The DH system in Brescia, owned and operated by A2A Calore e Servizi, is the largest DH system in Italy, with more than 1 TWh annual supply and covering about 70% of the town heat demand. The oldest part of the network started operating in 1972 and today more than 60% of the heat is produced by a waste-to-energy plant.
The network delivers heat to more than 21.000 customers. The trench length is 380 km (+292 km customer connections).
Owing to the high operating temperatures, up to 130 °C in winter, the annual heat losses are rather high. For this reason, there is a high interest in reducing the network temperatures, at least in low-density areas.
The main bottlenecks to lower temperatures lie on the building side and depend typically on the heat demand, the heating system, the control function, the connection size, and the customer behavior.
The selected demo site is located on a peripheral branch in the southern part of the network. The site includes 35 customers (1 large multi-family house and 34 single-family terraced houses) with a total contract capacity of about 700 kW. This site was selected considering also the large replicability potential, since it is representative of several sites in European district heating networks.
A successful temperature reduction reached through replicable solutions is expected to pave the way to a more competitive and sustainable district heating, with higher efficiency and hosting locally available low-temperature and low- or no-carbon sources, whose integration can become economically feasible once the system temperatures are lowered.
In this demo site, the temperature reduction will be demonstrated by integrating the solution package 3 and by engaging the end costumers. The solution package 3 consists of following solutions:
• Supervision ICT platform
• Visualisation tools
• Smart DHC controller
• Optimisation of building installation
For the site preparation, old dismissed gas boilers close to the multi-family house were removed, with consequent re-qualification of the area aesthetics, and replaced with a container hosting a supply-to-return mixing station. Here, the hot water from the main network is mixed with the return (in a ratio depending on the ambient T) to get a colder supply to the demo site.
Sensors to monitor the indoor temperatures were placed in some buildings, and hardware tools communicating with a cloud were installed to transmit the operating data and enable the smart control.
The temperature reduction started on January 2020. The first results showed that reducing the site supply temperature by 15 °C is technically feasible and it does not compromise the heat supply. Customer engagement was an important and successful step for the acceptance of lower supply T and for the sensor installation in the buildings; it included delivery of letters, flyers, and a public assembly with customers and local authorities. A detailed report of the first results from the integrated innovations is freely available here.
For the heating season 2020/2021, an additional effort for a further temperature reduction of both supply and return line is planned. It includes actions of the smart controller on both the primary and secondary side.