Alessandro Dalla Rosa

The decreased heating demand in low-energy buildings affects the cost-effectiveness of traditionally-designed district heating (DH) systems. This paper presents the innovative low-energy DH concept, which is based on low- temperature operation. The annual energy performance of a low-energy network for low-energy houses in Denmark was investigated. We considered the influence of the human behavior on the energy demand, the importance of the degree of buildings connected to the network and a socio-economical comparison with ground source heat pumps. In the North European climate, the human behavior can lead to 50% higher heating demand and 60% higher heating power than expected according to reference values in standardized calculation of energy demand pattern in energy-efficient buildings. Next, we proved that low-energy DH systems are robust systems that ensure the security of supply to each customer in a cost-effective and environmentally friendly way in areas with linear heat densi...

The paper describes the Danish contribution to the IEA-ECBCS Annex 51: “energy efficient communities”. We present three case studies, two from Annex subtask A (state-of-the-art review) and one from subtask B (ongoing projects). The first case study is “Samsoe: a renewable energy island”. The community achieved a net 100% share of renewable energy in its total energy use, relying on available technical solutions, but finding new ways of organizing, financing and ownerships. The second project is “Concerto class I: Stenloese Syd”. The buildings in the settlement are low-energy buildings class I (Building Regulation 2008). The project partners envisaged the implementation of selected key energy-supply technologies and building components and carried out an evaluation of user preferences to give suggestions to designers and constructors of low-energy houses. The third case study (Subtask B) is: “low-energy neighbourhood in Lystrup, Denmark”. The project integrates sustainable solutions ...

The future will demand implementation of C02 neutral communities, the consequences being a far more complex design of the whole energy system, since the future energy infrastructures will be dynamic and climate responsive systems. Software able to work with such level of complexity is at present a missing link in the development. In this paper is demonstrated how a link between a dynamic Building Simulation Programme (BSP) and a simulation program for District Heating (DH) networks can give important information during the design phase. By using a BSP it is possible to analyze the influence of the human behaviour regarding the building and link the results to the simulation program for DH networks. The results show that human behaviour can lead to 50% higher heating demand and 60% higher peak loads than expected according to reference values in standardized calculation of energy demand. The analysis also shows that the connection of low-energy buildings to DH networks is potentially...

Background and ObjectiveThe evolution of district heating (DH) has gone through three generations since the first introduction of distirct heating. It is characterized by the type of transport media and the network temperature levels: the 1st generation DH system is steam-based system, the 2nd generation DH uses high network supply temperature above 100oC, and the 3rd generation DH represents the current DH system with medium network supply temperature between 80oC to 100oC. Up until now, the 4th generation DH as the low-temperature district heating (LTDH) is emerging as a new system which is going to replace the existing 3rd generation DH system. Comparing with the existing DH system, the LTDH reduces the network supply temperature down to consumer required temperature level, thus greatly improves the quality match between the energy supply and the energy demand. Meanwhile, LTDH coupling with reduced network temperature and well-designed DH network can reduce network heat loss by u...

The low-energy district heating concept has the potential of increasing the energy and exergy efficiencies of heat supply systems and of exploiting renewable energy, provided technical solutions for its wide application can be developed and implemented. This article investigates the dynamic behaviour of district heating branch pipes in low-temperature operation (supply temperature 50–55°C and return temperature 20–25°C). We looked at

ABSTRACT Using a bypass to redirect a small flow through the in-house DH (district heating) substation directly to the return pipe is a commonly used but energy-inefficient solution to keep the DH network “warm” during non-heating seasons. Instead, this water can be redirected to the bathroom FH (floor heating) to cool down further and thus reduce the heat lost from bypass operation while tempering the bathroom floor and guaranteeing fast provision of DHW (domestic hot water). We used the commercial software IDA-ICE to model a reference building where we implemented various solutions for controlling the redirected bypass flow and evaluated their performance. The effect on the DH network was investigated using Termis software. Bypass flow redirected into bathroom FH during the non-heating period resulted in comparison to the reference case on average in a 0.6 °C–2.2 °C increase of the floor surface temperature and additional cooling of bypass water by 3.9 °C, reducing the heat loss from the DH network by 13% and covering 40% of the heat used in the bathroom FH. The use of the bypass flow in bathroom FH is a cost-effective solution exploiting the heat that would otherwise be lost in the DH network to improve comfort for customers at discounted price.