The increased use of heat pumps to utilise low-temperature heat will undoubtedly be a part of future emission reduction measures within the heating sector. Identifying these heat sources and assessing their heat potential is essential for their utilisation. Different methods for estimating the potential of excess and natural heat sources found in the urban environment are presented in this study. The research aims to present a replicable estimation methodology which can be applied to any urban area. The methods are developed around publicly available data sources, or otherwise easily obtainable data. The research aims at producing data accurate enough to support decision-making on the district heating company or city level on utilising these heat sources. A wide range of excess and natural heat sources found in urban environments were identified in a literature review. Methods for estimating the potential of the heat sources were developed based on findings of the literature review and the expected availability of data. The developed estimation methods were applied in a case study where the potential of heat sources identified within the Turku area in Southwest Finland was estimated. The results of the case study show the potential of the heat sources within the studied area. The difficulty of obtaining raw, high-quality data are also highlighted. This emphasises the need for advanced processing of available data and insight on the related sources, e.g. building management systems or industrial processes. The methods presented in this study give an overview on how heat potential could be estimated. It can be used as a base for developing more refined methods and for detailed techno-economic assessment for utilising available excess and natural heat sources.