This paper presents an assessment of the excess heat recovery potential from EU metro stations. The assessment is a sub-study on low temperature recovery opportunities, explored in the H2020 ReUseHeat project, and consists of spatial mapping of 1994 underground stations with quantitative estimates of sensible and latent heat, monthly and annually, attainable in rejected platform ventilation exhaust air. Being a low-temperature source, the assessment conceptually anticipates recovery of attainable heat with compressor heat pumps to facilitate the temperature increase necessary for utilisation in district heating systems. Further, the paper explores the influence on useful excess heat volumes from low-temperature heat recoveries when distributed at different temperature levels. The findings, which distinguishes available (resource) and accessible (useful) excess heat potentials, indicate an annual total EU28 available potential of ~21 PJ, characterised by a certain degree of seasonal temporality, and corresponding accessible potentials of ~40 PJ per year at 3^rd generation distribution, and of ~31 PJ at anticipated 4^th generation conditions. Despite lower accessible volumes, utilisation in 4^th generation systems are naturally more energy efficient, since relatively less electricity is used in the recovery process, but also more cost-effective, since heat pumps, at lower temperatures, can be operated at capacities closer to design conditions and with less annual deviations.