Energy Networks in Sustainable Cities
The POLICITY project dealt with different aspects of urban development: new construction and tr-generation energy supply in Cerdanyola del Valles at the city edges of Barcelona (Spain); the conversion of an old city quarter in Turin (Italy) with energy distribution based on the heating network and with thermal cooling; and new building constructions on a large former military ground in the town of Ostfildern near Stuttgart (Germany) with biomass heat and electricity supply.
The most important measure in the Scharnhauser Park in Ostfildern was the optimisation of a new biomass plant (combined heat and power). About 80% of the heating energy demand and 50% of the electricity consumption of the whole area is supplied by this plant with 1 MW electrical and 6.3 MW thermal power. One of the innovative targets was to use residual heat to cool office buildings in summer. Furthermore, all buildings were equipped with optimal heat insulation to minimize heat loss in winter.
For the Cerdanyola site in Barcelona, experience in the demonstration buildings has created important added value in relation to adapting the interaction policy of the Public Housing Authorities. The know-how generated in the three POLYCITY Catalan buildings’ life cycle (design, works and use) is especially interesting in the implementation of the new EU Directive related to Energy Performance in buildings. The experience and results are significant on two levels:
- Reduction of energy demand and C02 emissions due to the passive measures,
- Increased environmental awareness and more responsible energy use by tenants due to an innovative interaction model.
The energy savings in the 3 demo buildings was over 70%, In terms of C02 emission reductions, the results in residential buildings are about 8Kg C02/m2/year. These results show the effectiveness of the demonstration measures that could be considered very replicable, especially the solar wall taking into account the low economic cost.
For the Arquata District of Turin, measures included investment on demand side (thermal insulation); supply side (tri-generation plant and photovoltaic (PV) system); monitoring with Common Energy Management System (CEMS). Thermal insulations mainly consisted in the replacement of existing windows with low emission glazing, insulation of roofs and correction of thermal bridges.
With regard to the supply side, a tri-generation plant of 1 MW of power has been installed to supply a district heating network and to produce the cooling for ATC office building using an absorption chiller. The electricity produced is entirely sent to the grid.
Furthermore, PV modules have been installed on 12 residential buildings (120 kWp) and on ATC headquarter (50 kWp) with the aim to obtain a shading effect on S-W facade.