District heating and cooling systems can aid in decarbonisation and the provision of efficient heating and cooling in Europe. However, whereas these systems have achieved high penetration rates in colder climates of Northern, Central and Eastern Europe, they remain marginal in milder climates of Southern Europe. In terms of network design, district heating and cooling systems can be configured in different ways. In so-called warm networks, the required temperature for all the consumers is attained city-wide, and in so-called cold systems, the necessary temperature is achieved at the consumers' premises by ancillary equipment. The most cost-effective heating and cooling solution for urban areas requires investigation. This research models and compares cold and warm district energy systems with other heating and cooling solutions through a comprehensive case study executed in the city of Bilbao, Spain. The city is characterised by a mild climate and a high population density which is characteristic of many Southern European cities. The results show that district energy systems are economically advantageous compared to other low-carbon solutions, such as air-source heat pumps. However, these systems are not able to outcompete natural gas under current cost and taxation levels. Warm networks provide a cheaper source of heat compared to cold networks, but both network types lead to similar expenditures for combined heating and cooling supply. This paper, presents the study context and its results, and is complemented by an exhaustive detailed methodology document and a separate supplementary material repository. © 2024 The Authors

The transition to a more sustainable energy system with a growing amount of intermittent renewable energy sources brings an increasing need for flexibility measures to maintain balance between supply and demand. Buildings represent a promising source of demand-side flexibility due to their large energy demand and thermal mass. This review provides insights into the storage potential of building thermal mass, and the benefits and challenges it brings. It is found that building thermal mass storage have good ability to shift loads on short term, from peak to off-peak hours. This ability can be utilized for different purposes, for instance reduced costs for end-users or energy providers, reduced primary energy demand, or reduced CO2 emissions. Furthermore, this review explores different factors that influence the storage potential of building thermal mass, with special attention paid to the heat emission system. It is shown that hydronic floor heating is beneficial compared to radiators since it directly can activate the thermal mass with smaller impact on the indoor temperature. It is also found that the factor with largest impact is the envelope insulation level; increased insulation level brings improved storage efficiency and prolonged thermal autonomy but also decreased storage capacity and increased risk of overheating. Finally, research gaps are identified. © 2023 The Authors

District heating is one of the technologies that can contribute to the decarbonisation of the European heat sector. Nonetheless, these infrastructures only deliver about a tenth of the heat demands in the continent. Therefore, it is essential to assess the expansion potential of these systems and to identify which areas should be target for further investigations, which calls for easy-to-use and straightforward methods such as Persson & Werner's network capital cost model. Pivotal parameters of the model are the effective width, a metric of trench length by land area, alongside the average pipe diameter and the linear heat density. This study has carried out an in-depth analysis of these crucial parameters with respect to both distribution and service pipes in a large Danish district heating network, which has allowed to explore the behaviour of effective width in a broad range of building densities and derive new equations for both effective width and average pipe diameter. The model has subsequently been validated in another large network in Denmark and several minor districts in the same country, showing the accuracy of the model on an aggregated level. © 2023 Elsevier Ltd.

The decarbonization of the heat supply and the attainment of a higher security of supply demand the transition towards zero-carbon heating solutions. In dense urban environments, where the construction cost of a pipe network is relatively low, heating and cooling networks can deliver heating and cooling at a lower cost compared to individual solutions. 

This paper builds on prior research by these authors mapping heating and cooling energy use in Bilbao, Spain, a city characterised by mild oceanic climate and a dense urban pattern. Areas within the city where heating and cooling networks could be more feasible have been identified taking into account the building stock characteristics and energy use, together with other urban and resource parameters, and a city district has been selected for further study.      

Warm networks deliver heat at a sufficiently high temperature to be directly used by the consumers whereas cold networks employ lower temperatures, thus requiring heat pumps at the consumers premises. Research has highlighted as advantages of this newer configuration the possibility of delivering both heating and cooling with the same network, the lower capital costs of these networks and negligible heat losses. Nonetheless, comparisons between the two technologies have been seldom performed in the literature. In this paper, an economic comparison between these two solutions is presented for the selected district of Bilbao.  Results show that cold networks require a lower investment in the actual network infrastructure but the distributed heat pumps increase the costs to a higher total CAPEX than in warm networks.  Overall life cycle costs of heat are also slightly higher for cold networks than for warm networks. Other benefits and barriers for each of the solutions, for example regarding necessary space or speed and modularity of the implementation of the network are also discussed.

This report aims to present the results of the work carried out within the sEEnergies project pertaining to estimating construction costs of new district heating networks in France.

This project has followed a similar methodology to Heat Roadmap Europe when estimating the costs of district heating systems. Nonetheless, several improvements have been introduced to attain more realistic results. On the one hand, it has been carried out a detailed geographic analysis of two large Danish networks so the necessary pipe length can be better appraised. Moreover, both the distribution network and service pipes have been taken into consideration. On the other hand, pipe construction cost data from each country has been used to the maximum extent possible.  

This part of the project has only focused on the pipe network and has not taken into account other elements for the development of a district heating system, such as heat supply plants or the connections to the heat demands via a substation. 

The results for France show that the country has a significant potential for District Heating expansion. Approximately a quarter of the total heat demand (28%) could be supplied with a cost lower than 20 €/MWh and nearly half of the heat demand (47%) would be economically viable with a higher marginal cost of 30 €/MWh. Nonetheless, there is significant regional variation. For instance, for a marginal cost threshold of 20 €/MWh, Paris could cover nearly the entire heat demand and the other départements of the petite couronne de París, could reach penetration rates above 70%. On the contrary, the 12 least dense départements would not be able to deliver more than 10% of the heat demand, having the département of Vendée the lowest potential with merely 3%. 

This report aims to present the results of the work carried out within the sEEnergies project pertaining to estimating construction costs of new district heating networks in Germany.

This project has followed a similar methodology to Heat Roadmap Europe when estimating the costs of district heating systems. Nonetheless, several improvements have been introduced to attain more realistic results. On the one hand, it has been carried out a detailed geographic analysis of two large Danish networks so the necessary pipe length can be better appraised. Moreover, both the distribution network and service pipes have been taken into consideration. On the other hand, pipe construction cost data from each country has been used to the maximum extent possible.  

This part of the project has only focused on the pipe network and has not taken into account other elements for the development of a district heating system, such as heat supply plants or the connections to the heat demands via a substation. 

The results for Germany show that the country has a significant potential for District Heating expansion. Approximately a quarter of the total heat demand could be supplied with a cost lower than 20 €/MWh and nearly half of the heat demand would be economically viable with a higher marginal cost of 30 €/MWh. Nonetheless, there is significant regional variation, and whilst the most urban districts (kreise) could reach penetration rates above 70% for a marginal cost of 20 €/MWh, the least dense would fall below 10% of the heat demand. 

The decarbonization of the heat supply and the achievement of a higher energy security calls for the substitution of conventional fossil fuel boilers by other means of heat supply. In dense urban areas, where the pipe network cost is proportionally lower, district heating can be an attractive solution for this goal. If there is a possibility to recover heat that would otherwise be wasted or produce renewable heat centrally in a more economic manner, this can be a very cost-effective solution for decarbonising the heat supply. Networks for district heating have traditionally distributed heat at a temperature sufficiently high to virtually all consumers. In cold district networks , the network is maintained at close to ambient temperature (10-30°C), and require the heat to be boosted at the consumer level. Cold networks have drawn plenty of research attention thanks to several advantages such as their capacity to provide with the same network both heating and cooling or using more economic piping.  Nonetheless, comparisons between the two technologies have been seldom performed in the literature. This study has aimed to fill this gap and has drawn an economic comparison between these two solutions in a case study for the city of Bilbao, which presents a mild oceanic climate but features a very dense urban fabric. 

District heating is an important technology for decarbonizing the heating supply in urban areas since it enables the recovery of waste heat that would otherwise be wasted and the cost-effective utilization of renewable heat. Nonetheless, the current general extent of these systems in Europe is very low, hence the need for simple methods and parameters to estimate their cost and feasibility on a large scale. One of these cost parameters is the Effective Width, which enables a first order approximation of the total pipe length in a given area. This concept, in conjunction with the average pipe diameter in the area, permits the determination of the network’s capital cost. However, previous research of Effective Width has relied on a small set of cases and has not contemplated service pipes. Therefore, there is need for a closer look and a deeper understanding of the underlying phenomena that influences this parameter. This study has analysed several Scandinavian District Heating Systems in detail and provides new evidence on the relation between Effective Width and the urban environment for both distribution and service pipes.