations, service sector buildings, and waste water treatment plants. The report presents in overview and detail the concepts, data, basic premises, and methods, used to produce the results from this work. In all, excess heat potentials are modelled and spatially mapped for a total of some 26,400 unique activities, but by application of two new concepts: available excess heat and accessible excess heat, by which total potentials are distinguished from practical utilisation potentials, a significantly reduced count of some 6800 unique facilities represent the final cut. Common for these facilities are that they all are located inside or within 2 kilometres of urban district heating areas. For the total count of activities, the full available excess heat potential is assessed at some 1.56 EJ per year. At the restrained conditions, thus representing a conservative estimate, the final available excess heat potential from the four unconventional sources is estimated at 0.82 EJ per year, which here corresponds to a final accessible excess heat potential anticipated at 1.24 EJ annually.