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News blog8 May 20232 min read

Family house with solar panels in Rijeka

 Family house with solar panels in Rijeka

Mr. Mladen Pujić welcomed us in his family apartment located in a small residential building in the city of Rijeka, Primorsko-goranska county. The heating and preparation of domestic hot water is provided by vacuum solar panels located on the rooftop of the building. The building has two floors and it accommodates three families. His apartment is located on the second floor including the attic of the building and it has 4 tenants at the moment. Ten years ago they had an only a smaller apartment on the second floor and they used wood for heating. It didn’t provide enough comfort since the heating system wasn’t indented and they had only wood stove in their living room. It was also very difficult to bring wood on the second floor in the building with no elevator.

When they bought an attic, they decided to make a complete reconstruction of the existing floor construction in order to accommodate underfloor and wall heating in their apartment. They also did a major upgrade on the roof (30 cm) and internal isolation (5 cm), and the outer building shell remained the same. The renovation, including the underfloor heating installation, lasted for two years. Even though it was a long process since included a lot of renovation and upgrades to the existing system, the owner did not experience any problems during the process.

The investment was around 4700 EUR, but it was co-funded through the tender “Green Energy in My Home”, financed by REA Kvarner and published in 2011. The subject of the tender was the installation of solar systems for heating and preparation of domestic hot water, as well as systems for heating and preparation of domestic hot water using biomass in households in Primorsko-goranska county. The owner received 1 600 EUR as support for the RHC development.

They opted for Viessman technology and they are very satisfied with the efficiency, they receive same energy as they did before the installation of the new system, but they doubled the space they live in and where the heating system is provided, and the comfort of living is incomparable. Solar vacuum collectors are located on the rooftop and 750 l hot water boiler in separate storage in the attic of the house.

Main drivers of this long, but successful process was an energy efficiency, energy-saving, innovation and comfort of living. Owner a lot of time reading and researching the new technologies and he is beyond satisfied with his decision.

New heating system in use Solar collectors
Previous replaced heating system Wood
Building type Residential building
Useful energy demand (kWh/m2a) – Before and after building shell
170 kWh/m2a – 80 kWh/m2a
Installed capacity (kWth) – Before and after 6m3 of wood – 5 m2 collectors and 750 l boiler
Input energy – Before and after 6 m3 of wood + electricity – 100% of solar
Initial investment (purchase and installation) 4700 EUR
Yearly savings on the energy bill (compared to previous system) 50% in EUR
Yearly energy savings (compared to previous system) 47% in MWh
Yearly CO2 emission reductions (only heating system replacement) 4,1 t CO2

This best practice is issued from the activities of Work Package 4 “Preparation of instruments for replacement campaigns” of the REPLACE project. Read it now to discover many more best practices illustrating the benefits of innovative low-carbon and renewable heating and cooling systems.


Publication date
8 May 2023