Low-temperature operation of heating systems to enable 4th generation district heating: A review. (1st June 2022)

• Record Type: Journal Article
• Authors: Østergaard, Dorte Skaarup; Smith, Kevin Michael; Tunzi, Michele; Svendsen, Svend
• Is Part Of: Energy. Volume 248(2022)
• Publication Date: 2022-06-01
• Subjects: Low-temperature district heating -- Hydronic heating systems -- Energy renovation -- Digitalisation and fault detection in heating systems -- Heating efficiency; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2022.123529
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: District heating networks increasingly rely on heat pumps, condensing biomass boilers, and excess heat in the transition to sustainable energy systems. Accordingly, district heating operators seek to reduce their networks' supply and return temperatures to maximise production efficiencies, minimise heat losses from distribution pipes and allow greater utilisation of renewable heat sources and excess heat. Experts have predicted that investing in solutions that reduce heating temperatures in buildings will yield a return on investment of 300% for district heating operators. Therefore, expecting incentives, building operators should identify methods to reduce supply and return temperatures to enable a rapid, widespread transition to low-temperature district heating. Ample research has investigated and documented the feasibility of low-temperature heating in buildings, and this paper presents the first comprehensive review. It synthesises available literature and adds new perspectives to help guide future implementation, research and development of low-temperature heating. The energy and temperature demands of various heating systems provides a background, leading to a review of typical malfunctions and their impacts. The article subsequently reviews the obtainable supply and return temperatures before and after renovating the building envelope and heating systems. It further identifies and summarises vital measures for decreasing heating system temperatures. Ultimately, the authors recommend minimising heating system temperatures using automatic balancing of space heating and ventilation systems, novel solutions for safe domestic hot water supply, and digitally-enabled performance monitoring and optimal control. Highlights: Review of the energy and temperature demands for various heating systems. Review of typical heating malfunctions in buildings served by district heating. Review of the obtainable supply and return temperatures pre- and post-renovation. Review of technical improvements to achieve low-temperature operation in buildings. Key prospects and research areas for improving low-temperature heating systems.