Sweden is a country that since long have prioritized the development of energy-smart solutions and the optimization of energy systems to reduce its energy consumption. Energy usage encompasses various needs, including heating buildings and premises, but most importantly, heating of residential properties. Today, nearly half of all heating is done through district heating, and the transition towards the idealization of this energy source is therefore crucial for future climate transitions. This development is now focused on a new generation of district heating technology called the fourth-generation district heating (4GDH). These technologies aim to reduce distribution temperatures from the current third-generation district heating technology (3GDH), which operates at 80-120°C in forward flow and 40-60°C in return flow, to 55-70°C in forward flow and 20-35°C in return flow.  The present report addresses what 4GDH may look like, with a focus on low-temperature district heating islands within an existing 3GDH network. The project is based on energy efficiency, competition from heat pumps, and recent customer demands, which necessitate the modernization of low-temperature networks to ensure the competitiveness of district heating. The objective of this work is therefore to gain an overview of the potential for improvement when establishing a low-temperature district heating network within an existing network, considering ecologic and economic perspectives. Using the programme NetSim, five different scenarios for conventional and low-temperature installations in Eskilstuna have been simulated. The results show that a low-temperature installation becomes significantly more expensive when only considering pipe prices, with economic losses amounting to approximately 1.05 million SEK in case 1 and around 0.91 million SEK in case 2. However, it was observed that the low-temperature networks in case 1 and 2 have significantly lower heat losses, primarily due to the material of the heat carrier but also the temperature difference in the pipes. An economic calculation was made, which revealed savings compared to the conventional network in each case, with profits of approximately 37 200 SEK and 24 400 SEK for each case, respectively. Regarding the assumed dimensioning, it is also evident that the hydraulic balance in the low-temperature networks is better than in the conventional one. In the lower temperature networks, temperature losses in the forward flow of up to 0.5°C and 0.6°C can be observed for case 1 and 2, respectively, while the conventional networks lose up to 6,4°C and 10,4°C. It can also be noted that there is a higher pressure drop in the low-temperature networks due to increased flow velocity to ensure power delivery. Furthermore, contact with Mälarenergi has confirmed that a hot water central system works well and should be utilized when switching from the primary network.

District heating plays a major part of the energy system used for heat supply in Sweden. The starting point of this parameter study have been to investigate the possibilities to provide the area Tullkammarkajen with efficient district heating supply in help of low temperature residual heat and waste heat from a nearby industry. The area is located in the city center of Halmstad and is currently in its planning phase. Facilities and apartments are planned to be built.The study is based on three different parameters: type of system, system temperatures and energy demand. The different type of systems that is analyzed is conventional districtheating, low-temperature district heating with a heat pump as a complement as well as low-temperature district heating with the primary network’s feed line as a complement. Further comparison was made between these parameters, both from an energy wise perspective as well as from an economic perspective.The underlying idea to this study has been to obtain an energy efficient solution that at the same time suits the principle of sustainable development. However, it can clearly be seen in the presented results that it is more profitable to use more conventional methods that are not adapted to sustainable development, based on today’s market. Thus, the question becomes whether the future of innovative solutions or economical funds should be prioritized.