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Country & City

  • Croatia
  • Hvar


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The island of Hvar is located approximately 40 km off the Dalmatian coast in Croatia, and is the fourth largest Croatian island with a total area of 297 km². The SOLUTION demonstration area comprises the whole island.

The objective of Hvar was to make the energy supply 20 % self-sufficient by 2020 with improvements to the energy efficiency of existing buildings, as well as constructing new energy-efficient buildings as a primary measure. Altogether, 10 buildings were refurbished during the SOLUTION project – 5 private buildings and 5 public buildings (3 schools and 2 kindergartens), and 4 buildings were newly constructed.

In view of the abundant solar resources and the mild climate on the island, the demonstration site integrated solar thermal collectors and small and large-scale photovoltaic installations, as well as solar cooling. In addition, since there is a great deal of agricultural and kitchen waste on the island, biogas production was chosen as a solution to the problems linked with landfills and future waste management.

*The KPIs for the new building are compared with the baseline of a reference building.

The demonstration site Hvar in Croatia consists of an overall gross floor area of 8506 m², which has been refurbished, and 3168 m² that has been newly constructed.

As a result of energy efficiency, the total energy consumption of the renovated buildings was reduced from an average of 110 kWh/m²/yr (business as ususal) to 35 kWh/m²/yr representing a decrease of more than 65 % in comparison to the reference building. The reference building’s consumption exceeds 60 kWh/m²/yr year, while the total energy demand of the new buildings in Hvar is 38 kWh/m²/yr.

This means there are 638 MWh/yr of final energy savings for the renovation and 70 MWh/yr of final energy savings for the new buildings when compared to the reference values. According to the primary energy and CO2 factors provided by the project, the primary energy savings go up to 850 MWh/yr for the renovation and 126 MWh/yr for the new construction, while the CO2 reduction amounts to 289 tonnes per year for the renovation and 41 tonnes for the new construction every year.


Encountered barriers

Limited experience in the field of energy efficiency and large-scale photovoltaic operation.

National and international initiatives to train local architects, installation companies and construction companies on energy-efficient building development were launched. The topics included how to become a passive house planner, details and rules in passive house construction, etc.





Changes to photovoltaic feed-in tariffs in Croatia have a negative impact on the feasibility of larger-scale photovoltaic plants.


The testing phase of the biogas plant and the developments related to that caused delays in the (economically feasible) operation.


There are high investment costs when refurbishing the envelopes of buildings, and on an island these are even greater due to high transportation costs.


The implemented measures in Hvar feature:

Energy efficiency in buildings

  • Retrofitting the building envelope
    • Specific refurbishment measures had to be applied to the buildings on Hvar Island according to their period of construction and their characteristic construction materials (historic buildings from the 19th century to the 1950s, buildings from the 1950s to the 1980s, buildings from the 1980s to 2000)
  • Building integrated renewable energy sources
    • Photovoltaics

Energy systems integration

  • Waste-to-energy
    • Biogas from olive oil waste. Since there is a lot of agricultural and kitchen waste on the island, biogas production was chosen as a solution to the problems linked with landfills and future waste management. The waste is processed by extracting energy; high-quality compost is also obtained.
  • Thermal collectors

The best example from Hvar is the complete refurbishment of the school in Svirče, where the building was improved by thermal insulation to the external walls and the roof along with replacing the windows and doors. The boiler room was reconstructed and the fuel was switched to wood pellets. A heat pump, solar thermal system, 23 kW photovoltaic system and energy monitoring system were installed.

According to the design data, the yearly cost savings for energy result in EUR 52 475. Based on the poor financial data and lack of investment costs in the project documents, the payback calculation is not possible.

The CONCERTO approach: 

The overall objective of Hvar Island is to demonstrate the energetic self-sufficiency up to a quota of 20% until 2020.


One of the main topics of the project is the improvement of energy efficiency in buildings. The refurbishment and optimization of energy consumption present the biggest opportunities for savings and therefore will be applied on buildings in private and public sector. Assuming that energy consumption on the island will grow, primarily electricity consumption, it is necessary to exploit the (renewable) energy sources available on the island. This will be achieved by the implementation of renewable energy sources such as photovoltaic modules and solar thermal modules. In order to increase security of supply on the island, the implementation of Compressed Air Energy Storage units is planned. Such systems will be used in combination with photovoltaic installations.

Furthermore, the generation of energy from biomass is planned on the island (biomass incineration or biogas production). These plants fulfil the role of a demonstration project which can be applied on other islands/communities.

Additional information on CONCERTO in Hvar:

Low energy efficiency on island of Hvar causes high energy consumption which can significantly be reduced to achieve island self-sufficiency. Resources available on the island (solar energy, biomass) must be used to lower the total island energy consumption. A report on improved energy efficiency in buildings in Croatia can be found here.

Consultations with potential stakeholders show that there is a broad interest and need for the development of EE market via ESCO projects, but also a number of barriers, the most significant ones being the lack of financing and insufficient knowledge of the nature of such projects here.

Site facts and figures: 
  • Estimated population involved: 11,000
  • Approx. geographical area coverage: 297 km²
  • Approx. energy saving (in %): Information will follow
  • Approx. energy from RES: 20%


A biogas plant using residuals from olive-oil production is supposed to be built on the island. Unfortunately the implementation of the plant is postponed due to the political situation in Croatia right now.

The installation of photovoltaics with a total peak power of 780 kW is planned: 250 kW (4 plants) in the private sector, a 1 MW plant in the public sector and 30 kW as roof-integrated systems. Innovative hydrogen storage systems (in total 100 kW)  connected to PV are to be installed to show their feasability. A first system has been implemented at a school. If it shows success, then a larger storage is to be installed with the large 1 MW PV plant.

During the project 45 buildings (10,000 m² of public buildings and 8,000 m² of private buildings) will be refurbished, among them two large school buildings (Picture 1+2). The measures will include thermal insulation, replacement of old heating and cooling systems and, replacement of windows and doors.

Biogas plant

One large project within the CONCERTO activities at Hvar is the implementation of a new biogas plant. Actually it is a polygeneration plant, as it produces three outputs: electricity, heat and compost. The plant is a mobile type and consists of different containers (Picture 3) for all phases of the fermenting process.

As input biogenic materials like residues from olive oil production, vine-growing residues and other organic waste will be used (Picture 4). The electricity output of the cogeneration unit will be 80 kW , its thermal output will be 100 kW .