Manual for cutting district heating temperatures
Reducing the temperature of a district heating system is financially beneficial but few energy companies are actively working on doing so. FVB – on behalf of Energiforsk – has produced a manual as a guide to how district heating companies can effectively reduce supply and return temperatures.
The temperature levels of most Swedish district heating grids have been about the same for the last 20 years, despite the fact that it would be well worth it financially to reduce the temperature. Money can be saved by increasing the yield of flue gas condensers and lower distribution losses, thus cutting expensive peak demand production.
“But with the high biofuel prices, we can now see that there is more interest in cutting temperatures in district heating systems,” says Cilla Dahlberg Larsson at FVB, who co-wrote the manual with her colleagues Ulrika Sagebrand and Thomas Nordin.
Money to be saved
Higher biofuel prices also mean that district heating companies are looking at alternative fuels, and there is considerable interest in using surplus heat and long-term storage. However, many sources of surplus heat have lower temperatures than those found in current district heating systems, but by cutting those temperatures, more sources of surplus heat can be used. By lowering the difference between the surplus heat and system temperatures, the criteria for using heat pump solutions are improved.
“There have been good financial arguments for cutting temperatures before, but we can now see they are gaining considerable weight. That’s due to fuel prices rising steeply and the costs of other heat sources such as surplus heat, solar power, heat pumps and long-term storage becoming lower, if the district heating system’s temperature level is lower,” says Dahlberg Larsson.
According to the IEA report “Low-Temperature District Heating Implementation Guidebook”, the financial arguments for lower temperatures will improve five-fold compared to current levels.
Cilla mentions three measures that are key to being able to cut the temperature in a district heating system. Faults have to be identified and dealt with in customer heating control systems and internal heating systems, unnecessary circulation flow must be identified and minimised, and the supply pipe temperature needs to be reduced to the optimum level in different operating scena

Successful solutions
The manual also presents examples of how three energy companies successfully worked with the recommendations.
“Take a look at how companies who successfully addressed these issues organised themselves to prioritise the work, as this is a vital issue,” recommends Dahlberg Larsson.
The “Handbok för sänkta fjärrvärmetemperaturer” (manual for cutting district heating temperatures) can be downloaded free from www.energiforsk.se
For more details, contact:
Cilla Dahlberg Larsson, +46 (0)31 10 60 86

Luleå Energi has worked systematically to cut over-consumption of district heating flow in its grid. Photo: Luleå Energi.