Energy Efficiency in Buildings
The analysis of the thermal envelope of the buildings of Torrelago highlighted the existence of significant thermal losses, thus it was necessary an energy efficient retrofitting of the building envelopes of the 31 buildings of the district to achieve high-energy performance and better internal comfort in the dwellings.
The building retrofitting reduced the energy demand of the district by implementing an Exterior Thermal Insulation Composite System (ETICS). The solution consisted of the installation of 8 cm-thick panels of expanded polystyrene (EPS) on the exterior side of the existing façade.
The original façade, with a width of 25.5 cm and a U-value of 1.36 W/m2K, was retrofitted with a new resulting wall of 35 cm and a U-value=0.34 W/m2K. The adopted solution is even more energy-efficient than the requirements of the Spanish Technical Building Code (U-value ≤ 0.66 W/m2K) ensuring a significant reduction of the energy demand.
Energy Systems
District Heating
The old district heating system was composed of two independent networks supplied by gas-fired boilers. One district heating network provided thermal energy for 12 buildings (Phase I) and the other district heating network provided thermal energy to the other 19 buildings of the district (Phase II).
A full renovation of the existing district heating was carried out and a new centralized power biomass plant generation and an efficient distribution system were installed. In order to increase the overall performance of the energy system, a set of measures were implemented:
- The installation of a new biomass thermal plant with a thermal output of 3.5 MW (three new high efficiency biomass boilers)
- The construction of a new buried building to locate the biomass boiler room and the biomass silo
- The existing independent networks were merged into a new distribution system
- The installation of new heat exchange substations at building level for the buildings of Phase I; Phase II counted already with heat exchanger substations.
The partial substitution of the gas boilers with new biomass boiler aims to cover the 80% of the energy consumption with renewable resources. Some of the gas boilers are maintained in a second boiler room as a reserve for use at peak and potential failures or outages biomass periods.
Cogeneration (CHP)
A micro cogeneration system (thermal output of 71,6 kW and electric output of 33 kW) was installed in order to contribute to increase the ratio of energy supplied by renewable resources in the district. The energy supplied by the micro cogeneration system should have covered partially the energy consumed by the thermal and electric installations. Actually, the micro cogeneration system is installed but it is not working due to a number of administrative barriers.
ICT
The implementation of a set of energy conservation measures was planned together with a newintegrated energy management systemin order to monitor and check constantly the performance of the whole system, from the generation system to the dwelling level. The control system of the facilities allows to optimize the performance of the district through the monitoring of real-time data and adjust the operation of the system according to the needs.
DEMS (District Energy Management System)
An advanced control system was developed for the management of district heating system, using a communication architecture distributed in star topology. Control panels were implemented and information at generation and distribution level from the district heatingis gathered.
BEMS (building Energy Management System)
The BEMS monitors the energy flows in each of the buildings in the Torrelago district. All the information related to the exchange substations for the management of heating and domestic hot water (DHW) in each building is collected.
HEMS (Home Energy Management System)
Smart meters, thermostats, cut-off valves and other devices have been installed at dwelling level. This system allows to know the energy consumption and the behaviour of each dwelling. In addition, it provides the opportunity to get the involvement of the residents. The residents can manage the comfort temperature at their homes and be aware of their thermal and electrical energy consumption. The new system provides residents with useful information to make decisions towards a more efficient use of the energy.
Monitoring platform and visualisation tools
The information supplied by KPIs enables to validate the energy performance of the district. Furthermore, the visualisation tools are a valuable instrument for different stakeholders, e.g. promote awareness about energy consumption within the residents, provide useful information to the energy company or to the responsible of the maintenance.