The research aims to develop the methodology for waste heat implementation into the district heating systems by overcoming several barriers. The waste heat from different enterprises has been identified as an important thermal energy source in smart energy systems for the heat load coverage by using heat pumps. First, waste heat potential mapping eliminates the lack of information. The authors have developed a detailed assessment of the largest enterprises, their heat production levels, and the distance to the nearest district heating plant for the Latvia case study. The approach highlights the national techno-economic potential of waste heat, which has been further used for dynamic simulation of waste heat integration into the district heating systems. When allocating the techno-economic waste heat potential with existing heat demand, it can be concluded that 83 GWh or 31% of overall waste heat could be used in DH systems. The cost-benefit analysis is performed by analyzing the main income and cost flows. The total amount of waste heat potential in the rural areas is around 38 GWh per year. Even though this amount of waste heat cannot be used in DH networks, there is potential for industrial symbiosis between several different manufacturing companies to use waste heat efficiently.