Energy-economic assessment of reduced district heating system temperatures

Geyer, Roman; Krail, Jürgen; Leitner, Benedikt; Schmidt, Ralf-Roman; Leoni, Paolo

doi:10.1016/j.segy.2021.100011

Cited by 19 publications

(1 citation statement)

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“…It also provides cooling, or low return temperature, to the heating circuit, which increases the efficiency and capacity of DH. This can also increase the quantity of heat extracted from energy sources, such as condensing gas boilers, solar panels [65], geothermal heat pumps, industrial waste heat and Combined Heat and Power (CHP) [66].…”

Section: Benefitsmentioning

confidence: 99%

Challenges for the Transition to Low-Temperature Heat in the UK: A Review

2021

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To reach net-zero emissions by 2050, buildings in the UK need to replace natural gas boilers with heat pumps and district heating. These technologies are efficient at reduced flow/return temperatures, typically 55/25 °C, while traditional heating systems are designed for 82/71 °C, and an oversized heating system can help this temperature transition. This paper reviews how heating systems have been sized over time in the UK and the degree of oversizing in existing buildings. It also reviews if lessons from other countries can be applied to the UK’s building stock. The results show that methods to size a heating system have not changed over time, but the modern level of comfort, the retrofit history of buildings and the use of margin lead to the heating system being generally oversized. It is not possible to identify a specific trend by age, use or archetype. Buildings in Scandinavia have a nascent readiness for low-temperature heat as they can use it for most of the year without retrofit. Limitations come primarily from the faults and malfunctions of such systems. In the UK, it is estimated that 10% of domestic buildings would be ready for a supply temperature of 55 °C during extreme external conditions and more buildings at part-load operation. Lessons from Scandinavia should be considered with caution. The building stock in the UK generally underperforms compared to other EU buildings, with heating systems in the UK operating at higher temperatures and with night set-back; the importance of providing a low-return temperature does not exist in the UK despite being beneficial for condensing boiler operation. Sweden and Denmark started to develop district heating technologies with limitations to supply temperatures some 40 years ago whereas the UK is only just starting to consider similar measures in 2021. Recommendations for policy makers in this context have been drawn from this review in the conclusions.

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Section: Benefitsmentioning

confidence: 99%