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District energy-efficient retrofitting

Energy Efficiency in Buildings

Retrofitting of the building envelope 

The Soma demonstration site district included 82 buildings, with 79 residential buildings, 2 guest houses and 1 convention centre. The district counts with different typologies of construction including one, two and three storey buildings and duplex. The buildings were built in 1982 and present medium constructive quality in a progressive ageing. The buildingsdid not have any insulation layer on the wall, with very poor insulation on the roof, which resulted in significant thermal losses. 

The renovation strategy for Soma demonstration site consisted of the application of passive measures such as the retrofitting of the building envelope in order to integrate insulation in the walls, roofs and windows. In addition, the replacement of the windows was plannedfor the convention centre: PVC framed double glazed windows with U-value of 1.2 W/m2K would have replaced the previous ones.

The retrofitting actions in Soma demonstration site were not finalized as initially planned; only a 20% of the buildings have been thermally insulated: 15 residential buildings, 1 guest house and 1 single lodging.

Building services (HVAC and lighting)

As part of the energy retrofitting project, the replacement of the lighting system was planned in order to reduce the electricity consumption and bill. A new LED lighting system should have been installed in the buildings. The electric systems and radiators have been retrofitted in 200 dwellings.


Energy Systems

In the demonstration site area, the buildings are heated by a central heating system. A local heating boiler is directly connected to the radiator systems inside the buildings. Lignite from Soma is used as a fuel in the local central boiler. Domestic Hot Water (DHW) is also supplied to the buildings from the central boiler.

In order to reduce energy consumption and increase the share of renewable energy sources, the integration of active measures was proposed.

District heating

The buildings in demonstration site are heated by a central heating system. In the new heating system initially planned, the heating demand of the buildings would have been supplied thanks to the surplus heat of Soma Thermal Power Plant, instead of using the existing central heating system. The intervention consisted in the construction of a new transmission line to supply heat energy from the main pump station to the demonstration site. In addition, a new local pump station, together with a newdistribution system and other district heating components (pump stations, control systems, building substations, etc.)would have been installed in the demonstration site.

These interventions were the original retrofitting project for Soma demonstration site. Although most of the transmission line has been constructed, after the final decision of the demonstration site owner, the distribution line investment was cancelled.

Solar thermal

The installation of solar collectors set the goal to reduce the energy consumption for the production of DHW supplied by the district heating. Solar collectors have been installed in all the buildings. The system includes 390 solar thermal collectors installed on the roof and faced to the South with a tilt angle to optimize solar energy gain

Building Integrated Photovoltaics (BIPV).

PV integration on rooftops of the buildings was considered for the Soma district in order to reduce the electricity consumption. Unfortunately, the intervention was not implemented.



Management system

The management system provides data in order to maintain the best inside comfort conditions, to assess the reduction of the energy consumption and to increase the energy efficiency and the ratio of renewable energy.

DEMS (District Energy Management System)

The system originally planned should have monitored the whole district heating, i.e. the pump stations, building/district level electricity measurements, weather conditions and PV system measurements. Due to the amendment of the actions, it has been only possible to implement measures for the building/district level electricity and the weather conditions.

BEMS (Building Energy Management System)

The Building Energy Management System was initially planned to include all the buildings of the district; however, due to the amendment, it has been only possible to monitor the buildings that were retrofitted. Indoor comfort quality parameters of each housing unit are monitored including indoor/outdoor temperature, humidity, light intensity, air flow and CO2sensors.

HEMS (Home Energy Management System) 

The system has been installed in the pilot dwellings in order to measure and assess the energy consumption and indoor comfort quality.

Monitoring platform and visualisation tools

The retrofitted dwellings and conditioned area are monitored to evaluate the energy performance and assess the environmental, social, economic and related ICT-measures impact. The implementation of monitoring platform and visualisation tools not only allow to collect data and store the information but also are creating awareness and verifying how people change their habits.