Factors influencing the environmental and economic feasibility of district heating systems - A perspective from integrated spatial and energy planning

Abstract

Background: District heating systems have been gaining importance in the last years. However, local circumstances, e.g. regarding heat demand and available heat sources, are diverse and new technologies especially in the low-temperature sector arise. Central aim of this research is to identify the impact of integrated spatial and energy planning on the environmental and economic sustainability of district heating systems, to distinguish between more and less appropriate areas for district heating and to build the basis for a low-barrier decision tool for local authorities regarding the identification of areas suitable for district heating, also showing spatial planning strategies to enhance the opportunities for district heating. Future changes until 2050 are analysed and planning principles derived; therefore, unpredictable parameters such as energy prices and subsidies are not included in this research. Methods: Based on the system analysis according to Vester, a modified method was developed. The following research fields were involved: spatial planning, resource management, environmental planning, and energy and building technology. Results: As main integrated spatial and energy planning aspects relevant for district heating, mix of functions, potential of compacting and extension, density of buildings, inhabitants and employees, building type, thermal insulation potential, and the used heat source(s) were identified. By steering these parameters, the feasibility of district heating systems can be enhanced. Indicators, directly linked to the feasibility of district heating systems are energy consumption density, number of annual full load hours, temperature level, and available heat source(s). Climate change, changes in building density, thermal insulation, and the mix of functions will influence district heating systems regarding environmental and economic aspects. Reduced heat consumption can be a threat to district heating systems, but can be balanced by decreasing inlet temperatures, making waste heat and renewables accessible. Conclusions: As district heating systems are often advantageous to other forms of providing heat due to higher resilience, the economies of scale effect, or the potential of using energy surpluses ('waste heat'), spatial planning policies must seek ways to provide for adequate building density and to enhance the mix of functions in order to ensure the long-term feasibility of district heating systems.