New possibilities for ultra-low temperature district heating in corporate district heating networks

Tecnalia coordinates the RELaTED project which aims to develop an innovative concept of decentralised ultra-low temperature district heating networks. This new concept will be tested in four demonstrations sites, in Denmark, Serbia, Estonia and Spain.

The Spanish project is located in Iurreta, in the North of Spain. This site is owned by the Department of Security of the Basque Government. The base consists of a total of thirteen buildings with different architectonic design and use profiles including administrative buildings, sports facilities, workhouses and other constructions for residential use.

In Iurreta there is a district heating network that supplies energy for heating and domestic hot water services to the buildings. Heat is produced by two condensing boilers with a total capacity of 650 kilowatts. The system is designed for operating at 80 degrees.

Based on this scenario, the intervention proposed in the frame of the RELaTED project aims to evolve to an ultra-low temperature district heating system where renewable and waste heat sources could also take part.

To achieve this main goal, proposed interventions include:

• The adaptation of the system facilities to operate at lower temperatures.
• The connection of reversible heat pumps to the ultra-low temperature networks will allow rising the thermal level where existing terminal units provided higher temperatures.
• The incorporation of solar energy as an additional energy source in the district.
• Enable the installation for using the reminding heat arising from heat pumps during summer.

This new ultra-low temperature district heating is expected to be operational in 2021.